Investigating the Physicochemical and Optical Properties of PANI and PANI-ZnO Thin Films for an Efficient Ammonia Sensor at Ambient Conditions

Investigating the Physicochemical and Optical Properties of PANI and PANI-ZnO Thin Films for an Efficient Ammonia Sensor at Ambient Conditions | 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 Investigating the Physicochemical and Optical Properties of PANI and PANI-ZnO Thin Films for an Efficient Ammonia Sensor at Ambient Conditions Shilpa P. Dhanve, Yashavant Gutte, Chandrakant Birajdar This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4603844/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 Recently, owing to the versatile properties of conducting polymer-nanomaterial composite thin films have been extensively employed in diverse applications. Within this framework, the present investigation reported the NH 3 gas sensing ability of zinc oxide nanoparticles doped polyaniline (PANI-ZnO) composite thin films along with physicochemical and optoelectronic properties. The PANI-ZnO nanocomposite thin films were harvested using a soft chemical polymerisation technique over a glass substrate. The physicochemical and optoelectronic properties of the developed thin films were explored using the XRD, FESEM, UV-Vis. and FTIR characterisation techniques. The NH 3 gas sensing properties of PANI and PANI-ZnO nanocomposite thin film at ambient temperature were studied using the chemiresistive sensing technique. The developed PANI-ZnO sensor exhibited an excellent response toward the target NH 3 gas with outstanding sensitivity, selectivity, linearity, and stability. Comparatively, the PANI-ZnO thin films show enhanced sensitivity, stability, response and recovery time than the PANI film. Thus, the present study declared that the developed PANI-ZnO thin films are promising candidates for low-concentration detection of NH 3 gas with appropriate response and recovery time. Conducting Polymer Nanocomposite Thin Films Polyaniline-Zinc oxide Physicochemical Properties Ammonia sensor Figures Figure 1 Figure 2 Figure 4 Figure 5 Figure 6 1. Introduction Technological development has enriched human life and made it more comfortable and convenient. However, the industries established to produce various devices and products have negatively impacted the environment. Industrial production outsources multiple types of pollutants mainly air pollutants that harm humans as well as the environment. In general, gases such as ammonia (NH 3 ), hydrogen sulphide (H 2 S), carbon monoxide (CO), nitrogen dioxide (NO 2 ), sulphur dioxide (SO 2 ), carbon dioxide (CO 2 ), and nitric oxide (NO), etc. are considered the most harmful gases which released from various processes [ 1 , 2 ]. Ammonia (NH3) is a hazardous gas that is commonly found in the atmosphere as a result of chemical processes, fertilizer use, material processing, refrigeration, and other sources [ 3 , 4 ]. Exposure to ammonia can have various adverse effects on the human body, including damage to the respiratory and cardiac systems, as well as the skin and eyes [ 5 ]. Therefore, to protect from these pollutants their quantitative detection with time being is the utmost necessity for precaution [ 6 ]. Worldwide various research groups have been working to develop a sophisticated and affordable gadget for widespread use by large-scale users for detection of gases [ 7 ]. A gas sensor is an analytical device that promises to detect harsh pollutant gases qualitatively and quantitatively [ 8 ]. The ability of sensors to operate at room temperature (RT) is highly desirable, as it is crucial for detecting harmful gases in the surrounding air [ 9 ]. In real-world scenarios, these sensors play a vital role in detecting and tracking harmful gases, making real-time operation essential for practical applications [ 10 ]. Therefore, in the realm of scientific research and technological advancement, it is imperative to develop gas sensors that meet these rigorous standards [ 11 ]. The selection of materials with desired properties is crucial when fabricating gas sensors for practical applications. Several criteria decide the choice of gas sensing material, including operating environment, sensitivity, target gas, cost, etc. Recently, a variety of materials have been utilized in the development of gas sensors including metal oxides, conducting polymers, carbon materials, and more. Among these, conducting polymers are widely used in gas sensors due to their unique physicochemical properties which enhance the sensing parameters such as high sensitivity, selectivity, stability, detection limit as well as operation at room temperature, etc. The family of conducting polymers enriched with the candidates including polyaniline (PANI), polypyrrole (PPY), polythiophene (PTh), etc. Particularly, in gas sensing applications PANI is used extensively due to its excellent properties i.e. tuneable electrical conductivity, redox property, larger surface area, high flexibility, outstanding stability at ambient conditions, cost-effectiveness, and ease of fabrication, etc. However, PANI suffers from low mechanical strength, which adversely affects its sensitivity and specific selectivity [ 12 – 14 ]. The major issue associated with PANI use in gas sensors can be resolved by doping with various organic and inorganic materials. The proper doping enhances the mechanical strength of PANI and creates more active sites by altering its structure [ 15 , 16 ]. Integrating inorganic nanoparticles into PANI can dramatically enhance the sensitivity, selectivity, and overall performance of gas sensors. The synergistic effect of inorganic nanoparticles and PANI increases surface area and tuned electrical conductivity, improves catalytic activity, stability, durability, and enhances the charge transfer ability [ 17 , 18 ]. Recently, zinc oxide (ZnO), titanium dioxide (TiO₂), and iron oxide (Fe₂O₃) as inorganic nanoparticles were incorporated into PANI to detect NH 3 [ 19 , 20 ]. ZnO is a highly intriguing option for gas sensing applications because of its unique properties including a wide direct band gap, high exciton binding energy, biocompatibility, non-toxicity, high chemical stability, strong electron transfer capability, and exceptional mechanical strength [ 21 , 22 ] However, ZnO-based gas sensors have trouble operating at room temperature [ 23 ]. Thus, the PANI-ZnO nanocomposite has paved the way to enhance gas sensor