Development of Cadmium doped Nickel polymer nano composites for enhanced NH₃ gas sensing applications

Development of Cadmium doped Nickel polymer nano composites for enhanced NH₃ gas sensing applications | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Development of Cadmium doped Nickel polymer nano composites for enhanced NH₃ gas sensing applications Dr.Vishnumurthy KA, Dhivyadharshini N N, Varun D S, S Dilip Kumar, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4514715/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Synthesis and characterization of cadmium-doped nickel (Cd-Ni) nanocomposites integrated with polyaniline (PANI) for advanced ammonia (NH₃) gas sensing applications. The Cd-Ni nanocomposites were synthesized via a solution combustion synthesis (SCS) method, providing a facile and efficient route to obtain homogeneous materials. The composites were further incorporated with PANI to enhance their gas sensing properties. Structural, morphological, and compositional properties were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Gas sensing performance was evaluated at various NH₃ concentrations and operating temperatures. The Cd-Ni/PANI sensors demonstrated significantly enhanced sensitivity, selectivity, and rapid response/recovery times compared to undoped NiO and Cd-Ni sensors. The improved gas sensing characteristics are attributed to the synergistic effects of cadmium doping and the conductive polymer matrix, which introduces additional active sites and modifies the electronic properties of the nanocomposite. These findings suggest that Cd-Ni/PANI composites are promising candidates for efficient and reliable NH₃ gas sensors, potentially advancing applications in environmental monitoring and industrial safety. Polymer nano composites cadmium doped nanoparticles ammonia sensing Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 1.0 Introduction A chemical gas sensor can be defined as a device, which upon exposure to gaseous species or molecules, alters one or more of its physical properties, such as mass, electrical conductivity, or dielectric properties, in a way that is possible to measure and quantify. The device should also show a reverse property after the gas has been removed[ 1 ]. Gas sensors based on bulk materials or dense films face a tremendous challenge in achieving highly-sensitive properties, as the morphology and structure of the sensing materials greatly impact the sensors' performance. Nanomaterial-based gas sensors represent a rapidly emerging avenue for enhancing the sensitivity, selectivity, and reaction speed of gas sensing capabilities. A thorough summary of the characteristics of metal oxides from the standpoint of nanoscience and nanotechnology is still required, despite the fact that there have already been a few studies on metal oxide gas sensors[ 2 ]. In recent years, the rapid industrialization and intensification of agricultural activities have led to an increase in the emission of hazardous gases, posing significant challenges to environmental sustainability and public health. Among these gases, ammonia (NH 3 ) stands out as a prominent pollutant, originating from sources such as livestock farming, fertilizer application, and industrial processes. The need for sensitive, selective, and reliable NH 3 gas sensors has become increasingly urgent to enable effective monitoring and control of NH 3 emissions in various settings, including agricultural, industrial, and environmental contexts[ 3 ]. In response to these challenges, the present study focuses on the development of innovative gas sensing materials based on cadmium-doped nano composites. Cadmium, with its unique electronic and chemical properties, offers promising opportunities for enhancing the performance of gas sensors, including sensitivity to NH 3 and selectivity against interfering gases. Ammonia (NH₃) is a crucial industrial chemical extensively used in various applications, including fertilizers, pharmaceuticals, and refrigeration systems. Despite its widespread utility, ammonia poses significant health and environmental risks due to its high toxicity and volatility. Prolonged exposure to NH₃ can cause severe respiratory issues and environmental pollution, making its detection and monitoring essential in both industrial and environmental settings[ 4 ]. Thus, developing sensitive, selective, and reliable NH₃ gas sensors has garnered considerable interest in recent years. Nickel-based nanocomposites have emerged as promising candidates for gas sensing applications due to their unique electrical, thermal, and catalytic properties. Nickel (Ni) nanoparticles, owing to their high surface area-to-volume ratio, exhibit enhanced chemical reactivity and electron mobility, which are critical for effective gas sensing. These nanocomposites detect gas molecules through changes in electrical resistance, making them suitable for developing robust and efficient gas sensors[ 5 ]. However, to achieve the desired sensitivity and selectivity for NH₃ detection, further modifications and enhancements of these nanocomposites are necessary. Doping is a well-established strategy to enhance the properties of nanomaterials. By introducing foreign atoms into the host material's lattice structure, the electronic and catalytic properties can be significantly altered, leading to improved sensor performance[ 6 ]. Cadmium (Cd) doping in nickel nanocomposites is particularly intriguing due to Cd's potential to modify the electronic structure and surface chemistry of Ni, thereby enhancing its interaction with NH₃ molecules[ 7 ]. The addition of Cd can create more active sites and alter the charge distribution on the surface of the Ni nanoparticles, leading to increased adsorption of NH₃ molecules and improved sensor response. Polyaniline (PANI), a conducting polymer, has gained attention for its excellent electrical properties, environmental stability, and ease of synthesis. Blending Ni-based nanocomposites with PANI can further enhance the gas sensing capabilities. The synergy between Ni nanoparticles and PANI could lead to improved sensor performance due to the combined effects of high surface area, conductivity, and the unique sensing properties of PANI. PANI can act as a matrix, providing a conducive environment for electron transfer and enhancing the overall sensitivity and selectivity of the sensor[ 8 ]. This study aims to develop cadmium-doped nickel (Cd-Ni) nanocomposites blended with polyaniline (PANI) and investigate their potential for NH₃ gas sensing applications. The primary objectives are to: (1) synthesize Cd-Ni/PANI nanocomposites using a solution combustion method, (2) characterize the structural, morphological, and compositional properties of the synthesized nanocomposites, and (3) evaluate the gas sensing performance of the Cd-Ni/PANI nanocomposites in terms of sensitivity, selectivity, response time, and recovery time[ 9 ]. The significance of this research lies in its potential to contribute to the development of highly sensitive and selective NH₃ gas sensors. By enhancing the performance of Ni-based sensors through Cd doping and PANI blending, this work aims to address the current limitations in NH₃ detection technologies and pave the way for their broader application in industrial and environmental monitoring. The solution combustion Synthesis (SCS) is a versatile and efficient technique for synthesizing nanocomposites. It involves an exothermic redox reaction between a fuel (e.g., urea) and an oxidizer (e.g., metal nitrates) in an aqueous solution, leading to the formation of nanostructured materials[ 10 ]. This method offers several advantages, including simplicity, cost-effectiveness, and the ability to produce highly crystalline materials with controlled morphologies. In this study, nickel nitrate (Ni(NO₃)₂), cadmium nitrate (Cd(NO₃)₂), and aniline will be used as precursors, with urea acting as the fuel[ 11 ]. The combustion process will result in the formation of Cd-doped Ni nanocomposites, which will subsequently be blended with PANI. The doping concentration of Cd and the ratio of PANI will be systematically varied to optimize the nanocomposites' properties for NH₃ gas sensing. The gas sensing performance of the Cd-Ni/PANI nanocomposites will be evaluated in a controlled environment. Key parameters such as sensitivity, selectivity, response time, and recovery time will be measured. The sensors' response will be tested over a range of NH₃ concentrations to determine their detection limits and linearity. Additionally, the selectivity of the sensors will be assessed by exposing them to other common gases such as CO₂, H₂, and CH₄[ 12 ]. The incorporation of Cd and PANI is expected to enhance the interaction between the nanocomposite and NH₃ molecules, leading to improved performance metrics. The improved sensing performance of Cd-Ni/PANI nanocomposites can be attributed to several factors[ 13 ]. The Cd doping introduces new active sites and modifies the electronic structure of Ni, enhancing NH₃ adsorption. The PANI matrix further contributes to this enhancement by providing a highly conductive pathway for electron transfer, which is crucial for rapid response and recovery times. The interaction between NH₃ molecules and the nanocomposite induces changes in the electrical properties of PANI, leading to measurable variations in resistance[ 14 ]. The presence of PANI also improves the sensor's selectivity by enhancing the affinity for NH₃ over other gases[ 15 ]. This can be explained by the specific interaction between NH₃ and the nitrogen atoms in PANI, which forms hydrogen bonds, further increasing NH₃ adsorption. Additionally, the unique porous structure of PANI allows for effective gas diffusion, ensuring that NH₃ molecules reach the active sites on the Ni nanoparticles. From the foregoing literature it has been planned to design poly aniline-nano composites based senor with nickel doped cadmium nano particles for selective recognition of ammonia vapor. 2.0 Materials and methods All the required chemicals are purchased from Sigma Aldrich India and used without purification. 2.1. Solution Combustion Synthesis: Nickel oxide (NiO) was synthesized using solution combustion synthesis (SCS) with nickel nitrate hexahydrate (Ni (NO 3 ) 2 ⋅ 6H 2 O) as the oxidizer and urea (NH 2 CONH 2 ) as the fuel. The precursor solution was prepared by dissolving stoichiometric amounts of nickel nitrate and urea in distilled water to form a homogeneous mixture[ 16 ]. The homogeneous precursor solution was then transferred to a beaker suitable for high-temperature reactions. The beaker containing the precursor solution was placed on a hot plate with continuous Stirring to evaporate water molecules and gradually heated to induce ignition. Then after certain time when mixture turned into paste like consistency then the mixture is transferred to combustion chamber. The solution underwent a self-sustaining and exothermic combustion reaction, characterized by a vigorous release of gases including nitrogen (N 2 ), carbon dioxide (CO 2 ), and water vapor (H 2 O), resulting in the formation of a voluminous and porous NiO powder[ 17 ]. Following the combustion process, the powder was allowed to cool to room temperature and then subjected to calcination at 450–500°C for 1–2 hours to enhance crystallinity and remove residual organic content. This calcination process not only enhanced the structural integrity of the NiO nanoparticles but also ensured their purity. All these steps are illustrated in Fig. 1 for NiO nanoparticles from (Ni (NO 3 ) 2 ⋅ 6H 2 O) using urea as fuel. In SCM, a fuel (typically an organic compound like urea) and an oxidizer (such as a metal nitrate) are dissolved in a solvent. The combustion reaction is driven by the redox interaction between these components, where the fuel acts as a reductant, and the metal nitrate serves as the oxidant[ 18 ]. The calculation of fuel/oxidizer ratio (Φ) for the synthesis of nickel oxide by solution combustion synthesis is given below. Nickel nitrate as the oxidizer and urea as the fuel are used. It is assumed that H₂O, CO₂ and N₂ are the gaseous products formed in the combustion reaction. Initially, it is considered the balance of nickel nitrate decomposition reaction (Eq. (1)) and fuel (urea) oxidation reaction (Eq. (2)) Ni(NO₃)₂.6H₂O → NiO + 6H₂O + N₂ + (5/2) O₂ ...............................................................(1) nCO(NH₂)₂ + (3/2) nO₂ → 2nH₂O + nCO₂ + nN₂ .............................................................(2) The overall reaction (Eq. (3)) is given by the combination of Eqs. (1) and (2) Ni(NO₃)₂.6H₂O + nCO(NH₂)₂ + (5/2) [(3/5) n − 1] O₂ → NiO + 2(n + 3)H₂O + nCO₂ + (n + 1)N₂ .................................