parameters even at room temperature. Recently, Kaur, R. et.al. reported the PANI-ZnO nanocomposite with varying concentrations of ZnO nanoparticles for ammonia detection. The developed sensor shows a response of 1.43–25.24% for 5–200 ppm with 5 ppm as the lower limit of detection and 18 s as the response time at the temperature range 20–100°C [ 24 ]. In another study, Bai, Y. presented a ZnO/PANI film prepared by spraying ZnO nanorods synthesized using the hydrothermal method to detect NH 3 at room temperature. The film detected concentrations of 0.1–100 ppm of NH 3 , with the response value doubling to 12.96 for 100 ppm NH 3 and the recovery time shortening to 31.2 seconds, which is 1/5 of the original time [ 25 ]. The research conducted by Karmakar, N. involved developing nanocomposite polyaniline (PANI) films with varying concentrations of ZnO and studying their ability to detect ammonia gas. They found that loading 10 at% ZnO in PANI resulted in a gas sensing response of 59% for 120 ppm NH 3 gas. Additionally, they embedded Ag-decorated ZnO nanorods in the PANI matrix using the in-situ oxidative polymerization technique, which showed a response of 70% at 120 ppm and a recovery time of less than 120 s [ 26 ]. Here, we have presented PANI-ZnO nanocomposite films with varying concentrations of ZnO for NH 3 detection. The physicochemical and optical properties of PANI and PANI-ZnO thin films were explored, along with NH 3 detection. The study demonstrated that the sensing parameters of the PANI-based sensor can be improved by doping ZnO nanoparticles significantly 2. Experimental 2.1 Materials and Characterization Techniques In this investigation, all analytical reagent grade (AR grade) chemicals were used without further purification, except for aniline. Aniline, ammonium persulphate, sulfuric acid (H 2 SO 4 ), acetone, zinc chloride, and sodium hydroxide pellets were sourced from Loba Chem, India. All reactions were carried out using double distilled water obtained from a laboratory distillation apparatus. The PANI and PANI-ZnO thin films were characterized using an X-ray diffractometer (XRD) (Mini Flex II, Rigaku, Japan) with CuKα radiation of wavelength 1.5406 Å and scanning electron microscope (SEM) technique using ZEISS (Gemini SEM 360) from Germany for structural and morphological characterization respectively. The UV–Vis. spectrum was recorded using a UV–Vis. fibre-optic spectrophotometer (BLAC-SR, Stellar Net, USA), and functional groups were studied via FTIR spectroscopy using an α-ATR IR-spectrophotometer (Bruker, Japan). All sensor parameters were analysed using a Keithley 6514 electrometer with a data acquisition system controlled by a computer. 2.2 Synthesis of ZnO nanoparticles The ZnO nanoparticles were synthesized using the chemical co-precipitation method. First, 0.1 M of Zinc chloride was mixed in 50 ml of DI water using a magnetic stirrer for 30 minutes. In a separate beaker, 0.2 M of sodium hydroxide (NaOH) pellets were dissolved in 50 ml of DI water. The NaOH solution was then added drop by drop into the ZnCl 2 solution over 30 minutes with constant stirring, resulting in the formation of white precipitation. The mixture was left to stir constantly for 2 hours. The obtained precipitation was then filtered using Whatman filter paper and dried at room temperature for 12 hours. The dried material was processed into a fine powder and calcinated at 300°C for 2 hours. 2.3 Preparation of PANI and PANI-ZnO thin films The PANI and PANI-ZnO thin films were prepared using a soft chemical method. Figure (1a) illustrates the experimental procedure. To start, equal concentrations (0.1M) of aniline and ammonium persulphate (APS) were mixed with 1M of H 2 SO 4 in 50 ml of distilled water. Prior to the polymerization process, both solutions were cooled for 1 hour to maintain a temperature of approximately 4°C. The aniline solution was stirred by immersing a glass substrate, and the APS solution was added dropwise to it. The dark green PANI film began to deposit over the glass substrate after 15 minutes. The films were removed from the solution after 2 hours, washed with acetone and DI water four times, and then dried at room temperature. The deposition of PANI-ZnO thin films over the substrate same procedure was adopted with slight modification. In the process of forming PANI-ZnO thin films, different concentrations of ZnO nanoparticles (10%, 20%, 30%) were dispersed in an aniline solution using ultrasonication in three separate beakers before the polymerization process. Thereafter, we followed the same procedure as the one used for forming the PANI film. 3. Results and discussion 3.1 Material characterization 3.1.1 Structural Properties (X-ray diffraction analysis) XRD characterization techniques were used to investigate the structural properties of the developed PANI, PANI-ZnO thin films, and ZnO nanoparticles. Figure (2a) depicts the typical XRD patterns of synthesized ZnO nanoparticles, showing the expected diffraction peaks that match well with the ICPDS card. 96-900-4180. ICD. The diffraction peaks observed at 2θ = 31.73°, 34.42°, 36.22°, 47.51°, 56.53°, 62.83°, 66.30°, 67.89°, 69.05°, 72.56°, 76.89°, and 67.98° in all diffraction patterns correspond to the (100), (002), (101), (102), (110), (103), (200), (112), (201), (004), and (202) planes for the hexagonal wurtzite phase of ZnO in its polycrystalline form [ 27 , 28 ]. XRD patterns of PANI and PANI-ZnO (10–30 wt.%) thin films are illustrated in Fig. (2b). PANI exhibits two broad diffraction peaks at approximately 2θ = 19.92 O and 25.51 O , which are typically attributed to the (110) and (200) planes, respectively. The broad peaks observed indicate that PANI is amorphous with some degree of crystallinity [ 29 ]. XRD patterns of PANI-ZnO (10, 20, 30 wt.%) composites show higher crystallinity compared to PANI as the concentration of ZnO increases [ 30 ]. At the highest concentration of 30 wt.%, the diffraction pattern showed more peaks like ZnO, and the peaks shifted towards the lower angle side [ 31 ]. 3.1.2 Morphological Study of PANI and PANI-ZnO Thin Films Figure (3 a-h) depict the surface morphology of the developed PANI and PANI-ZnO thin films. Figure (3 a-d) display the FESEM images of the PANI and PANI-ZnO thin films at a lower resolution. At this lower resolution, the surface of all films showed good dispersion of materials over the thin films. The pure PANI shows a smooth surface over the substrate, whereas the PANI-ZnO thin films exhibited an uneven, rough surface. Figure 1 e shows the microscopic view of pure PANI, revealing an agglomerated porous structure. Figure (3 f-h) visualize the surface morphology of the PANI-ZnO thin films of different concentrations of ZnO (10–30 wt.%) at higher resolution. At higher resolution microscopic study reveals that the PANI morphology in amorphous agglomerated structure and the PANI-ZnO (10, 20, 30 wt.%) shows the amorphous nature with dispersion of ZnO nanoparticles. It demonstrates the uniform distribution of ZnO, while also showing a highly porous natured surface. 3.1.3 Functional group study (FTIR) FTIR spectrum of the developed PANI and PANI-ZnO thin films exhibited the expected peaks with the characteristic peaks, shown in Fig. 4 . The peaks originated at 597 and 696 cm⁻¹ in substituted benzenes due to the out-of-plane bending vibrations of C-H bonds in aromatic rings [ 32 , 33 ]. The 786 and 867 cm⁻¹ peaks are preferably attributed to out-of-plane bending vibrations of C-H bonds in 1,2,4-trisubstituted benzene rings and aromatic C-H bonds respectively [ 34 ]. The peak at 1046 cm⁻¹ is typically associated with in-plane bending vibrations of C-H bonds in aromatic rings [ 35 ]. In PANI, C-N stretching vibrations in the benzenoid units are observed at 1244 cm⁻¹, and the 1298 cm⁻¹ peak is linked to C-N stretching in the quinoid units [ 36 ]. Additionally, the benzenoid units show C = C stretching vibrations at 1469 cm⁻¹, with the 1519 cm⁻¹ peak indicating C = C stretching in the quinoid units [ 37 ]. In PANI-ZnO nanocomposites, the peaks exhibit slight shifts to higher wavenumbers due to the ZnO nanoparticles within the PANI matrix [ 38 ]. The 570 cm⁻¹ peak, characteristic of Zn-O stretching vibrations, indicates the presence of ZnO [ 39 ]. The 3859 cm⁻¹ peak relates to O-H stretching vibrations, likely from hydroxyl groups on ZnO, while the 3903 cm⁻¹ peak may indicate lattice vibrations in ZnO or interactions between PANI and ZnO at the interface [ 40 ]. Thus, the FTIR study confirms the existence and interaction of ZnO nanoparticles in the PANI matrix [ 41 ]. 3.1.4 UV-Vis Spectroscopy The optical properties of the developed PANI and PANI-ZnO thin films were analyzed using UV-Vis. absorption spectroscopy. Figure (5 a) shows the UV-Vis. absorption spectrum of PANI and PANI (10, 20, 30 wt.%) thin films. Both pure PANI and ZnO nanoparticles incorporated PANI thin films showed two absorption peaks. The pure PANI displayed peaks at wavelengths of 341 nm and 606 nm. The 341 nm peak is associated with the π-π* transition of the benzenoid rings in the polyaniline chain, representing the electronic transition from the HOMO to LUMO in the benzenoid units [ 42 ]. The second peak at 606 nm is attributed to polaron transitions in polyaniline, which are charge carriers in the polymer [ 43 ]. In the case of PANI-ZnO thin films, the observed peaks in pure PANI shifted slightly with increasing concentration of ZnO nanoparticles. The shifting of the absorption bands may be due to interactions between PANI and ZnO nanoparticles [ 44 ]. The bandgaps of the developed films were calculated by analyzing the UV–Vis. spectra using Tauc's relation as shown in Eq. 1 [ 45 ]. $$\alpha h\nu =A {(h\nu -{E}_{g})}^{2}------------\left(1\right)$$ where, A is a constant, h is Planck’s constant, Eg is the optical band gap, hν is photon energy, and α is the absorption coefficient for the direct band gap. Figure (5 b) shows the Tauc plot, and bandgaps are shown as 3 eV for PANI, and 2.75, 2.71, and 2.58 eV for PANI-ZnO (at 10%, 20%, and 30% wt.%) respectively. The study of bandgap indicates that as the concentration of ZnO nanoparticles increases, the bandgap of PANI decreases. 4. Sensor Performance 4.1.1 Sensitivity and Detection Limit The sensitivity of the developed gas sensors merely depends upon the physicochemical and optoelectrical properties of used materials. Sensing parameters of the developed PANI and PANI-ZnO thin films were examined for different concentrations of NH 3 gas by chemiresistive modality. In this investigation, lower concentrations (5–50 ppm) shown in Fig. (6 a) and higher concentrations (100–500 ppm) Fig. (6 b) of NH 3 were studied to analyse the sensor parameters. The sensitivity of the developed sensors was examined by the change in resistance with respect to time with exposure and removal of various concentrations of NH 3 . The sensitivity of the sensor is defined as: $$S \left(\%\right)=\frac{({R}_{target gas}-{R}_{air})}{{R}_{air}}\times 100 -------\left(2\right)$$ Where R target gas and R air represent the resistances of the sensor film in the presence of target gas and air, respectively. At room temperature for concentrations of 10–50 ppm and it exhibited the rapid change in resistance and then reached saturation. The change in the resistance by exposing NH 3 occurs due to the removal of free electrons from the conduction band of the composite by the adsorbed oxygen species which act as trapped states. The developed sensor elements show an excellent response towards the NH 3 with high selectivity. Compared to the PANI-based sensor, the PANI-ZnO sensor increases the sensing response by 9-fold and it enhances more when the ZnO concentration in PANI. The linearity of the response was demonstrated by linear fitting (Fig. 6 c) and it shows the R 2 value of 0.997, it confirmed the excellence of the developed sensors. The lower detection limit for the developed thin film-based sensor is 5 ppm, as the measurable response is shown for this concentration. 4.1.2 Selectivity The selectivity of the developed PANI-ZnO thin film-based sensor was tested by exposing the different interference species such as methanol, carbon dioxide, ethanol, and nitrogen dioxide. Figure (6 d) shows the selective response of the PANI-ZnO (30%) film to NH 3 compared to the mentioned species for a 400 ppm concentration at room temperature. The PANI-ZnO thin film exhibited the highest response compared to the negligible response of the other checked interference species. This indicates that the PANI-ZnO nanocomposite-based sensor has the promising capability to detect NH 3 gas with very high selectivity. 