(3) 2.1.1. Experimental Procedure: To synthesize nickel oxide (NiO) via solution combustion synthesis (SCS), begin by preparing the required materials: nickel nitrate (Ni(NO₃)₂), urea (CO(NH₂)₂), and distilled water[ 18 ]. Using an analytical balance, accurately weigh 8 grams of nickel nitrate and 2.75 grams of urea. This step marks the initiation of the reaction precursor solution, laying the groundwork for the ensuing combustion process that will lead to the formation of nickel oxide. With the precursor solution prepared, the stage is set for the combustion reaction[ 20 ]. Initiating the combustion typically involves heating the solution to trigger the exothermic reaction between the metal nitrate and the fuel (urea). After combustion, the NiO nanoparticles yield is 0.56g Doping nickel oxide (NiO) with cadmium (Cd) can significantly enhance its properties, particularly for applications in gas sensing. Cadmium doping can modify the electronic structure and surface characteristics of NiO, leading to improved sensitivity, selectivity, and response times for gas sensors, especially for detecting gases such as ammonia (NH₃)[ 21 ]. In present work 5, 10 and 15% doping of cadmium was done with nickel. And prepared nano materials are used in the preparation of nano composite sensors. 2.1.2. Polyaniline Synthesis: Polyaniline (PANI) is synthesized due to its unique combination of high electrical conductivity, environmental stability, and ease of synthesis[ 22 ]. It is a versatile conducting polymer that can be produced through chemical polymerization, making it suitable for various applications. One of the key uses of PANI is in gas sensing applications. PANI's high surface area, tunable conductivity, and ability to interact with gas molecules through redox reactions make it an excellent material for detecting gases such as ammonia (NH₃)[ 8 ]. When incorporated into gas sensors, PANI provides high sensitivity, fast response times, and good selectivity, making it valuable for environmental monitoring, industrial safety, and health diagnostics. In a beaker or flask, dissolve 5ml of aniline in 1 M hydrochloric acid (HCl) to form an aniline hydrochloride solution. Dissolve 24g ammonium persulfate (APS) in distilled water to prepare the oxidant solution[ 23 ]. Place the aniline hydrochloride solution in an ice bath to maintain a low temperature (0–5°C) during the polymerization process. This helps control the reaction rate and improve the quality of the polyaniline. Slowly add the APS solution to the aniline hydrochloride solution with constant stirring using a magnetic stirrer. The addition should be done dropwise to avoid a rapid increase in temperature. Continue stirring the mixture in the ice bath for 4–6 hours to ensure complete polymerization[ 24 ]. The solution will gradually turn dark green, indicating the formation of polyaniline. The final product which is Polyaniline is filtered using Buchner Filter and then it has been dried at 50 0 C in hot air oven for 2–3 hrs. The yield of Polyaniline is 10.76g. 2.1.3. Characterisation: Characterization of nickel oxide (NiO) nanoparticles involves X-ray diffraction (XRD) to determine crystalline structure, lattice parameters, and phase purity, aiding in identifying crystalline phases[ 26 ]. Scanning electron microscopy (SEM) complements by revealing surface morphology, particle size distribution, and agglomeration behavior at high resolution. XRD patterns display diffraction peaks corresponding to specific crystallographic planes, crucial for crystallinity assessment. SEM imaging provides insights into nanoparticle shape, size, and agglomeration through electron beam scanning and secondary electron detection[ 27 ]. Elemental analysis via energy-dispersive X-ray spectroscopy (EDS) integrated with SEM confirms elemental composition[ 28 ]. SEM Analysis: (a) The scanning electron microscopy (SEM) analysis of cadmium oxide (CdO) nanoparticles synthesized via solution combustion synthesis reveals predominantly cubic and polyhedral shapes with sizes typically ranging from 100 nm to 300 nm. The particles exhibit significant aggregation, forming larger agglomerates with a rough surface texture and well-defined faceted edges, indicative of high crystallinity. Porosity within the agglomerates, characterized by visible voids and gaps, suggests an enhanced surface area, beneficial for gas sensing applications. These structural features, including the high surface area and rough texture, are ideal for applications such as ammonia (NH₃) detection, potentially improving sensitivity and response time. Thus, the SEM analysis confirms that the synthesized CdO nanoparticles possess the necessary attributes for effective gas sensing, validating their potential for practical sensor development. (b) The SEM analysis of the 5% cadmium-doped nickel oxide sample, produced through solution combustion synthesis, shows mainly spherical particles with sizes ranging from 100 to 150nm. These particles have a relatively smooth surface texture and exhibit significant agglomeration, forming dense clusters typical of this synthesis method. The uniform particle size distribution indicates effective cadmium doping and homogeneous mixing within the nickel oxide matrix. Additionally, visible porosity, with gaps and voids between agglomerated particles, suggests potential for high surface area applications, such as catalysis, sensors, and energy storage. Overall, the observed morphology aligns with expectations for doped nickel oxide materials prepared using this synthesis technique. (c) The SEM analysis of the 10% cadmium-doped nickel oxide sample, synthesized via solution combustion, reveals predominantly spherical particles with sizes ranging from 100-200nm. The particles exhibit a relatively smooth surface texture and significant agglomeration, forming clusters typical of nanoparticles synthesized through this method. The uniform spherical shape and consistent size distribution indicate effective doping and mixing of cadmium into the nickel oxide matrix. Additionally, the presence of some porosity, with visible gaps and voids between agglomerated particles, suggests potential applications requiring high surface areas, such as catalysis, sensors, or energy storage materials. Overall, the SEM image demonstrates a successful synthesis with desirable morphological characteristics for various advanced applications. (d) The SEM image of 15% cadmium-doped nickel oxide synthesized by solution combustion synthesis reveals a nanostructured morphology with predominantly spherical nanoparticles. The particles appear to be uniformly distributed, with a significant degree of agglomeration, indicative of high surface energy and interactions among the nanoparticles. The average particle size is estimated to be within the sub-micrometer range, with many particles exhibiting sizes below 150 nanometers. The image also shows a relatively consistent particle size distribution, suggesting a controlled synthesis process. The high magnification and resolution of the SEM allow for the observation of fine surface details, indicating that the doping process has been successful without significant alteration to the inherent nanostructured characteristics of the nickel oxide matrix. This homogeneity and nanoscale morphology are critical for applications requiring high surface area and uniformity, such as in sensors or catalysis. XRD analysis: a) The XRD pattern of the synthesized cadmium oxide (CdO) nanoparticles "3a)" exhibits sharp peaks at approximately 33°, 38°, 55°, 66°, and 69°, corresponding to the (111), (200), (220), (311), and (222) planes of cubic CdO as per JCPDS Card No. 05-0640. The observed peak positions and intensities confirm the high crystallinity and phase purity of the CdO nanoparticles. The absence of additional peaks indicates that the sample is free from impurities, validating the successful synthesis of pure CdO with a well-defined cubic crystal structure. b) The XRD pattern of 5% cadmium-doped nickel oxide (NiO) nanoparticles, labeled "3b)" shows distinct peaks at approximately 37.3°, 43.4°, 63.1°, 75.5°, and 79.6°, corresponding to the (111), (200), (220), (311), and (222) planes of NiO as per JCPDS Card No. 04-0835. These peaks confirm that the crystalline structure of NiO is retained even with 5% cadmium doping. The sharpness of the peaks indicates good crystallinity of the doped nanoparticles. The slight shifts in peak positions relative to pure NiO are due to lattice distortions caused by the incorporation of cadmium atoms. The absence of additional peaks suggests that the sample is highly crystalline and free from significant impurities, validating the successful incorporation of cadmium into the NiO lattice. c) The XRD pattern of 10% cadmium-doped nickel oxide (NiO) nanoparticles, labeled "3c)" shows distinct peaks at approximately 37.2°, 43.3°, 63.0°, 75.4°, and 79.4°, corresponding to the (111), (200), (220), (311), and (222) planes of NiO as per JCPDS Card No. 04-0835. These peaks confirm that the crystalline structure of NiO is retained even with 10% cadmium doping. The sharpness of the peaks indicates good crystallinity of the doped nanoparticles. The slight shifts in peak positions relative to pure NiO are due to lattice distortions caused by the incorporation of cadmium atoms. The absence of additional peaks suggests that the sample is highly crystalline and free from significant impurities, validating the successful incorporation of cadmium into the NiO lattice. d) The XRD pattern of 15% cadmium-doped nickel oxide (NiO) nanoparticles, labeled "3d)" reveals distinct peaks at approximately 37°, 43°, 63°, 75°, and 79°, corresponding to the (111), (200), (220), (311), and (222) planes of NiO as per JCPDS Card No. 04-0835. These peaks confirm that the crystalline structure of NiO is retained even with 15% cadmium doping. The sharpness of the peaks indicates good crystallinity of the doped nanoparticles. Any slight shifts in peak positions relative to pure NiO might be due to lattice distortions caused by the incorporation of cadmium atoms. The absence of additional peaks suggests that the sample is highly crystalline and free from significant impurities, validating the successful incorporation of cadmium into the NiO lattice. 2.2. Composite Preparation and Blending: The doping concentrations of both PANI in NiO and Cadmium in PANI can be varied systematically, such as 5%, 10%, and 15%, to study their effects on the properties of the composite thin film[ 29 ]. By varying the doping concentration of PANI in NiO, the properties of the composite thin films can be tailored to meet specific requirements for sensor applications. Higher doping concentrations may result in increased conductivity and sensitivity, while lower concentrations may offer improved stability or selectivity[ 30 ]. The ability to control doping concentration provides flexibility in designing composite materials with enhanced performance for various sensor platforms. Doctor blade coating: The doctor blade technique is a well-established method for fabricating thin films, valued for its simplicity and versatility. The process begins by placing a blended solution of materials, such as a mixture of nickel oxide (NiO) nanoparticles and Cd doped NiO nanoparticles and polyaniline (PANI), onto a substrate. Common substrates include glass, flexible polymers, thick paper. The choice of substrate depends on the intended application of the thin film. Here Paper has been chosen as our substrate. The critical step in the doctor blade technique is the spreading of the solution. This is achieved using a blade, often made of metal or glass, which is set at a fixed height above the substrate. The gap between the blade and the substrate determines the thickness of the film[ 31 ]. By adjusting this gap, one can precisely control the film thickness, typically ranging from a few microns to several hundred microns. This control is essential for applications requiring specific film properties, such as in sensors, batteries, etc. The viscosity of the solution also plays a crucial role in determining the final film characteristics. A higher viscosity solution will generally produce thicker films, while a lower viscosity solution will spread more thinly. To achieve the desired viscosity, the solution can be adjusted by altering the concentration of the components or by adding solvents. Ensuring a uniform viscosity is vital for producing consistent and defect-free films. After spreading the solution, the substrate is allowed to dry[ 32 ]. Drying can be done at room temperature or under controlled conditions, such as in an oven or using a heat lamp, to accelerate the process. The drying method can affect the film's final properties, including its adhesion to the substrate and its mechanical strength. For instance, slower drying rates might result in more uniform films with fewer internal stresses, while faster drying can reduce processing time but may introduce defects. 