4.1.3 Response Time, Recovery Time, and Stability The response and recovery time of the developed sensor confirms its usefulness in practical applications. The response and recovery time were measured by recording the time it took for the sensor's response to reach 90% of its saturation value (Rg) when exposed to the gas, as well as the time it took for the sensor to drop to 10% of its initial value (Ra) when the gas was removed. For the PANI-based sensor, the response time shown as ~ 70 seconds, and the recovery time is ~ 100 seconds for 100 ppm NH 3 gas. However, the response and recovery times decrease significantly for all PANI-ZnO thin films compared to PANI film. For PANI-ZnO (30%), the response time is approximately 45 seconds, and the recovery time is approximately 70 seconds. The stability of the developed thin films towards NH 3 was measured for 45 days, with a change in response measured every 5 days as shown in Fig. (6 e). The PANI film demonstrates 69% stability, while PANI-ZnO (30%) shows a 96% stable response during the measured period. Thus, the study exhibited that PANI-based sensors can enhance stability by doping the ZnO nanoparticles. 5. Conclusion In the current study, we have successfully developed PANI and PANI-ZnO thin films using a soft chemical method. We have analysed the structural, morphological and optical properties of the thin films using techniques such as XRD, FESEM, FTIR, and UV-Vis. spectroscopy etc. The developed thin films were employed to detect NH 3 using chemiresistive technique modality. We evaluated the performance of sensors by examining parameters such as sensitivity, reproducibility, selectivity, stability etc. The sensors exhibited excellent response to NH 3 concentrations ranging from 5–50 ppm as low concentrations and 100–500 ppm as high concentrations at room temperature. The lowest detection limit of the thin films was found to be 5 ppm, and they demonstrated superior selectivity when tested against various interfering substances. In summary, PANI-based sensors can effectively detect NH 3 gas at ambient temperature, and the sensing capabilities of these sensors were significantly improved by doping ZnO nanoparticles. Declarations Conflict of Interest The authors declared no conflict of Interest. Author Contribution Author contributionsSPD: Experimental work, data analysis and drafting ofmanuscript, YPG: Data analysis, drafting of the manuscript,CTB : Planning of experiments, draftingand editing of the manuscript. Acknowledgement SPD : gratefully acknowledges to the UGC for National fellowship for doctor of philosophy as financial assistance References Ganguly, T., Selvaraj, K. L., & Guttikunda, S. K. (2020). National Clean Air Programme (NCAP) for Indian cities: Review and outlook of clean air action plans. Atmospheric Environment: X, 8, 100096. Wang, Z., Hua, P., Li, R., Bai, Y., Fan, G., Wang, P., … Krebs, P. (2019). Concentration decline in response to source shift of trace metals in Elbe River, Germany: a long-term trend analysis during 1998–2016. Environmental pollution, 250, 511–519. Sapek, A. (2013). Ammonia emissions from non-agricultural sources. Polish Journal of Environmental Studies, 22(1). Dadhich, J. P., Smith, J. P., Iellamo, A., & Suleiman, A. (2021). Climate change and infant nutrition: estimates of greenhouse gas emissions from milk formula sold in selected Asia Pacific countries. Journal of Human Lactation, 37(2), 314–322. Klaassen, C. D., & Amdur, M. O. (Eds.). (2013). Casarett and Doull's toxicology: the basic science of poisons (Vol. 1236, pp. 189–190). New York: McGraw-Hill. Brintlinger, T., Herzing, A. A., Long, J. P., Vurgaftman, I., Stroud, R., & Simpkins, B. S. (2015). Optical dark-field and electron energy loss imaging and spectroscopy of symmetry-forbidden modes in loaded nanogap antennas. ACS nano, 9(6), 6222–6232. Bag, A., & Lee, N. E. (2021). Recent advancements in development of wearable gas sensors. Advanced Materials Technologies, 6(3), 2000883. Bousiotis, D., Alconcel, L. N. S., Beddows, D. C., Harrison, R. M., & Pope, F. D. (2023). Monitoring and apportioning sources of indoor air quality using low-cost particulate matter sensors. Environment International, 174, 107907. Wang, Z., Zhu, L., Sun, S., Wang, J., & Yan, W. (2021). One-dimensional nanomaterials in resistive gas sensor: From material design to application. Chemosensors, 9(8), 198. Xiao, Y., Li, H., Wang, C., Pan, S., He, J., Liu, A., … Lu, G. (2024). Room temperature wearable gas sensors for fabrication and applications. Advanced Sensor Research, 3(3), 2300035. Chen, J., Rong, F., & Xie, Y. (2023). Fabrication, Microstructures and Sensor Applications of Highly Ordered Electrospun Nanofibers: A Review. Materials, 16(9), 3310. Singh, E., Meyyappan, M., & Nalwa, H. S. (2017). Flexible graphene-based wearable gas and chemical sensors. ACS applied materials & interfaces, 9(40), 34544–34586. Que, H., Yan, X., Guo, B., Ma, H., Wang, T., Liu, P., … Yan, Y. (2019). Terminal deoxynucleotidyl transferase and rolling circle amplification induced G-triplex formation: A label-free fluorescent strategy for DNA methyltransferase activity assay. Sensors and Actuators B: Chemical, 291, 394–400. Namsheer, K., & Rout, C. S. (2021). Conducting polymers: a comprehensive review on recent advances in synthesis, properties and applications. RSC advances, 11(10), 5659–5697. Rajput, V. S., & Bhinder, J. (Eds.). (2023). Advanced Materials for Biomedical Applications: Development and Processing. Springer Nature. Singh, P., & Shukla, S. K. (2020). Advances in polyaniline-based nanocomposites. Journal of materials science, 55(4), 1331–1365. Lawaniya, S. D., Kumar, S., Yu, Y., Mishra, Y. K., & Awasthi, K. (2024). Metal oxide-polymer composites for gas-sensing applications. In Complex and Composite Metal Oxides for Gas VOC and Humidity Sensors Volume 1 (pp. 107–150). Elsevier. Xia, Y., Li, R., Chen, R., Wang, J., & Xiang, L. (2018). 