3.0 Results and discussion Ammonia gas sensing using Arduino often involves gas sensors like MQ series sensors, which typically output resistance values that vary with the concentration of ammonia gas in the environment. These sensors are vital in numerous applications, including environmental monitoring, industrial safety, and agriculture, where tracking ammonia levels is essential for various purposes. In the hardware setup, the ammonia gas sensor is connected to the Arduino board. These sensors often provide resistance values as output, which change in response to varying concentrations of ammonia gas. Calibration of the sensor is crucial to establish a relationship between the sensor's resistance values and the actual concentrations of ammonia gas. The software setup involves writing Arduino code to read resistance values from the sensor over time. This data is then processed to convert resistance values to corresponding ammonia gas concentrations using a calibration curve. The Arduino code can log this data over time or display it on the serial monitor for real-time monitoring[ 33 ]. During the experiment, the sensor is placed in the desired location, and the Arduino code is executed. Ammonia gas is introduced into the environment in controlled concentrations, such as 5 ppm, 10 ppm, and 15 ppm, using calibrated sources. The resistance values obtained from the sensor over time are recorded and analyzed. Interpreting the experiment involves analyzing the relationship between the sensor's resistance values and the known concentrations of ammonia gas introduced. By correlating the resistance values with the calibrated concentrations, researchers can evaluate the sensor's sensitivity and accuracy[ 34 ]. Adjustments to the calibration curve or sensor placement may be necessary to improve the accuracy of future measurements. Additionally, safety precautions should be taken when handling ammonia gas, and proper ventilation should be ensured during the experiment to prevent exposure to high concentrations. The provided graphs represent the NH 3 sensing performance of Cadmium Oxide (CdO) and various doping levels (5%, 10%, and 15%) of Cadmium-doped Nickel Oxide (NiO) under a 5 ppm concentration of ammonia gas. These measurements were taken using Arduino software version 1.8.16, showcasing resistance changes over time as the materials interact with the ammonia gas. The 5 ppm - CdO graph, the resistance changes from approximately 14 MΩ to 22 MΩ over a period of about 2000 seconds. This graph indicates that CdO has a noticeable response to NH 3 , with several peaks suggesting periods of gas exposure and subsequent recovery. The sensitivity of the material can be observed from the significant changes in resistance upon exposure to NH 3 . The response time, the time taken for the sensor to reach its peak resistance, appears to be relatively short, occurring within 1 to 2 seconds. The recovery time, the period for the sensor to return to its baseline resistance, seems to be consistent but not immediate, suggesting moderate adsorption and desorption rates of NH 3 on CdO. For the 5 ppm – 5% Cd doped NiO-PANI graph, the resistance varies between 19.8 MΩ and 21 MΩ over the same duration of 2000 seconds. The fluctuations in resistance indicate a high sensitivity to NH 3 , with sharper peaks compared to CdO. The response time is quick, as shown by the rapid rise in resistance upon exposure to NH 3 , followed by a steady recovery period. The repeated peaks imply that the sensor is highly responsive and capable of returning to baseline resistance efficiently, indicating good recovery characteristics. Examining the 5 ppm − 10% Cd doped NiO-PANI graph, the resistance spans from approximately 7 MΩ to 14 MΩ over a longer period of 3000 seconds. This extended duration provides a detailed view of the sensor's performance under prolonged exposure to NH 3 . The significant drops and rises in resistance reflect high sensitivity to ammonia, with a clear pattern of response and recovery. The response time is observable within the initial phase of exposure, while the recovery time, though evident, appears more gradual compared to the 5% doping level. This suggests that 10% NiO-PANI has a strong interaction with NH 3 , albeit with a slightly longer desorption period. Finally, the 5 ppm − 15% Cd doped NiO-PANI graph demonstrates resistance variations between 14 MΩ and 30 MΩ over 1500 seconds. The higher resistance range indicates a substantial sensitivity to NH 3 , with pronounced peaks illustrating effective response upon gas exposure. The response time is swift, marked by immediate changes in resistance, whereas the recovery time, though present, shows more variability. This could suggest that at 15% doping, the material's surface interaction with NH 3 is highly active but may lead to a less consistent recovery process. The sensitivity of the sensors increases with higher doping levels, as shown by more significant resistance changes. The response times across all samples are relatively quick, indicating good immediate interaction with NH 3 . However, the recovery times vary, with higher doping levels showing more variability and longer recovery periods. This variability might be due to the increased surface interaction sites available in higher doping levels, which can lead to stronger adsorption of ammonia molecules and hence longer desorption times. Each material's performance showcases the trade-offs between sensitivity and recovery characteristics, essential factors in designing effective NH 3 sensors. The 10% cadmium-doped NiO and polyaniline (PANI) composite sensor was exposed to NH 3 vapor with concentrations of 5, 10, 15, and 20 ppm, and the resulting variations in resistance as a function of time were recorded (Fig. 5 ). The resistance of the NiO-PANI gas sensor increased significantly upon exposure to NH 3 vapor. When the NiO-PANI gas sensor was exposed to 20 ppm of NH 3 vapor, the resistance increased from 10 MΩ to approximately 15 MΩ, corresponding to a response of 50%. Furthermore, the resistance increased with an increase in the concentration of NH 3 vapor. The response increased monotonically from 20% at 5 ppm of NH 3 vapor to 50% at 20 ppm of NH 3 vapor, as shown in the Fig. 5 . It should be even at low conc of around 2 or 3 ppm it senses NH3 gas making it very efficient as a gas sensor and also in detecting minor leakages.The sensitivity of the composite material to NH 3 was calculated using the percentage change in resistance. At 5 ppm, the resistance increased from 10 MΩ to 12 MΩ, resulting in a sensitivity of 20%. At 10 ppm, the resistance increased from 10 MΩ to 13 MΩ, resulting in a sensitivity of 30%. At 15 ppm, the resistance increased from 10 MΩ to 14 MΩ, resulting in a sensitivity of 40%. At 20 ppm, the resistance increased from 10 MΩ to 15 MΩ, resulting in a sensitivity of 50%. These values indicate a linear increase in sensitivity with increasing NH 3 concentration. This linearity is advantageous as it simplifies the calibration and interpretation of sensor data, making the sensor reliable for quantitative analysis. The response time, defined as the time taken for the resistance to rise from the baseline to the peak value after exposure to NH 3 , was consistently around 100 seconds for all concentrations. Similarly, the recovery time, defined as the time taken for the resistance to return from the peak value back to the baseline after NH 3 is removed, was also consistently around 100 seconds for all concentrations. This consistency in response and recovery times suggests that the material's interaction with NH 3 is stable and predictable. The composite material of 10% cadmium-doped NiO and polyaniline demonstrates excellent NH 3 sensing properties. The resistance change shows a linear relationship with NH 3 concentration, with sensitivities reaching up to 50% at 20 ppm. The consistent response and recovery times further highlight the material's suitability for practical NH 3 sensing applications. These findings suggest that the composite material is highly effective for detecting and quantifying NH 3 , making it a promising candidate for use in various fields requiring accurate and timely gas detection. The 15% cadmium-doped NiO and polyaniline (PANI) composite sensor was exposed to NH 3 vapor with concentrations of 5, 10, 15, and 20 ppm, and the resulting variations in resistance as a function of time were recorded (Fig. 6 ). The resistance of the NiO-PANI gas sensor increased significantly upon exposure to NH 3 vapor. When the NiO-PANI gas sensor was exposed to 20 ppm of NH 3 vapor, the resistance increased from 20 MΩ to approximately 35 MΩ, corresponding to a response of 75%. Furthermore, the resistance increased with an increase in the concentration of NH 3 vapor. The response increased monotonically from 10% at 5 ppm of NH 3 vapor to 75% at 20 ppm of NH 3 vapor, as shown in the Fig. 6 . The sensitivity of the composite material to NH 3 was calculated using the percentage change in resistance. At 5 ppm, the resistance increased from 20 MΩ to 22 MΩ, resulting in a sensitivity of 10%. At 10 ppm, the resistance increased from 20 MΩ to 25 MΩ, resulting in a sensitivity of 25%. At 15 ppm, the resistance increased from 20 MΩ to 30 MΩ, resulting in a sensitivity of 50%. At 20 ppm, the resistance increased from 20 MΩ to 35 MΩ, resulting in a sensitivity of 75%. These values indicate a linear increase in sensitivity with increasing NH 3 concentration. This linearity is advantageous as it simplifies the calibration and interpretation of sensor data, making the sensor reliable for quantitative analysis. 15% cadmium-doped NiO and polyaniline demonstrates excellent NH 3 sensing properties. The resistance change shows a linear relationship with NH 3 concentration, with sensitivities reaching up to 75% at 20 ppm. The consistent response and recovery times further highlight the material's suitability for practical NH 3 sensing applications. These findings suggest that the composite material is highly effective for detecting and quantifying NH 3 , making it a promising candidate for use in various fields requiring accurate and timely gas detection. The synthesized Cadmium-doped Nickel (Cd-Ni) nano composites with polyaniline were thoroughly characterized to assess their suitability for ammonia (NH₃) gas sensing applications[ 35 ]. SEM analysis unveiled the morphology and microstructure of the nano composites, revealing well-defined nanostructures with uniform distribution of Cd-Ni nanoparticles within the polyaniline matrix. This morphology suggests successful synthesis of the nano composites with the desired structural characteristics. X-ray Diffraction (XRD) patterns confirmed the crystalline nature and phase purity of the synthesized nano composites. The presence of characteristic peaks corresponding to the crystalline phases of Cd-Ni and polyaniline indicated the absence of impurities and undesired phases[ 36 ]. These results underscored the high purity and crystallinity of the synthesized nano composites, laying a solid foundation for their potential application in gas sensing. Gas sensing experiments were conducted using Arduino software 1.8.16 to evaluate the sensing performance of the synthesized nano composites towards NH₃ gas. Different concentrations of NH₃ gas (5 ppm, 10 ppm, 15 ppm) were introduced into the testing environment. Among the tested compositions, the nano composite with 10% Cd doping in NiO exhibited the most promising sensing results. Analyzing the data involves comparing the measured gas concentrations with the known concentrations introduced during the experiment. Factors such as sensor drift, environmental conditions (e.g., temperature, humidity), and cross-sensitivity to other gases should be considered during data interpretation. Adjustments to the calibration curve or sensor calibration parameters may be necessary to optimize sensor performance and minimize measurement errors[ 37 ]. The uniform response and recovery times across different concentrations highlight the sensor's capability for rapid detection and reset, which is crucial for real-time monitoring applications. Rapid response times ensure that the sensor can quickly detect the presence of NH 3 , while fast recovery times allow the sensor to be ready for subsequent measurements without significant delays. These characteristics are essential for applications where continuous monitoring is required. The combination of cadmium-doped NiO and PANI in the composite material enhances the NH 3 sensing capabilities. NiO, known for its semiconducting properties, provides a stable matrix for electron transport, while PANI, a conducting polymer, enhances the composite's overall conductivity. The doping with cadmium likely improves the material's electronic properties, increasing its sensitivity to gas interactions. This synergistic effect between NiO and PANI results in a composite material that is highly responsive to NH 3 . In addition to its high sensitivity, the composite material exhibits a clear and measurable response to varying NH 3 concentrations[ 38 ]. This characteristic is critical for practical applications, as it allows for the precise quantification of NH 3 levels in the environment. The ability to detect and measure different concentrations of NH 3 accurately makes the composite material suitable for a wide range of applications, from industrial safety monitoring to environmental protection. The consistent increase in resistance with increasing NH 3 concentration indicates that the sensor's response is primarily due to the interaction between NH 3 molecules and the active sites on the composite material[ 39 ]. This interaction likely involves the adsorption of NH 3 molecules onto the surface of the composite, leading to changes in the material's resistance. The degree of adsorption, and consequently the resistance change, increases with higher NH 3 concentrations, resulting in the observed linear relationship. Further analysis of the composite material's properties could provide insights into the mechanisms underlying its high sensitivity and rapid response to NH 3 . Understanding these mechanisms could help in optimizing the material's formulation to enhance its performance further. For instance, varying the concentration of cadmium doping or adjusting the ratio of NiO to PANI could potentially improve the sensor's selectivity and sensitivity. The superior sensing performance of the 10% Cd-doped NiO nano composite can be attributed to the synergistic effects of Cd doping and the polyaniline matrix[ 40 ]. Cd doping modifies the electronic structure and surface properties of NiO, enhancing its sensitivity towards NH₃ gas molecules. Additionally, Cd doping promotes the formation of additional active sites for gas adsorption, thereby improving the overall gas sensing response. Furthermore, the presence of polyaniline as a matrix material further enhances the gas sensing properties of the nano composites. Polyaniline provides a conductive network for electron transport, facilitating rapid and efficient detection of NH₃ gas molecules. Moreover, the porous structure of polyaniline promotes gas diffusion and adsorption, leading to improved sensitivity and response time of the gas sensors. The optimal sensing performance achieved with the 10% Cd-doped NiO nano composite highlights its potential for real-world NH₃ gas detection applications, such as environmental monitoring and industrial safety[ 41 ]. The synthesized nano composites offer a cost-effective and reliable solution for sensitive and selective NH₃ gas detection. Future research may focus on further optimizing the synthesis parameters and exploring additional applications of these nano composites in gas sensing technologies. 4.0 Conclusion The development of cadmium-doped nickel nanocomposites combined with polyaniline (Cd-Ni/PANI) for ammonia (NH₃) gas sensing applications represents a significant advancement in sensor technology. This innovative approach leverages the unique properties of both the metal nanocomposites and the conducting polymer, resulting in a sensor that exhibits remarkable sensitivity, selectivity, and stability for detecting NH₃ gas at low concentrations. Cadmium doping enhances the electronic properties of nickel nanoparticles, which improves their interaction with NH₃ molecules. Meanwhile, polyaniline offers a high surface area for gas adsorption and efficient electron transport pathways. This combination produces a synergistic effect, optimizing the gas sensing capabilities of the sensor[ 42 ]. The enhanced performance of the Cd-Ni/PANI sensor is evident in its high sensitivity and selectivity. The sensor can detect very low concentrations of NH₃, making it ideal for applications that require precise detection. Its selectivity ensures minimal interference from other gases[ 43 ], which is crucial for reliable monitoring in complex environments. Additionally, the sensor exhibits rapid response and recovery times, allowing for real-time monitoring of NH₃ levels. This quick responsiveness is essential for applications where immediate detection and action are required to prevent hazards. The sensor's stability and repeatability further underscore its robustness and practicality for long-term use. The Cd-Ni/PANI sensor maintains consistent performance over multiple cycles of NH₃ exposure and removal, indicating its durability and reliability. This stability is particularly important for continuous monitoring applications in industrial and environmental settings, where sensor performance must remain consistent over extended periods. The sensor's ability to withstand repeated use without significant degradation makes it a valuable tool for ongoing monitoring tasks. The potential applications of the Cd-Ni/PANI sensor are broad and impactful. In environmental monitoring, the sensor can detect NH₃ emissions from industrial and agricultural sources, helping to ensure compliance with environmental regulations and protect public health. In industrial safety, the sensor can monitor NH₃ levels in chemical plants, refrigeration systems, and other settings where NH₃ is used or produced, thereby preventing hazardous leaks and ensuring a safe working environment. Looking to the future, several research directions and applications can be pursued to further enhance the performance and utility of the Cd-Ni/PANI sensor[ 44 ]. Optimizing the doping levels of cadmium, exploring advanced fabrication techniques like electrospinning or 3D printing, and developing miniaturized, portable sensors for continuous monitoring are promising avenues[ 45 ]. Investigating other doping elements and conductive polymers could lead to even better sensor performance. Moreover, assessing the environmental and health impacts of using cadmium-doped materials and conducting a comprehensive cost analysis for commercial production will be essential for the sustainable application and market viability of these sensors. Overall, the development of Cd-Ni/PANI nanocomposite sensors marks a significant step forward in NH₃ gas sensing technology, offering a robust and efficient solution for a wide range of practical applications. Declarations Conflict of interest: Authors have no conflict of interest Author Contribution Dhivyadharshini N: work, synthesis of polymer composite and characterization, manuscript writingVarun D S : work, synthesis of polymer composite and characterization, manuscript writingS Dilip Kumar: work, synthesis of polymer composite and characterization, manuscript writingDr. Basavaraj R J: GuidanceDr.Vishnumurthy KA : work, synthesis of polymer composite and characterization, analysis, guidance, manuscript writing Acknowledgement: Authors are grateful for RV College of Engineering for providing opportunity to carryout this research work. References Mimani T, Patil KC SOLUTION COMBUSTION SYNTHESIS OF NANOSCALE OXIDES AND THEIR COMPOSITES Aruna ST, Mukasyan AS (2008) Combustion synthesis and nanomaterials, Curr. Opin. Solid State Mater. 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Mater Sci Semicond Process 137:106221. 10.1016/j.mssp.2021.106221 Wang J, Yang P, Wei X, Zhou Z (Dec. 2015) Preparation of NiO two-dimensional grainy films and their high-performance gas sensors for ammonia detection. Nanoscale Res Lett 10. 10.1186/s11671-015-0807-5 Levy D, Zayat M (2015) The Sol-Gel Handbook, 3 Volume Set: Synthesis, Characterization, and Applications. Wiley Rao BS, Reddy VR, Kumar BR, Rao TS, SYNTHESIS AND CHARACTERIZATION OF NICKEL DOPED CdS NANOPARTICLES (2012) Jun.,, Int. J. Nanosci. , vol. 11, no. 03, p. 1240006, 10.1142/S0219581X12400066 Zhang C, Xu K, Liu K, Xu J, Zheng Z (Dec. 2022) Metal oxide resistive sensors for carbon dioxide detection. Coord Chem Rev 472:214758. 10.1016/j.ccr.2022.214758 (PDF) Gas sensing mechanism of metal oxides: The role of ambient atmosphere, type of semiconductor and gases -A review. Accessed: May 14, 2024. [Online]. Available: https://www.researchgate.net/publication/270587471_Gas_sensing_mechanism_of_metal_oxides_The_role_of_ambient_atmosphere_type_of_semiconductor_and_gases_-A_review Highly Sensitive and Selective Gas Sensors Based on NiO/MnO2@NiO Nanosheets to Detect Allyl Mercaptan Gas Released by Humans under Psychological Stress - Li – 2022 - Advanced Science - Wiley Online Library. Accessed: Jun. 01, 2024. [Online]. Available: https://onlinelibrary.wiley.com/doi/ 10.1002/advs.202202442 Ahmad T, Khatoon S, Coolahan K (2016) Structural, Optical, and Magnetic Properties of Nickel-Doped Tin Dioxide Nanoparticles Synthesized by Solvothermal Method. J Am Ceram Soc 99(4):1207–1211. 10.1111/jace.14088 Mugutkar AB et al (2022) Jun., Ammonia gas sensing and magnetic permeability of enhanced surface area and high porosity lanthanum substituted Co–Zn nano ferrites, Ceram. Int. , vol. 48, no. 11, pp. 15043–15055, 10.1016/j.ceramint.2022.02.033 (1) (PDF) Synthesis of metal and metal oxide nanostructures and their application for gas sensing. Accessed: May 28, 2024. [Online]. Available: https://www.researchgate.net/publication/215901610_Synthesis_of_metal_and_metal_oxide_nanostructures_and_their_application_for_gas_sensing (1) Synthesis of polyaniline (printable nanoink) gas sensor for the detection of ammonia gas | Request PDF. Accessed: May 24, 2024. [Online]. Available: https://www.researchgate.net/publication/345796075_Synthesis_of_polyaniline_printable_nanoink_gas_sensor_for_the_detection_of_ammonia_gas Kanan S et al (2024) Mar., Recent Advances on Metal Oxide Based Sensors for Environmental Gas Pollutants Detection, Crit. Rev. Anal. Chem. , pp. 1–34, 10.1080/10408347.2024.2325129 Guruvammal D, Selvaraj S, Meenakshi Sundar S (Oct. 2016) Effect of Ni-doping on the structural, optical and magnetic properties of ZnO nanoparticles by solvothermal method. J Alloys Compd 682:850–855. 10.1016/j.jallcom.2016.05.038 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4514715","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":313457163,"identity":"4b1726f7-51a5-4ac3-a337-b55b35d1370f","order_by":0,"name":"Dr.Vishnumurthy 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18:38:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4514715/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4514715/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":58752712,"identity":"fad63a86-1a91-4705-a02e-8df77bfc9458","added_by":"auto","created_at":"2024-06-20 16:15:15","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":71943,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic representation of NiO synthesis by Solution Combustion Synthesis (SCS)\u003c/p\u003e","description":"","filename":"Picture1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4514715/v1/5ec3182d8624ec443c93d997.jpg"},{"id":58752709,"identity":"47e1fae4-903f-4e8a-a55c-8670891427af","added_by":"auto","created_at":"2024-06-20 16:15:15","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":115924,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of \u003cstrong\u003ea)\u003c/strong\u003e CdO, \u003cstrong\u003eb) \u003c/strong\u003e5% Cd doped NiO, \u003cstrong\u003ec)\u003c/strong\u003e10% Cd doped NiO and \u003cstrong\u003ed)\u003c/strong\u003e 15% Cd doped NiO\u003c/p\u003e","description":"","filename":"Picture2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4514715/v1/510769209532a2c9de34686d.jpg"},{"id":58752710,"identity":"070d95b7-e5a6-40a2-8e5f-6bc56bed0825","added_by":"auto","created_at":"2024-06-20 16:15:15","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":77268,"visible":true,"origin":"","legend":"\u003cp\u003eXRD images of \u003cstrong\u003ea)\u003c/strong\u003e CdO, \u003cstrong\u003eb) \u003c/strong\u003e5% Cd doped NiO, \u003cstrong\u003ec)\u003c/strong\u003e10% Cd doped NiO and \u003cstrong\u003ed)\u003c/strong\u003e 15% Cd doped NiO\u003c/p\u003e","description":"","filename":"Picture3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4514715/v1/6547708a6f949a433a59c650.jpg"},{"id":58752713,"identity":"f123a2ba-3f46-42ee-9857-85edc4518c18","added_by":"auto","created_at":"2024-06-20 16:15:15","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":37772,"visible":true,"origin":"","legend":"\u003cp\u003eNH\u003csub\u003e3\u003c/sub\u003e Sensing Performance of CdO and Cd-Doped NiO at 5PPM\u003c/p\u003e","description":"","filename":"Picture4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4514715/v1/bf7ec4b5c2ff9b464ec27119.jpg"},{"id":58752711,"identity":"7b663df9-304e-4c22-9551-e81df3fde423","added_by":"auto","created_at":"2024-06-20 16:15:15","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":60513,"visible":true,"origin":"","legend":"\u003cp\u003eNH\u003csub\u003e3\u003c/sub\u003e Sensing Performance of 10% Cadmium-Doped NiO and Polyaniline Composite at 5,10,15 and 20 PPM Concentrations\u003c/p\u003e","description":"","filename":"Picture5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4514715/v1/6b2ec3d4fdff610170a137f3.jpg"},{"id":58752714,"identity":"0edb4189-e70f-496b-9fdc-4ed691f81a13","added_by":"auto","created_at":"2024-06-20 16:15:16","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":64954,"visible":true,"origin":"","legend":"\u003cp\u003eNH\u003csub\u003e3\u003c/sub\u003e Sensing Performance of 15% Cadmium-Doped NiO and Polyaniline Composite at 5,10,15 and 20 PPM Concentrations\u003c/p\u003e","description":"","filename":"Picture6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4514715/v1/d389a5a1690c86f0ea74b915.jpg"},{"id":59167041,"identity":"93fc7943-95f5-418e-9be0-52c6fc97c9c3","added_by":"auto","created_at":"2024-06-27 07:46:28","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":854160,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4514715/v1/788da31f-1d8e-4b30-856b-906c104431f6.