3D architectured graphene/metal oxide hybrids for gas sensors: A review. Sensors, 18(5), 1456. Shakeel, A., Rizwan, K., Farooq, U., Iqbal, S., & Altaf, A. A. (2022). Advanced polymeric/inorganic nanohybrids: An integrated platform for gas sensing applications. Chemosphere, 294, 133772. Jadoun, S., Yáñez, J., Mansilla, H. D., Riaz, U., & Chauhan, N. P. S. (2022). Conducting polymers/zinc oxide-based photocatalysts for environmental remediation: a review. Environmental chemistry letters, 20(3), 2063–2083. Eriksson, J., Khranovskyy, V., Söderlind, F., Käll, P. O., Yakimova, R., & Spetz, A. L. (2009). ZnO nanoparticles or ZnO films: A comparison of the gas sensing capabilities. Sensors and Actuators B: Chemical, 137(1), 94–102. Allameh, P. (2014). Photocurrent Enhancement of Hematite Nanowires by Gold Underlayer Deposition and Ti Doping (Doctoral dissertation, UC San Diego). Bhati, V. S., Hojamberdiev, M., & Kumar, M. (2020). Enhanced sensing performance of ZnO nanostructures-based gas sensors: A review. Energy Reports, 6, 46–62. Kaur, R., Lawaniya, S. D., Kumar, S., Saini, N., & Awasthi, K. (2023). Nanoarchitectonics of polyaniline–zinc oxide (PANI–ZnO) nanocomposite for enhanced room temperature ammonia sensing. Applied Physics A, 129(11), 765. Bai, Y. Dong, X., Guo, C., Xu, Y., Wang, B., & Cheng, X. (2022). Spray synthesis of rapid recovery ZnO/polyaniline film ammonia sensor at room temperature. Frontiers of Materials Science, 16(4), 220620. Karmakar, N., Jain, S., Fernandes, R., Shah, A., Patil, U., Shimpi, N., & Kothari, D. (2023). Enhanced sensing performance of an ammonia gas sensor based on Ag-decorated ZnO nanorods/polyaniline nanocomposite. ChemistrySelect, 8(18), e202204284. Paul, S., & Ban, D. K. (2014). Synthesis, characterization and the application of ZnO nanoparticles in biotechnology. Int. J. Adv. Chem. Eng. Biol. Sci, 1(1), 1–5. Pardeshi, S. K., & Patil, A. B. (2009). Effect of morphology and crystallite size on solar photocatalytic activity of zinc oxide synthesized by solution free mechanochemical method. Journal of Molecular Catalysis A: Chemical, 308(1–2), 32–40. Li, D., Huang, J., & Kaner, R. B. (2009). Polyaniline nanofibers: a unique polymer nanostructure for versatile applications. Accounts of chemical research, 42(1), 135–145. Zhu, J., Shao, C., Li, X., Han, C., Yang, S., Ma, J., … Liu, Y. (2018). Immobilization of ZnO/polyaniline heterojunction on electrospun polyacrylonitrile nanofibers and enhanced photocatalytic activity. Materials Chemistry and Physics, 214, 507–515. Shah, M., Khan, N., Imran, Z., Khan, M., Khattak, A., Khan, A., & Ullah, N. (2019). Structural, optical and impedance spectroscopy study of thin film of polyaniline (PANI/ZnO) nanocomposite. Materials Research Express, 7(1), 015314. Giripunje, S. M., & Ghushe, J. (2013). Nanocomposite of polyaniline and ZnO: Preparation, characterisation, optical and electrical properties. Journal of Nano Research, 24, 123–132. Alamgeer, Tahir, M., Sarker, M. R., Ali, S., Ibraheem, Hussian, S., … Mohd Said, S. (2023). Polyaniline/ZnO Hybrid Nanocomposite: Morphology, Spectroscopy and Optimization of ZnO Concentration for Photovoltaic Applications. Polymers, 15(2), 363. Andreas, R., Lesbani, A., & Yusuf, F. A. (2019, April). The characteristics (compositions, morphological, and structure) of nanocomposites polyaniline (PANI)/ZnO. In IOP Conference Series: Materials Science and Engineering (Vol. 509, No. 1, p. 012126). IOP Publishing. Workman Jr, J. J. (1996). Interpretive spectroscopy for near infrared. Applied Spectroscopy Reviews, 31(3), 251–320. Quillard, S., Louarn, G., Lefrant, S., & MacDiarmid, A. G. (1994). Vibrational analysis of polyaniline: A comparative study of leucoemeraldine, emeraldine, and pernigraniline bases. Physical Review B, 50(17), 12496. Ibrahim, K. A. (2017). Synthesis and characterization of polyaniline and poly (aniline-co-o-nitroaniline) using vibrational spectroscopy. Arabian Journal of Chemistry, 10, S2668-S2674. Patil, S. L., Pawar, S. G., Chougule, M. A., Raut, B. T., Godse, P. R., Sen, S., & Patil, V. B. (2012). Structural, morphological, optical, and electrical properties of PANi-ZnO nanocomposites. International Journal of Polymeric Materials, 61(11), 809–820. Noei, H., Qiu, H., Wang, Y., Löffler, E., Wöll, C., & Muhler, M. (2008). The identification of hydroxyl groups on ZnO nanoparticles by infrared spectroscopy. Physical Chemistry Chemical Physics, 10(47), 7092–7097. Ghanbari, K., & Moloudi, M. (2016). Flower-like ZnO decorated polyaniline/reduced graphene oxide nanocomposites for simultaneous determination of dopamine and uric acid. Analytical biochemistry, 512, 91–102. Wang, Y., Hu, J., & Guo, Q. (2019). FTIR and lattice vibrations in ZnO nanoparticles within PANI matrix. Materials Letters, 237(1), 209–213. Ramya, K., & Subramaniam, K. (2020). Optical Properties of Polyaniline Thin Films. Journal of Materials Science, 55(5), 2567–2578. Singh, P., Kaur, G., & Sharma, V. (2021). UV-Vis Spectroscopic Analysis of Conducting Polymers. Spectroscopy Letters, 54(3), 156–165. Jain, R., Kothari, A., & Malhotra, B. (2019). Interaction Mechanism of PANI-ZnO Nanocomposites. Nanotechnology Reviews, 8(2), 234–243. Kumar, S., Verma, A., & Sharma, S. (2018). Bandgap Analysis of ZnO Nanoparticles. Applied Nanoscience, 8(6), 1215–1222. 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-4603844","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":324460887,"identity":"e528b3a3-fa33-474a-9b43-0f208407d2de","order_by":0,"name":"Shilpa P. Dhanve","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABA0lEQVRIie3PMUvDQBTA8TsOnAxd0ylfIcWxH8XFo5BMJwWXDLG8IsSlOJ9U0q/QLpkTHpxLwPXADhW/gCBIBhEvGYoIya2C9x8ed/B+cEeIy/UX8+myJIRddJe3xAzGwEbgSKisW0JthJAjYV7WyWESrG8A5+n0crReTQ5efn0+ujWkSYpeEu4rQKniK39fn4Xj4lFIpEBX9XM/8Tng6Qly0FHkTwolwBBGs34SyJZ8Id/oKG74gxIbGyHaEC9DvtUzRSpIxdZGwpbc38V8p2c4BlWKnSHV0F8CGb+8zj+mPNd8+f6ZLkT+hNWhSQYeZmI/ztjNcnD/F1nYll0ul+sf9g07cGf2k57SdwAAAABJRU5ErkJggg==","orcid":"","institution":"Dr. Babasaheb Ambedkar Marathwada University","correspondingAuthor":true,"prefix":"","firstName":"Shilpa","middleName":"P.","lastName":"Dhanve","suffix":""},{"id":324460888,"identity":"3e2394a1-519b-452f-a2e4-a8a368e45c8d","order_by":1,"name":"Yashavant Gutte","email":"","orcid":"","institution":"Dr. Babasaheb Ambedkar Marathwada University","correspondingAuthor":false,"prefix":"","firstName":"Yashavant","middleName":"","lastName":"Gutte","suffix":""},{"id":324460889,"identity":"02a11c9b-4bcc-4dd4-91ab-b7fc4f6d1c1a","order_by":2,"name":"Chandrakant Birajdar","email":"","orcid":"","institution":"Dr. Babasaheb Ambedkar Marathwada University","correspondingAuthor":false,"prefix":"","firstName":"Chandrakant","middleName":"","lastName":"Birajdar","suffix":""}],"badges":[],"createdAt":"2024-06-19 07:06:04","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4603844/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4603844/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":60645663,"identity":"7cd252e3-ba39-47ed-9e1e-98b4747decaa","added_by":"auto","created_at":"2024-07-19 04:51:43","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":396810,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a) Experimental scheme for the development of PANI-ZnO thin films, (b) sensing experiment\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4603844/v1/7069026da5e03af2de9a5f52.jpg"},{"id":60645081,"identity":"0151f27a-18dc-4d1c-97f6-b7b284d8b2e7","added_by":"auto","created_at":"2024-07-19 04:43:43","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":296968,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eXRD patterns of (a) ZnO nanoparticles, (b) PANI and PANI-ZnO (10, 20, 30 Wt.