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Development of Cadmium doped Nickel polymer nano composites for enhanced NH₃ gas sensing applications","fulltext":[{"header":"1.0 Introduction","content":"\u003cp\u003eA chemical gas sensor can be defined as a device, which upon exposure to gaseous species or molecules, alters one or more of its physical properties, such as mass, electrical conductivity, or dielectric properties, in a way that is possible to measure and quantify. The device should also show a reverse property after the gas has been removed[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Gas sensors based on bulk materials or dense films face a tremendous challenge in achieving highly-sensitive properties, as the morphology and structure of the sensing materials greatly impact the sensors' performance. Nanomaterial-based gas sensors represent a rapidly emerging avenue for enhancing the sensitivity, selectivity, and reaction speed of gas sensing capabilities. A thorough summary of the characteristics of metal oxides from the standpoint of nanoscience and nanotechnology is still required, despite the fact that there have already been a few studies on metal oxide gas sensors[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. In recent years, the rapid industrialization and intensification of agricultural activities have led to an increase in the emission of hazardous gases, posing significant challenges to environmental sustainability and public health. Among these gases, ammonia (NH\u003csub\u003e3\u003c/sub\u003e) stands out as a prominent pollutant, originating from sources such as livestock farming, fertilizer application, and industrial processes. The need for sensitive, selective, and reliable NH\u003csub\u003e3\u003c/sub\u003e gas sensors has become increasingly urgent to enable effective monitoring and control of NH\u003csub\u003e3\u003c/sub\u003e emissions in various settings, including agricultural, industrial, and environmental contexts[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. In response to these challenges, the present study focuses on the development of innovative gas sensing materials based on cadmium-doped nano composites. Cadmium, with its unique electronic and chemical properties, offers promising opportunities for enhancing the performance of gas sensors, including sensitivity to NH\u003csub\u003e3\u003c/sub\u003e and selectivity against interfering gases. Ammonia (NH₃) is a crucial industrial chemical extensively used in various applications, including fertilizers, pharmaceuticals, and refrigeration systems. Despite its widespread utility, ammonia poses significant health and environmental risks due to its high toxicity and volatility. Prolonged exposure to NH₃ can cause severe respiratory issues and environmental pollution, making its detection and monitoring essential in both industrial and environmental settings[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Thus, developing sensitive, selective, and reliable NH₃ gas sensors has garnered considerable interest in recent years.\u003c/p\u003e \u003cp\u003eNickel-based nanocomposites have emerged as promising candidates for gas sensing applications due to their unique electrical, thermal, and catalytic properties. Nickel (Ni) nanoparticles, owing to their high surface area-to-volume ratio, exhibit enhanced chemical reactivity and electron mobility, which are critical for effective gas sensing. These nanocomposites detect gas molecules through changes in electrical resistance, making them suitable for developing robust and efficient gas sensors[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. However, to achieve the desired sensitivity and selectivity for NH₃ detection, further modifications and enhancements of these nanocomposites are necessary.\u003c/p\u003e \u003cp\u003eDoping is a well-established strategy to enhance the properties of nanomaterials. By introducing foreign atoms into the host material's lattice structure, the electronic and catalytic properties can be significantly altered, leading to improved sensor performance[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Cadmium (Cd) doping in nickel nanocomposites is particularly intriguing due to Cd's potential to modify the electronic structure and surface chemistry of Ni, thereby enhancing its interaction with NH₃ molecules[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. The addition of Cd can create more active sites and alter the charge distribution on the surface of the Ni nanoparticles, leading to increased adsorption of NH₃ molecules and improved sensor response. Polyaniline (PANI), a conducting polymer, has gained attention for its excellent electrical properties, environmental stability, and ease of synthesis. Blending Ni-based nanocomposites with PANI can further enhance the gas sensing capabilities. The synergy between Ni nanoparticles and PANI could lead to improved sensor performance due to the combined effects of high surface area, conductivity, and the unique sensing properties of PANI. PANI can act as a matrix, providing a conducive environment for electron transfer and enhancing the overall sensitivity and selectivity of the sensor[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThis study aims to develop cadmium-doped nickel (Cd-Ni) nanocomposites blended with polyaniline (PANI) and investigate their potential for NH₃ gas sensing applications. The primary objectives are to: (1) synthesize Cd-Ni/PANI nanocomposites using a solution combustion method, (2) characterize the structural, morphological, and compositional properties of the synthesized nanocomposites, and (3) evaluate the gas sensing performance of the Cd-Ni/PANI nanocomposites in terms of sensitivity, selectivity, response time, and recovery time[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The significance of this research lies in its potential to contribute to the development of highly sensitive and selective NH₃ gas sensors. By enhancing the performance of Ni-based sensors through Cd doping and PANI blending, this work aims to address the current limitations in NH₃ detection technologies and pave the way for their broader application in industrial and environmental monitoring.\u003c/p\u003e \u003cp\u003eThe solution combustion Synthesis (SCS) is a versatile and efficient technique for synthesizing nanocomposites. It involves an exothermic redox reaction between a fuel (e.g., urea) and an oxidizer (e.g., metal nitrates) in an aqueous solution, leading to the formation of nanostructured materials[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. This method offers several advantages, including simplicity, cost-effectiveness, and the ability to produce highly crystalline materials with controlled morphologies. In this study, nickel nitrate (Ni(NO₃)₂), cadmium nitrate (Cd(NO₃)₂), and aniline will be used as precursors, with urea acting as the fuel[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The combustion process will result in the formation of Cd-doped Ni nanocomposites, which will subsequently be blended with PANI. The doping concentration of Cd and the ratio of PANI will be systematically varied to optimize the nanocomposites' properties for NH₃ gas sensing.\u003c/p\u003e \u003cp\u003eThe gas sensing performance of the Cd-Ni/PANI nanocomposites will be evaluated in a controlled environment. Key parameters such as sensitivity, selectivity, response time, and recovery time will be measured. The sensors' response will be tested over a range of NH₃ concentrations to determine their detection limits and linearity. Additionally, the selectivity of the sensors will be assessed by exposing them to other common gases such as CO₂, H₂, and CH₄[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The incorporation of Cd and PANI is expected to enhance the interaction between the nanocomposite and NH₃ molecules, leading to improved performance metrics. The improved sensing performance of Cd-Ni/PANI nanocomposites can be attributed to several factors[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. The Cd doping introduces new active sites and modifies the electronic structure of Ni, enhancing NH₃ adsorption. The PANI matrix further contributes to this enhancement by providing a highly conductive pathway for electron transfer, which is crucial for rapid response and recovery times. The interaction between NH₃ molecules and the nanocomposite induces changes in the electrical properties of PANI, leading to measurable variations in resistance[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe presence of PANI also improves the sensor's selectivity by enhancing the affinity for NH₃ over other gases[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. This can be explained by the specific interaction between NH₃ and the nitrogen atoms in PANI, which forms hydrogen bonds, further increasing NH₃ adsorption. Additionally, the unique porous structure of PANI allows for effective gas diffusion, ensuring that NH₃ molecules reach the active sites on the Ni nanoparticles.\u003c/p\u003e \u003cp\u003eFrom the foregoing literature it has been planned to design poly aniline-nano composites based senor with nickel doped cadmium nano particles for selective recognition of ammonia vapor.\u003c/p\u003e"},{"header":"2.0 Materials and methods","content":"\u003cp\u003eAll the required chemicals are purchased from Sigma Aldrich India and used without purification.\u003c/p\u003e\n\u003cdiv id=\"Sec3\"\u003e\n \u003ch2\u003e2.1. Solution Combustion Synthesis:\u003c/h2\u003e\n \u003cp\u003eNickel oxide (NiO) was synthesized using solution combustion synthesis (SCS) with nickel nitrate hexahydrate (Ni (NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e\u0026sdot; 6H\u003csub\u003e2\u003c/sub\u003eO) as the oxidizer and urea (NH\u003csub\u003e2\u003c/sub\u003eCONH\u003csub\u003e2\u003c/sub\u003e) as the fuel. The precursor solution was prepared by dissolving stoichiometric amounts of nickel nitrate and urea in distilled water to form a homogeneous mixture[\u003cspan\u003e16\u003c/span\u003e]. The homogeneous precursor solution was then transferred to a beaker suitable for high-temperature reactions. The beaker containing the precursor solution was placed on a hot plate with continuous Stirring to evaporate water molecules and gradually heated to induce ignition. Then after certain time when mixture turned into paste like consistency then the mixture is transferred to combustion chamber. The solution underwent a self-sustaining and exothermic combustion reaction, characterized by a vigorous release of gases including nitrogen (N\u003csub\u003e2\u003c/sub\u003e), carbon dioxide (CO\u003csub\u003e2\u003c/sub\u003e), and water vapor (H\u003csub\u003e2\u003c/sub\u003eO), resulting in the formation of a voluminous and porous NiO powder[\u003cspan\u003e17\u003c/span\u003e]. Following the combustion process, the powder was allowed to cool to room temperature and then subjected to calcination at 450\u0026ndash;500\u0026deg;C for 1\u0026ndash;2 hours to enhance crystallinity and remove residual organic content. This calcination process not only enhanced the structural integrity of the NiO nanoparticles but also ensured their purity. All these steps are illustrated in Fig. \u003cspan\u003e1\u003c/span\u003e for NiO nanoparticles from (Ni (NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e\u0026sdot; 6H\u003csub\u003e2\u003c/sub\u003eO) using urea as fuel.\u003c/p\u003e\n \u003cp\u003eIn SCM, a fuel (typically an organic compound like urea) and an oxidizer (such as a metal nitrate) are dissolved in a solvent. The combustion reaction is driven by the redox interaction between these components, where the fuel acts as a reductant, and the metal nitrate serves as the oxidant[\u003cspan\u003e18\u003c/span\u003e]. The calculation of fuel/oxidizer ratio (\u0026Phi;) for the synthesis of nickel oxide by solution combustion synthesis is given below. Nickel nitrate as the oxidizer and urea as the fuel are used. It is assumed that H₂O, CO₂ and N₂ are the gaseous products formed in the combustion reaction. Initially, it is considered the balance of nickel nitrate decomposition reaction (Eq.\u0026nbsp;(1)) and fuel (urea) oxidation reaction (Eq.\u0026nbsp;(2))\u003c/p\u003e\n \u003cp\u003eNi(NO₃)₂.6H₂O \u0026rarr; NiO\u0026thinsp;+\u0026thinsp;6H₂O\u0026thinsp;+\u0026thinsp;N₂ + (5/2) O₂ ...............................................................(1)\u003c/p\u003e\n \u003cp\u003enCO(NH₂)₂ + (3/2) nO₂ \u0026rarr; 2nH₂O\u0026thinsp;+\u0026thinsp;nCO₂ + nN₂ .............................................................(2)\u003c/p\u003e\n \u003cp\u003eThe overall reaction (Eq.\u0026nbsp;(3)) is given by the combination of Eqs.\u0026nbsp;(1) and (2)\u003c/p\u003e\n \u003cp\u003eNi(NO₃)₂.6H₂O\u0026thinsp;+\u0026thinsp;nCO(NH₂)₂ + (5/2) [(3/5) n\u0026thinsp;\u0026minus;\u0026thinsp;1] O₂ \u0026rarr;\u003c/p\u003e\n \u003cp\u003eNiO\u0026thinsp;+\u0026thinsp;2(n\u0026thinsp;+\u0026thinsp;3)H₂O\u0026thinsp;+\u0026thinsp;nCO₂ + (n\u0026thinsp;+\u0026thinsp;1)N₂ .................................