%) thin films\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4603844/v1/7e4c3bd314c51afb06c80e29.jpg"},{"id":60645942,"identity":"1f9de31a-940a-4f19-b827-6cd1a888e2de","added_by":"auto","created_at":"2024-07-19 04:59:43","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":452039,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFTIR spectra of PANI and PANI-ZnO (10, 20, 30 Wt.%) thin films\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4603844/v1/ee2b0767cbb835a8b8212ab6.jpg"},{"id":60645660,"identity":"1b28c85b-b5cf-4840-b223-826469bf9377","added_by":"auto","created_at":"2024-07-19 04:51:43","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":503969,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a) UV-Vis. absorption spectrum PANI and PANI-ZnO (10, 20, 30 Wt.%) thin films, (b) optical bandgaps of PANI and PANI-ZnO (10, 20, 30 Wt.%) thin films\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4603844/v1/cc6dd68bcdec088b8adaeb96.jpg"},{"id":60645082,"identity":"eee3e7ec-2e0c-41ed-b36d-93a589938776","added_by":"auto","created_at":"2024-07-19 04:43:43","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":615753,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a) Sensitivity of the developed sensors for 5 ppm to 50 ppm, (b) Sensitivity of the developed sensors for 100 ppm to 500 ppm, (c) Experimental fitting (linearity) (d) Stability of the developed sensors, (e) Selectivity of the developed sensors\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4603844/v1/101a40dd592265ee00ad1ff7.jpg"},{"id":60736358,"identity":"d48dce06-323f-4fd9-9fb4-c7ce61a4c009","added_by":"auto","created_at":"2024-07-20 10:59:39","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2827327,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4603844/v1/88c05984-f987-4f7e-b1c0-6c7b98a2c68c.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eInvestigating the Physicochemical and Optical Properties of PANI and PANI-ZnO Thin Films for an Efficient Ammonia Sensor at Ambient Conditions\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eTechnological development has enriched human life and made it more comfortable and convenient. However, the industries established to produce various devices and products have negatively impacted the environment. Industrial production outsources multiple types of pollutants mainly air pollutants that harm humans as well as the environment. In general, gases such as ammonia (NH\u003csub\u003e3\u003c/sub\u003e), hydrogen sulphide (H\u003csub\u003e2\u003c/sub\u003eS), carbon monoxide (CO), nitrogen dioxide (NO\u003csub\u003e2\u003c/sub\u003e), sulphur dioxide (SO\u003csub\u003e2\u003c/sub\u003e), carbon dioxide (CO\u003csub\u003e2\u003c/sub\u003e), and nitric oxide (NO), etc. are considered the most harmful gases which released from various processes [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Ammonia (NH3) is a hazardous gas that is commonly found in the atmosphere as a result of chemical processes, fertilizer use, material processing, refrigeration, and other sources [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Exposure to ammonia can have various adverse effects on the human body, including damage to the respiratory and cardiac systems, as well as the skin and eyes [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Therefore, to protect from these pollutants their quantitative detection with time being is the utmost necessity for precaution [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Worldwide various research groups have been working to develop a sophisticated and affordable gadget for widespread use by large-scale users for detection of gases [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. A gas sensor is an analytical device that promises to detect harsh pollutant gases qualitatively and quantitatively [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The ability of sensors to operate at room temperature (RT) is highly desirable, as it is crucial for detecting harmful gases in the surrounding air [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. In real-world scenarios, these sensors play a vital role in detecting and tracking harmful gases, making real-time operation essential for practical applications [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Therefore, in the realm of scientific research and technological advancement, it is imperative to develop gas sensors that meet these rigorous standards [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe selection of materials with desired properties is crucial when fabricating gas sensors for practical applications. Several criteria decide the choice of gas sensing material, including operating environment, sensitivity, target gas, cost, etc. Recently, a variety of materials have been utilized in the development of gas sensors including metal oxides, conducting polymers, carbon materials, and more. Among these, conducting polymers are widely used in gas sensors due to their unique physicochemical properties which enhance the sensing parameters such as high sensitivity, selectivity, stability, detection limit as well as operation at room temperature, etc. The family of conducting polymers enriched with the candidates including polyaniline (PANI), polypyrrole (PPY), polythiophene (PTh), etc. Particularly, in gas sensing applications PANI is used extensively due to its excellent properties i.e. tuneable electrical conductivity, redox property, larger surface area, high flexibility, outstanding stability at ambient conditions, cost-effectiveness, and ease of fabrication, etc. However, PANI suffers from low mechanical strength, which adversely affects its sensitivity and specific selectivity [\u003cspan additionalcitationids=\"CR13\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe major issue associated with PANI use in gas sensors can be resolved by doping with various organic and inorganic materials. The proper doping enhances the