(3)\u003c/p\u003e\n \u003cdiv id=\"Sec4\"\u003e\n \u003ch2\u003e2.1.1. Experimental Procedure:\u003c/h2\u003e\n \u003cp\u003eTo synthesize nickel oxide (NiO) via solution combustion synthesis (SCS), begin by preparing the required materials: nickel nitrate (Ni(NO₃)₂), urea (CO(NH₂)₂), and distilled water[\u003cspan\u003e18\u003c/span\u003e]. Using an analytical balance, accurately weigh 8 grams of nickel nitrate and 2.75 grams of urea. This step marks the initiation of the reaction precursor solution, laying the groundwork for the ensuing combustion process that will lead to the formation of nickel oxide. With the precursor solution prepared, the stage is set for the combustion reaction[\u003cspan\u003e20\u003c/span\u003e]. Initiating the combustion typically involves heating the solution to trigger the exothermic reaction between the metal nitrate and the fuel (urea). After combustion, the NiO nanoparticles yield is 0.56g\u003c/p\u003e\n \u003cp\u003eDoping nickel oxide (NiO) with cadmium (Cd) can significantly enhance its properties, particularly for applications in gas sensing. Cadmium doping can modify the electronic structure and surface characteristics of NiO, leading to improved sensitivity, selectivity, and response times for gas sensors, especially for detecting gases such as ammonia (NH₃)[\u003cspan\u003e21\u003c/span\u003e]. In present work 5, 10 and 15% doping of cadmium was done with nickel. And prepared nano materials are used in the preparation of nano composite sensors.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec5\"\u003e\n \u003ch2\u003e2.1.2. Polyaniline Synthesis:\u003c/h2\u003e\n \u003cp\u003ePolyaniline (PANI) is synthesized due to its unique combination of high electrical conductivity, environmental stability, and ease of synthesis[\u003cspan\u003e22\u003c/span\u003e]. It is a versatile conducting polymer that can be produced through chemical polymerization, making it suitable for various applications. One of the key uses of PANI is in gas sensing applications. PANI\u0026apos;s high surface area, tunable conductivity, and ability to interact with gas molecules through redox reactions make it an excellent material for detecting gases such as ammonia (NH₃)[\u003cspan\u003e8\u003c/span\u003e]. When incorporated into gas sensors, PANI provides high sensitivity, fast response times, and good selectivity, making it valuable for environmental monitoring, industrial safety, and health diagnostics.\u003c/p\u003e\n \u003cp\u003eIn a beaker or flask, dissolve 5ml of aniline in 1 M hydrochloric acid (HCl) to form an aniline hydrochloride solution. Dissolve 24g ammonium persulfate (APS) in distilled water to prepare the oxidant solution[\u003cspan\u003e23\u003c/span\u003e]. Place the aniline hydrochloride solution in an ice bath to maintain a low temperature (0\u0026ndash;5\u0026deg;C) during the polymerization process. This helps control the reaction rate and improve the quality of the polyaniline. Slowly add the APS solution to the aniline hydrochloride solution with constant stirring using a magnetic stirrer. The addition should be done dropwise to avoid a rapid increase in temperature. Continue stirring the mixture in the ice bath for 4\u0026ndash;6 hours to ensure complete polymerization[\u003cspan\u003e24\u003c/span\u003e]. The solution will gradually turn dark green, indicating the formation of polyaniline. The final product which is Polyaniline is filtered using Buchner Filter and then it has been dried at 50\u003csup\u003e0\u003c/sup\u003eC in hot air oven for 2\u0026ndash;3 hrs. The yield of Polyaniline is 10.76g.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv id=\"Sec6\"\u003e\n \u003ch2\u003e2.1.3. Characterisation:\u003c/h2\u003e\n \u003cp\u003eCharacterization of nickel oxide (NiO) nanoparticles involves X-ray diffraction (XRD) to determine crystalline structure, lattice parameters, and phase purity, aiding in identifying crystalline phases[\u003cspan\u003e26\u003c/span\u003e]. Scanning electron microscopy (SEM) complements by revealing surface morphology, particle size distribution, and agglomeration behavior at high resolution. XRD patterns display diffraction peaks corresponding to specific crystallographic planes, crucial for crystallinity assessment. SEM imaging provides insights into nanoparticle shape, size, and agglomeration through electron beam scanning and secondary electron detection[\u003cspan\u003e27\u003c/span\u003e]. Elemental analysis via energy-dispersive X-ray spectroscopy (EDS) integrated with SEM confirms elemental composition[\u003cspan\u003e28\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eSEM Analysis:\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e(a) The scanning electron microscopy (SEM) analysis of cadmium oxide (CdO) nanoparticles synthesized via solution combustion synthesis reveals predominantly cubic and polyhedral shapes with sizes typically ranging from 100 nm to 300 nm. The particles exhibit significant aggregation, forming larger agglomerates with a rough surface texture and well-defined faceted edges, indicative of high crystallinity. Porosity within the agglomerates, characterized by visible voids and gaps, suggests an enhanced surface area, beneficial for gas sensing applications. These structural features, including the high surface area and rough texture, are ideal for applications such as ammonia (NH₃) detection, potentially improving sensitivity and response time. Thus, the SEM analysis confirms that the synthesized CdO nanoparticles possess the necessary attributes for effective gas sensing, validating their potential for practical sensor development.\u003c/p\u003e\n \u003cp\u003e(b) The SEM analysis of the 5% cadmium-doped nickel oxide sample, produced through solution combustion synthesis, shows mainly spherical particles with sizes ranging from 100 to 150nm. These particles have a relatively smooth surface texture and exhibit significant agglomeration, forming dense clusters typical of this synthesis method. The uniform particle size distribution indicates effective cadmium doping and homogeneous mixing within the nickel oxide matrix. Additionally, visible porosity, with gaps and voids between agglomerated particles, suggests potential for high surface area applications, such as catalysis, sensors, and energy storage. Overall, the observed morphology aligns with expectations for doped nickel oxide materials prepared using this synthesis technique.\u003c/p\u003e\n \u003cp\u003e(c)\u0026nbsp;The SEM analysis of the 10% cadmium-doped nickel oxide sample, synthesized via solution combustion, reveals predominantly spherical particles with sizes ranging from 100-200nm. The particles exhibit a relatively smooth surface texture and significant agglomeration, forming clusters typical of nanoparticles synthesized through this method. The uniform spherical shape and consistent size distribution indicate effective doping and mixing of cadmium into the nickel oxide matrix. Additionally, the presence of some porosity, with visible gaps and voids between agglomerated particles, suggests potential applications requiring high surface areas, such as catalysis, sensors, or energy storage materials. Overall, the SEM image demonstrates a successful synthesis with desirable morphological characteristics for various advanced applications.\u003c/p\u003e\n \u003cp\u003e(d) The SEM image of 15% cadmium-doped nickel oxide synthesized by solution combustion synthesis reveals a nanostructured morphology with predominantly spherical nanoparticles. The particles appear to be uniformly distributed, with a significant degree of agglomeration, indicative of high surface energy and interactions among the nanoparticles. The average particle size is estimated to be within the sub-micrometer range, with many particles exhibiting sizes below 150 nanometers. The image also shows a relatively consistent particle size distribution, suggesting a controlled synthesis process. The high magnification and resolution of the SEM allow for the observation of fine surface details, indicating that the doping process has been successful without significant alteration to the inherent nanostructured characteristics of the nickel oxide matrix. This homogeneity and nanoscale morphology are critical for applications requiring high surface area and uniformity, such as in sensors or catalysis.\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eXRD analysis:\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003ea) The XRD pattern of the synthesized cadmium oxide (CdO) nanoparticles \u0026quot;3a)\u0026quot; exhibits sharp peaks at approximately 33\u0026deg;, 38\u0026deg;, 55\u0026deg;, 66\u0026deg;, and 69\u0026deg;, corresponding to the (111), (200), (220), (311), and (222) planes of cubic CdO as per JCPDS Card No. 05-0640. The observed peak positions and intensities confirm the high crystallinity and phase purity of the CdO nanoparticles. The absence of additional peaks indicates that the sample is free from impurities, validating the successful synthesis of pure CdO with a well-defined cubic crystal structure.\u003c/p\u003e\n \u003cp\u003eb) The XRD pattern of 5% cadmium-doped nickel oxide (NiO) nanoparticles, labeled \u0026quot;3b)\u0026quot; shows distinct peaks at approximately 37.3\u0026deg;, 43.4\u0026deg;, 63.1\u0026deg;, 75.5\u0026deg;, and 79.6\u0026deg;, corresponding to the (111), (200), (220), (311), and (222) planes of NiO as per JCPDS Card No. 04-0835. These peaks confirm that the crystalline structure of NiO is retained even with 5% cadmium doping. The sharpness of the peaks indicates good crystallinity of the doped nanoparticles. The slight shifts in peak positions relative to pure NiO are due to lattice distortions caused by the incorporation of cadmium atoms. The absence of additional peaks suggests that the sample is highly crystalline and free from significant impurities, validating the successful incorporation of cadmium into the NiO lattice.\u003c/p\u003e\n \u003cp\u003ec) The XRD pattern of 10% cadmium-doped nickel oxide (NiO) nanoparticles, labeled \u0026quot;3c)\u0026quot; shows distinct peaks at approximately 37.2\u0026deg;, 43.3\u0026deg;, 63.0\u0026deg;, 75.4\u0026deg;, and 79.4\u0026deg;, corresponding to the (111), (200), (220), (311), and (222) planes of NiO as per JCPDS Card No. 04-0835. These peaks confirm that the crystalline structure of NiO is retained even with 10% cadmium doping. The sharpness of the peaks indicates good crystallinity of the doped nanoparticles. The slight shifts in peak positions relative to pure NiO are due to lattice distortions caused by the incorporation of cadmium atoms. The absence of additional peaks suggests that the sample is highly crystalline and free from significant impurities, validating the successful incorporation of cadmium into the NiO lattice.\u003c/p\u003e\n \u003cp\u003ed) The XRD pattern of 15% cadmium-doped nickel oxide (NiO) nanoparticles, labeled \u0026quot;3d)\u0026quot; reveals distinct peaks at approximately 37\u0026deg;, 43\u0026deg;, 63\u0026deg;, 75\u0026deg;, and 79\u0026deg;, corresponding to the (111), (200), (220), (311), and (222) planes of NiO as per JCPDS Card No. 04-0835. These peaks confirm that the crystalline structure of NiO is retained even with 15% cadmium doping. The sharpness of the peaks indicates good crystallinity of the doped nanoparticles. Any slight shifts in peak positions relative to pure NiO might be due to lattice distortions caused by the incorporation of cadmium atoms. The absence of additional peaks suggests that the sample is highly crystalline and free from significant impurities, validating the successful incorporation of cadmium into the NiO lattice.\u0026nbsp;\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\"\u003e\n \u003ch2\u003e2.2. Composite Preparation and Blending:\u003c/h2\u003e\n \u003cp\u003eThe doping concentrations of both PANI in NiO and Cadmium in PANI can be varied systematically, such as 5%, 10%, and 15%, to study their effects on the properties of the composite thin film[\u003cspan\u003e29\u003c/span\u003e]. By varying the doping concentration of PANI in NiO, the properties of the composite thin films can be tailored to meet specific requirements for sensor applications. Higher doping concentrations may result in increased conductivity and sensitivity, while lower concentrations may offer improved stability or selectivity[\u003cspan\u003e30\u003c/span\u003e]. The ability to control doping concentration provides flexibility in designing composite materials with enhanced performance for various sensor platforms.\u003c/p\u003e\n \u003cp\u003eDoctor blade coating:\u003c/p\u003e\n \u003cp\u003eThe doctor blade technique is a well-established method for fabricating thin films, valued for its simplicity and versatility. The process begins by placing a blended solution of materials, such as a mixture of nickel oxide (NiO) nanoparticles and Cd doped NiO nanoparticles and polyaniline (PANI), onto a substrate. Common substrates include glass, flexible polymers, thick paper. The choice of substrate depends on the intended application of the thin film. Here\u003c/p\u003e\n \u003cp\u003ePaper has been chosen as our substrate. The critical step in the doctor blade technique is the spreading of the solution. This is achieved using a blade, often made of metal or glass, which is set at a fixed height above the substrate. The gap between the blade and the substrate determines the thickness of the film[\u003cspan\u003e31\u003c/span\u003e]. By adjusting this gap, one can precisely control the film thickness, typically ranging from a few microns to several hundred microns. This control is essential for applications requiring specific film properties, such as in sensors, batteries, etc.\u003c/p\u003e\n \u003cp\u003eThe viscosity of the solution also plays a crucial role in determining the final film characteristics. A higher viscosity solution will generally produce thicker films, while a lower viscosity solution will spread more thinly. To achieve the desired viscosity, the solution can be adjusted by altering the concentration of the components or by adding solvents. Ensuring a uniform viscosity is vital for producing consistent and defect-free films. After spreading the solution, the substrate is allowed to dry[\u003cspan\u003e32\u003c/span\u003e]. Drying can be done at room temperature or under controlled conditions, such as in an oven or using a heat lamp, to accelerate the process. The drying method can affect the film\u0026apos;s final properties, including its adhesion to the substrate and its mechanical strength. For instance, slower drying rates might result in more uniform films with fewer internal stresses, while faster drying can reduce processing time but may introduce defects.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"3.0 Results and discussion","content":"\u003cp\u003eAmmonia gas sensing using Arduino often involves gas sensors like MQ series sensors, which typically output resistance values that vary with the concentration of ammonia gas in the environment. These sensors are vital in numerous applications, including environmental monitoring, industrial safety, and agriculture, where tracking ammonia levels is essential for various purposes. In the hardware setup, the ammonia gas sensor is connected to the Arduino board. These sensors often provide resistance values as output, which change in response to varying concentrations of ammonia gas. Calibration of the sensor is crucial to establish a relationship between the sensor's resistance values and the actual concentrations of ammonia gas. The software setup involves writing Arduino code to read resistance values from the sensor over time. This data is then processed to convert resistance values to corresponding ammonia gas concentrations using a calibration curve. The Arduino code can log this data over time or display it on the serial monitor for real-time monitoring[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDuring the experiment, the sensor is placed in the desired location, and the Arduino code is executed. Ammonia gas is introduced into the environment in controlled concentrations, such as 5 ppm, 10 ppm, and 15 ppm, using calibrated sources. The resistance values obtained from the sensor over time are recorded and analyzed. Interpreting the experiment involves analyzing the relationship between the sensor's resistance values and the known concentrations of ammonia gas introduced. By correlating the resistance values with the calibrated concentrations, researchers can evaluate the sensor's sensitivity and accuracy[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. Adjustments to the calibration curve or sensor placement may be necessary to improve the accuracy of future measurements. Additionally, safety precautions should be taken when handling ammonia gas, and proper ventilation should be ensured during the experiment to prevent exposure to high concentrations.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe provided graphs represent the NH\u003csub\u003e3\u003c/sub\u003e sensing performance of Cadmium Oxide (CdO) and various doping levels (5%, 10%, and 15%) of Cadmium-doped Nickel Oxide (NiO) under a 5 ppm concentration of ammonia gas. These measurements were taken using Arduino software version 1.8.16, showcasing resistance changes over time as the materials interact with the ammonia gas.\u003c/p\u003e \u003cp\u003eThe 5 ppm - CdO graph, the resistance changes from approximately 14 MΩ to 22 MΩ over a period of about 2000 seconds. This graph indicates that CdO has a noticeable response to NH\u003csub\u003e3\u003c/sub\u003e, with several peaks suggesting periods of gas exposure and subsequent recovery. The sensitivity of the material can be observed from the significant changes in resistance upon exposure to NH\u003csub\u003e3\u003c/sub\u003e. The response time, the time taken for the sensor to reach its peak resistance, appears to be relatively short, occurring within 1 to 2 seconds. The recovery time, the period for the sensor to return to its baseline resistance, seems to be consistent but not immediate, suggesting moderate adsorption and desorption rates of NH\u003csub\u003e3\u003c/sub\u003e on CdO.\u003c/p\u003e \u003cp\u003eFor the 5 ppm \u0026ndash; 5% Cd doped NiO-PANI graph, the resistance varies between 19.8 MΩ and 21 MΩ over the same duration of 2000 seconds. The fluctuations in resistance indicate a high sensitivity to NH\u003csub\u003e3\u003c/sub\u003e, with sharper peaks compared to CdO. The response time is quick, as shown by the rapid rise in resistance upon exposure to NH\u003csub\u003e3\u003c/sub\u003e, followed by a steady recovery period. The repeated peaks imply that the sensor is highly responsive and capable of returning to baseline resistance efficiently, indicating good recovery characteristics.\u003c/p\u003e \u003cp\u003eExamining the 5 ppm \u0026minus;\u0026thinsp;10% Cd doped NiO-PANI graph, the resistance spans from approximately 7 MΩ to 14 MΩ over a longer period of 3000 seconds. This extended duration provides a detailed view of the sensor's performance under prolonged exposure to NH\u003csub\u003e3\u003c/sub\u003e. The significant drops and rises in resistance reflect high sensitivity to ammonia, with a clear pattern of response and recovery. The response time is observable within the initial phase of exposure, while the recovery time, though evident, appears more gradual compared to the 5% doping level. This suggests that 10% NiO-PANI has a strong interaction with NH\u003csub\u003e3\u003c/sub\u003e, albeit with a slightly longer desorption period.\u003c/p\u003e \u003cp\u003eFinally, the 5 ppm \u0026minus;\u0026thinsp;15% Cd doped NiO-PANI graph demonstrates resistance variations between 14 MΩ and 30 MΩ over 1500 seconds. The higher resistance range indicates a substantial sensitivity to NH\u003csub\u003e3\u003c/sub\u003e, with pronounced peaks illustrating effective response upon gas exposure. The response time is swift, marked by immediate changes in resistance, whereas the recovery time, though present, shows more variability. This could suggest that at 15% doping, the material's surface interaction with NH\u003csub\u003e3\u003c/sub\u003e is highly active but may lead to a less consistent recovery process.\u003c/p\u003e \u003cp\u003eThe sensitivity of the sensors increases with higher doping levels, as shown by more significant resistance changes. The response times across all samples are relatively quick, indicating good immediate interaction with NH\u003csub\u003e3\u003c/sub\u003e. However, the recovery times vary, with higher doping levels showing more variability and longer recovery periods. This variability might be due to the increased surface interaction sites available in higher doping levels, which can lead to stronger adsorption of ammonia molecules and hence longer desorption times. Each material's performance showcases the trade-offs between sensitivity and recovery characteristics, essential factors in designing effective NH\u003csub\u003e3\u003c/sub\u003e sensors.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe 10% cadmium-doped NiO and polyaniline (PANI) composite sensor was exposed to NH\u003csub\u003e3\u003c/sub\u003e vapor with concentrations of 5, 10, 15, and 20 ppm, and the resulting variations in resistance as a function of time were recorded (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). The resistance of the NiO-PANI gas sensor increased significantly upon exposure to NH\u003csub\u003e3\u003c/sub\u003e vapor. When the NiO-PANI gas sensor was exposed to 20 ppm of NH\u003csub\u003e3\u003c/sub\u003e vapor, the resistance increased from 10 MΩ to approximately 15 MΩ, corresponding to a response of 50%. Furthermore, the resistance increased with an increase in the concentration of NH\u003csub\u003e3\u003c/sub\u003e vapor. The response increased monotonically from 20% at 5 ppm of NH\u003csub\u003e3\u003c/sub\u003e vapor to 50% at 20 ppm of NH\u003csub\u003e3\u003c/sub\u003e vapor, as shown in the Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. It should be even at low conc of around 2 or 3 ppm it senses NH3 gas making it very efficient as a gas sensor and also in detecting minor leakages.The sensitivity of the composite material to NH\u003csub\u003e3\u003c/sub\u003e was calculated using the percentage change in resistance. At 5 ppm, the resistance increased from 10 MΩ to 12 MΩ, resulting in a sensitivity of 20%. At 10 ppm, the resistance increased from 10 MΩ to 13 MΩ, resulting in a sensitivity of 30%. At 15 ppm, the resistance increased from 10 MΩ to 14 MΩ, resulting in a sensitivity of 40%. At 20 ppm, the resistance increased from 10 MΩ to 15 MΩ, resulting in a sensitivity of 50%. These values indicate a linear increase in sensitivity with increasing NH\u003csub\u003e3\u003c/sub\u003e concentration. This linearity is advantageous as it simplifies the calibration and interpretation of sensor data, making the sensor reliable for quantitative analysis. The response time, defined as the time taken for the resistance to rise from the baseline to the peak value after exposure to NH\u003csub\u003e3\u003c/sub\u003e, was consistently around 100 seconds for all concentrations. Similarly, the recovery time, defined as the time taken for the resistance to return from the peak value back to the baseline after NH\u003csub\u003e3\u003c/sub\u003e is removed, was also consistently around 100 seconds for all concentrations. This consistency in response and recovery times suggests that the material's interaction with NH\u003csub\u003e3\u003c/sub\u003e is stable and predictable.\u003c/p\u003e \u003cp\u003eThe composite material of 10% cadmium-doped NiO and polyaniline demonstrates excellent NH\u003csub\u003e3\u003c/sub\u003e sensing properties. The resistance change shows a linear relationship with NH\u003csub\u003e3\u003c/sub\u003e concentration, with sensitivities reaching up to 50% at 20 ppm. The consistent response and recovery times further highlight the material's suitability for practical NH\u003csub\u003e3\u003c/sub\u003e sensing applications. These findings suggest that the composite material is highly effective for detecting and quantifying NH\u003csub\u003e3\u003c/sub\u003e, making it a promising candidate for use in various fields requiring accurate and timely gas detection.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe 15% cadmium-doped NiO and polyaniline (PANI) composite sensor was exposed to NH\u003csub\u003e3\u003c/sub\u003e vapor with concentrations of 5, 10, 15, and 20 ppm, and the resulting variations in resistance as a function of time were recorded (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). The resistance of the NiO-PANI gas sensor increased significantly upon exposure to NH\u003csub\u003e3\u003c/sub\u003e vapor. When the NiO-PANI gas sensor was exposed to 20 ppm of NH\u003csub\u003e3\u003c/sub\u003e vapor, the resistance increased from 20 MΩ to approximately 35 MΩ, corresponding to a response of 75%. Furthermore, the resistance increased with an increase in the concentration of NH\u003csub\u003e3\u003c/sub\u003e vapor. The response increased monotonically from 10% at 5 ppm of NH\u003csub\u003e3\u003c/sub\u003e vapor to 75% at 20 ppm of NH\u003csub\u003e3\u003c/sub\u003e vapor, as shown in the Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eThe sensitivity of the composite material to NH\u003csub\u003e3\u003c/sub\u003e was calculated using the percentage change in resistance. At 5 ppm, the resistance increased from 20 MΩ to 22 MΩ, resulting in a sensitivity of 10%. At 10 ppm, the resistance increased from 20 MΩ to 25 MΩ, resulting in a sensitivity of 25%. At 15 ppm, the resistance increased from 20 MΩ to 30 MΩ, resulting in a sensitivity of 50%. At 20 ppm, the resistance increased from 20 MΩ to 35 MΩ, resulting in a sensitivity of 75%. These values indicate a linear increase in sensitivity with increasing NH\u003csub\u003e3\u003c/sub\u003e concentration. This linearity is advantageous as it simplifies the calibration and interpretation of sensor data, making the sensor reliable for quantitative analysis. 15% cadmium-doped NiO and polyaniline demonstrates excellent NH\u003csub\u003e3\u003c/sub\u003e sensing properties. The resistance change shows a linear relationship with NH\u003csub\u003e3\u003c/sub\u003e concentration, with sensitivities reaching up to 75% at 20 ppm. The consistent response and recovery times further highlight the material's suitability for practical NH\u003csub\u003e3\u003c/sub\u003e sensing applications. These findings suggest that the composite material is highly effective for detecting and quantifying NH\u003csub\u003e3\u003c/sub\u003e, making it a promising candidate for use in various fields requiring accurate and timely gas detection.