mechanical strength of PANI and creates more active sites by altering its structure [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Integrating inorganic nanoparticles into PANI can dramatically enhance the sensitivity, selectivity, and overall performance of gas sensors. The synergistic effect of inorganic nanoparticles and PANI increases surface area and tuned electrical conductivity, improves catalytic activity, stability, durability, and enhances the charge transfer ability [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Recently, zinc oxide (ZnO), titanium dioxide (TiO₂), and iron oxide (Fe₂O₃) as inorganic nanoparticles were incorporated into PANI to detect NH\u003csub\u003e3\u003c/sub\u003e [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. ZnO is a highly intriguing option for gas sensing applications because of its unique properties including a wide direct band gap, high exciton binding energy, biocompatibility, non-toxicity, high chemical stability, strong electron transfer capability, and exceptional mechanical strength [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] However, ZnO-based gas sensors have trouble operating at room temperature [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThus, the PANI-ZnO nanocomposite has paved the way to enhance gas sensor parameters even at room temperature. Recently, Kaur, R. et.al. reported the PANI-ZnO nanocomposite with varying concentrations of ZnO nanoparticles for ammonia detection. The developed sensor shows a response of 1.43\u0026ndash;25.24% for 5\u0026ndash;200 ppm with 5 ppm as the lower limit of detection and 18 s as the response time at the temperature range 20\u0026ndash;100\u0026deg;C [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. In another study, Bai, Y. presented a ZnO/PANI film prepared by spraying ZnO nanorods synthesized using the hydrothermal method to detect NH\u003csub\u003e3\u003c/sub\u003e at room temperature. The film detected concentrations of 0.1\u0026ndash;100 ppm of NH\u003csub\u003e3\u003c/sub\u003e, with the response value doubling to 12.96 for 100 ppm NH\u003csub\u003e3\u003c/sub\u003e and the recovery time shortening to 31.2 seconds, which is 1/5 of the original time [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The research conducted by Karmakar, N. involved developing nanocomposite polyaniline (PANI) films with varying concentrations of ZnO and studying their ability to detect ammonia gas. They found that loading 10 at% ZnO in PANI resulted in a gas sensing response of 59% for 120 ppm NH\u003csub\u003e3\u003c/sub\u003e gas. Additionally, they embedded Ag-decorated ZnO nanorods in the PANI matrix using the in-situ oxidative polymerization technique, which showed a response of 70% at 120 ppm and a recovery time of less than 120 s [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eHere, we have presented PANI-ZnO nanocomposite films with varying concentrations of ZnO for NH\u003csub\u003e3\u003c/sub\u003e detection. The physicochemical and optical properties of PANI and PANI-ZnO thin films were explored, along with NH\u003csub\u003e3\u003c/sub\u003e detection. The study demonstrated that the sensing parameters of the PANI-based sensor can be improved by doping ZnO nanoparticles significantly\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Materials and Characterization Techniques\u003c/h2\u003e \u003cp\u003eIn this investigation, all analytical reagent grade (AR grade) chemicals were used without further purification, except for aniline. Aniline, ammonium persulphate, sulfuric acid (H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e), acetone, zinc chloride, and sodium hydroxide pellets were sourced from Loba Chem, India. All reactions were carried out using double distilled water obtained from a laboratory distillation apparatus.\u003c/p\u003e \u003cp\u003eThe PANI and PANI-ZnO thin films were characterized using an X-ray diffractometer (XRD) (Mini Flex II, Rigaku, Japan) with CuKα radiation of wavelength 1.5406 \u0026Aring; and scanning electron microscope (SEM) technique using ZEISS (Gemini SEM 360) from Germany for structural and morphological characterization respectively. The UV\u0026ndash;Vis. spectrum was recorded using a UV\u0026ndash;Vis. fibre-optic spectrophotometer (BLAC-SR, Stellar Net, USA), and functional groups were studied via FTIR spectroscopy using an α-ATR IR-spectrophotometer (Bruker, Japan). All sensor parameters were analysed using a Keithley 6514 electrometer with a data acquisition system controlled by a computer.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Synthesis of ZnO nanoparticles\u003c/h2\u003e \u003cp\u003eThe ZnO nanoparticles were synthesized using the chemical co-precipitation method. First, 0.1 M of Zinc chloride was mixed in 50 ml of DI water using a magnetic stirrer for 30 minutes. In a separate beaker, 0.2 M of sodium hydroxide (NaOH) pellets were dissolved in 50 ml of DI water. The NaOH solution was then added drop by drop into the ZnCl\u003csub\u003e2\u003c/sub\u003e solution over 30 minutes with constant stirring, resulting in the formation of white precipitation. The mixture was left to stir constantly for 2 hours. The obtained precipitation was then filtered using Whatman filter paper and dried at room temperature for 12 hours. The dried material was processed into a fine powder and calcinated at 300\u0026deg;C for 2 hours.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Preparation of PANI and PANI-ZnO thin films\u003c/h2\u003e \u003cp\u003eThe PANI and PANI-ZnO thin films were prepared using a soft chemical method. Figure\u0026nbsp;(1a) illustrates the experimental procedure. To start, equal concentrations (0.1M) of aniline and ammonium persulphate (APS) were mixed with 1M of H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e in 50 ml of distilled water. Prior to the polymerization process, both solutions were cooled for 1 hour to maintain a temperature of approximately 4\u0026deg;C. The aniline solution was stirred by immersing a glass substrate, and the APS solution was added dropwise to it. The dark green PANI film began to deposit over the glass substrate after 15 minutes. The films were removed from the solution after 2 hours, washed with acetone and DI water four times, and then dried at room temperature. The deposition of PANI-ZnO thin films over the substrate same procedure was adopted with slight modification. In the process of forming PANI-ZnO thin films, different concentrations of ZnO nanoparticles (10%, 20%, 30%) were dispersed in an aniline solution using ultrasonication in three separate beakers before the polymerization process. Thereafter, we followed the same procedure as the one used for forming the PANI film.