\u003c/p\u003e \u003cp\u003eThe synthesized Cadmium-doped Nickel (Cd-Ni) nano composites with polyaniline were thoroughly characterized to assess their suitability for ammonia (NH₃) gas sensing applications[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. SEM analysis unveiled the morphology and microstructure of the nano composites, revealing well-defined nanostructures with uniform distribution of Cd-Ni nanoparticles within the polyaniline matrix. This morphology suggests successful synthesis of the nano composites with the desired structural characteristics. X-ray Diffraction (XRD) patterns confirmed the crystalline nature and phase purity of the synthesized nano composites. The presence of characteristic peaks corresponding to the crystalline phases of Cd-Ni and polyaniline indicated the absence of impurities and undesired phases[\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. These results underscored the high purity and crystallinity of the synthesized nano composites, laying a solid foundation for their potential application in gas sensing. Gas sensing experiments were conducted using Arduino software 1.8.16 to evaluate the sensing performance of the synthesized nano composites towards NH₃ gas. Different concentrations of NH₃ gas (5 ppm, 10 ppm, 15 ppm) were introduced into the testing environment. Among the tested compositions, the nano composite with 10% Cd doping in NiO exhibited the most promising sensing results. Analyzing the data involves comparing the measured gas concentrations with the known concentrations introduced during the experiment. Factors such as sensor drift, environmental conditions (e.g., temperature, humidity), and cross-sensitivity to other gases should be considered during data interpretation. Adjustments to the calibration curve or sensor calibration parameters may be necessary to optimize sensor performance and minimize measurement errors[\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe uniform response and recovery times across different concentrations highlight the sensor's capability for rapid detection and reset, which is crucial for real-time monitoring applications. Rapid response times ensure that the sensor can quickly detect the presence of NH\u003csub\u003e3\u003c/sub\u003e, while fast recovery times allow the sensor to be ready for subsequent measurements without significant delays. These characteristics are essential for applications where continuous monitoring is required. The combination of cadmium-doped NiO and PANI in the composite material enhances the NH\u003csub\u003e3\u003c/sub\u003e sensing capabilities. NiO, known for its semiconducting properties, provides a stable matrix for electron transport, while PANI, a conducting polymer, enhances the composite's overall conductivity. The doping with cadmium likely improves the material's electronic properties, increasing its sensitivity to gas interactions. This synergistic effect between NiO and PANI results in a composite material that is highly responsive to NH\u003csub\u003e3\u003c/sub\u003e. In addition to its high sensitivity, the composite material exhibits a clear and measurable response to varying NH\u003csub\u003e3\u003c/sub\u003e concentrations[\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. This characteristic is critical for practical applications, as it allows for the precise quantification of NH\u003csub\u003e3\u003c/sub\u003e levels in the environment. The ability to detect and measure different concentrations of NH\u003csub\u003e3\u003c/sub\u003e accurately makes the composite material suitable for a wide range of applications, from industrial safety monitoring to environmental protection. The consistent increase in resistance with increasing NH\u003csub\u003e3\u003c/sub\u003e concentration indicates that the sensor's response is primarily due to the interaction between NH\u003csub\u003e3\u003c/sub\u003e molecules and the active sites on the composite material[\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. This interaction likely involves the adsorption of NH\u003csub\u003e3\u003c/sub\u003e molecules onto the surface of the composite, leading to changes in the material's resistance. The degree of adsorption, and consequently the resistance change, increases with higher NH\u003csub\u003e3\u003c/sub\u003e concentrations, resulting in the observed linear relationship. Further analysis of the composite material's properties could provide insights into the mechanisms underlying its high sensitivity and rapid response to NH\u003csub\u003e3\u003c/sub\u003e. Understanding these mechanisms could help in optimizing the material's formulation to enhance its performance further. For instance, varying the concentration of cadmium doping or adjusting the ratio of NiO to PANI could potentially improve the sensor's selectivity and sensitivity.\u003c/p\u003e \u003cp\u003eThe superior sensing performance of the 10% Cd-doped NiO nano composite can be attributed to the synergistic effects of Cd doping and the polyaniline matrix[\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. Cd doping modifies the electronic structure and surface properties of NiO, enhancing its sensitivity towards NH₃ gas molecules. Additionally, Cd doping promotes the formation of additional active sites for gas adsorption, thereby improving the overall gas sensing response. Furthermore, the presence of polyaniline as a matrix material further enhances the gas sensing properties of the nano composites. Polyaniline provides a conductive network for electron transport, facilitating rapid and efficient detection of NH₃ gas molecules. Moreover, the porous structure of polyaniline promotes gas diffusion and adsorption, leading to improved sensitivity and response time of the gas sensors.\u003c/p\u003e \u003cp\u003eThe optimal sensing performance achieved with the 10% Cd-doped NiO nano composite highlights its potential for real-world NH₃ gas detection applications, such as environmental monitoring and industrial safety[\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. The synthesized nano composites offer a cost-effective and reliable solution for sensitive and selective NH₃ gas detection. Future research may focus on further optimizing the synthesis parameters and exploring additional applications of these nano composites in gas sensing technologies.\u003c/p\u003e"},{"header":"4.0 Conclusion","content":"\u003cp\u003eThe development of cadmium-doped nickel nanocomposites combined with polyaniline (Cd-Ni/PANI) for ammonia (NH₃) gas sensing applications represents a significant advancement in sensor technology. This innovative approach leverages the unique properties of both the metal nanocomposites and the conducting polymer, resulting in a sensor that exhibits remarkable sensitivity, selectivity, and stability for detecting NH₃ gas at low concentrations. Cadmium doping enhances the electronic properties of nickel nanoparticles, which improves their interaction with NH₃ molecules. Meanwhile, polyaniline offers a high surface area for gas adsorption and efficient electron transport pathways. This combination produces a synergistic effect, optimizing the gas sensing capabilities of the sensor[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe enhanced performance of the Cd-Ni/PANI sensor is evident in its high sensitivity and selectivity. The sensor can detect very low concentrations of NH₃, making it ideal for applications that require precise detection. Its selectivity ensures minimal interference from other gases[\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e], which is crucial for reliable monitoring in complex environments. Additionally, the sensor exhibits rapid response and recovery times, allowing for real-time monitoring of NH₃ levels. This quick responsiveness is essential for applications where immediate detection and action are required to prevent hazards.\u003c/p\u003e \u003cp\u003eThe sensor's stability and repeatability further underscore its robustness and practicality for long-term use. The Cd-Ni/PANI sensor maintains consistent performance over multiple cycles of NH₃ exposure and removal, indicating its durability and reliability. This stability is particularly important for continuous monitoring applications in industrial and environmental settings, where sensor performance must remain consistent over extended periods. The sensor's ability to withstand repeated use without significant degradation makes it a valuable tool for ongoing monitoring tasks.\u003c/p\u003e \u003cp\u003eThe potential applications of the Cd-Ni/PANI sensor are broad and impactful. In environmental monitoring, the sensor can detect NH₃ emissions from industrial and agricultural sources, helping to ensure compliance with environmental regulations and protect public health. In industrial safety, the sensor can monitor NH₃ levels in chemical plants, refrigeration systems, and other settings where NH₃ is used or produced, thereby preventing hazardous leaks and ensuring a safe working environment. Looking to the future, several research directions and applications can be pursued to further enhance the performance and utility of the Cd-Ni/PANI sensor[\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. Optimizing the doping levels of cadmium, exploring advanced fabrication techniques like electrospinning or 3D printing, and developing miniaturized, portable sensors for continuous monitoring are promising avenues[\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]. Investigating other doping elements and conductive polymers could lead to even better sensor performance. Moreover, assessing the environmental and health impacts of using cadmium-doped materials and conducting a comprehensive cost analysis for commercial production will be essential for the sustainable application and market viability of these sensors. Overall, the development of Cd-Ni/PANI nanocomposite sensors marks a significant step forward in NH₃ gas sensing technology, offering a robust and efficient solution for a wide range of practical applications.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflict of interest:\u003c/h2\u003e \u003cp\u003eAuthors have no conflict of interest\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eDhivyadharshini N: work, synthesis of polymer composite and characterization, manuscript writingVarun D S : work, synthesis of polymer composite and characterization, manuscript writingS Dilip Kumar: work, synthesis of polymer composite and characterization, manuscript writingDr. Basavaraj R J: GuidanceDr.Vishnumurthy KA : work, synthesis of polymer composite and characterization, analysis, guidance, manuscript writing\u003c/p\u003e\u003ch2\u003eAcknowledgement:\u003c/h2\u003e \u003cp\u003eAuthors are grateful for RV College of Engineering for providing opportunity to carryout this research work.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eMimani T, Patil KC SOLUTION COMBUSTION SYNTHESIS OF NANOSCALE OXIDES AND THEIR COMPOSITES\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAruna ST, Mukasyan AS (2008) Combustion synthesis and nanomaterials, \u003cem\u003eCurr. 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J Alloys Compd 682:850\u0026ndash;855. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jallcom.2016.05.038\u003c/span\u003e\u003cspan address=\"10.1016/j.jallcom.2016.05.038\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Polymer nano composites, cadmium doped nanoparticles, ammonia sensing","lastPublishedDoi":"10.21203/rs.3.rs-4514715/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4514715/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eSynthesis and characterization of cadmium-doped nickel (Cd-Ni) nanocomposites integrated with polyaniline (PANI) for advanced ammonia (NH₃) gas sensing applications. The Cd-Ni nanocomposites were synthesized via a solution combustion synthesis (SCS) method, providing a facile and efficient route to obtain homogeneous materials. The composites were further incorporated with PANI to enhance their gas sensing properties. Structural, morphological, and compositional properties were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Gas sensing performance was evaluated at various NH₃ concentrations and operating temperatures. The Cd-Ni/PANI sensors demonstrated significantly enhanced sensitivity, selectivity, and rapid response/recovery times compared to undoped NiO and Cd-Ni sensors. The improved gas sensing characteristics are attributed to the synergistic effects of cadmium doping and the conductive polymer matrix, which introduces additional active sites and modifies the electronic properties of the nanocomposite. These findings suggest that Cd-Ni/PANI composites are promising candidates for efficient and reliable NH₃ gas sensors, potentially advancing applications in environmental monitoring and industrial safety.\u003c/p\u003e","manuscriptTitle":"Development of Cadmium doped Nickel polymer nano composites for enhanced NH₃ gas sensing applications","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-06-20 16:15:10","doi":"10.21203/rs.3.rs-4514715/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"f4dd3b4e-8f6b-480b-b53d-b12ce995d84a","owner":[],"postedDate":"June 20th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-06-27T07:38:22+00:00","versionOfRecord":[],"versionCreatedAt":"2024-06-20 16:15:10","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4514715","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4514715","identity":"rs-4514715","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}