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Material characterization\u003c/h2\u003e \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e \u003ch2\u003e3.1.1 Structural Properties (X-ray diffraction analysis)\u003c/h2\u003e \u003cp\u003eXRD characterization techniques were used to investigate the structural properties of the developed PANI, PANI-ZnO thin films, and ZnO nanoparticles. Figure\u0026nbsp;(2a) depicts the typical XRD patterns of synthesized ZnO nanoparticles, showing the expected diffraction peaks that match well with the ICPDS card. 96-900-4180. ICD. The diffraction peaks observed at 2θ\u0026thinsp;=\u0026thinsp;31.73\u0026deg;, 34.42\u0026deg;, 36.22\u0026deg;, 47.51\u0026deg;, 56.53\u0026deg;, 62.83\u0026deg;, 66.30\u0026deg;, 67.89\u0026deg;, 69.05\u0026deg;, 72.56\u0026deg;, 76.89\u0026deg;, and 67.98\u0026deg; in all diffraction patterns correspond to the (100), (002), (101), (102), (110), (103), (200), (112), (201), (004), and (202) planes for the hexagonal wurtzite phase of ZnO in its polycrystalline form [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. XRD patterns of PANI and PANI-ZnO (10\u0026ndash;30 wt.%) thin films are illustrated in Fig.\u0026nbsp;(2b). PANI exhibits two broad diffraction peaks at approximately 2θ\u0026thinsp;=\u0026thinsp;19.92\u003csup\u003eO\u003c/sup\u003e and 25.51\u003csup\u003eO\u003c/sup\u003e, which are typically attributed to the (110) and (200) planes, respectively. The broad peaks observed indicate that PANI is amorphous with some degree of crystallinity [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. XRD patterns of PANI-ZnO (10, 20, 30 wt.%) composites show higher crystallinity compared to PANI as the concentration of ZnO increases [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. At the highest concentration of 30 wt.%, the diffraction pattern showed more peaks like ZnO, and the peaks shifted towards the lower angle side [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003e3.1.2 Morphological Study of PANI and PANI-ZnO Thin Films\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;(3 a-h) depict the surface morphology of the developed PANI and PANI-ZnO thin films. Figure\u0026nbsp;(3 a-d) display the FESEM images of the PANI and PANI-ZnO thin films at a lower resolution. At this lower resolution, the surface of all films showed good dispersion of materials over the thin films. The pure PANI shows a smooth surface over the substrate, whereas the PANI-ZnO thin films exhibited an uneven, rough surface. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003ee shows the microscopic view of pure PANI, revealing an agglomerated porous structure. Figure\u0026nbsp;(3 f-h) visualize the surface morphology of the PANI-ZnO thin films of different concentrations of ZnO (10\u0026ndash;30 wt.%) at higher resolution. At higher resolution microscopic study reveals that the PANI morphology in amorphous agglomerated structure and the PANI-ZnO (10, 20, 30 wt.%) shows the amorphous nature with dispersion of ZnO nanoparticles. It demonstrates the uniform distribution of ZnO, while also showing a highly porous natured surface.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e \u003ch2\u003e3.1.3 Functional group study (FTIR)\u003c/h2\u003e \u003cp\u003eFTIR spectrum of the developed PANI and PANI-ZnO thin films exhibited the expected peaks with the characteristic peaks, shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003e. The peaks originated at 597 and 696 cm⁻\u0026sup1; in substituted benzenes due to the out-of-plane bending vibrations of C-H bonds in aromatic rings [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. The 786 and 867 cm⁻\u0026sup1; peaks are preferably attributed to out-of-plane bending vibrations of C-H bonds in 1,2,4-trisubstituted benzene rings and aromatic C-H bonds respectively [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. The peak at 1046 cm⁻\u0026sup1; is typically associated with in-plane bending vibrations of C-H bonds in aromatic rings [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. In PANI, C-N stretching vibrations in the benzenoid units are observed at 1244 cm⁻\u0026sup1;, and the 1298 cm⁻\u0026sup1; peak is linked to C-N stretching in the quinoid units [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. Additionally, the benzenoid units show C\u0026thinsp;=\u0026thinsp;C stretching vibrations at 1469 cm⁻\u0026sup1;, with the 1519 cm⁻\u0026sup1; peak indicating C\u0026thinsp;=\u0026thinsp;C stretching in the quinoid units [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. In PANI-ZnO nanocomposites, the peaks exhibit slight shifts to higher wavenumbers due to the ZnO nanoparticles within the PANI matrix [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. The 570 cm⁻\u0026sup1; peak, characteristic of Zn-O stretching vibrations, indicates the presence of ZnO [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. The 3859 cm⁻\u0026sup1; peak relates to O-H stretching vibrations, likely from hydroxyl groups on ZnO, while the 3903 cm⁻\u0026sup1; peak may indicate lattice vibrations in ZnO or interactions between PANI and ZnO at the interface [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. Thus, the FTIR study confirms the existence and interaction of ZnO nanoparticles in the PANI matrix [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003e3.1.4 UV-Vis Spectroscopy\u003c/h2\u003e \u003cp\u003eThe optical properties of the developed PANI and PANI-ZnO thin films were analyzed using UV-Vis. absorption spectroscopy. Figure\u0026nbsp;(5 a) shows the UV-Vis. absorption spectrum of PANI and PANI (10, 20, 30 wt.%) thin films. Both pure PANI and ZnO nanoparticles incorporated PANI thin films showed two absorption peaks. The pure PANI displayed peaks at wavelengths of 341 nm and 606 nm. The 341 nm peak is associated with the π-π* transition of the benzenoid rings in the polyaniline chain, representing the electronic transition from the HOMO to LUMO in the benzenoid units [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. The second peak at 606 nm is attributed to polaron transitions in polyaniline, which are charge carriers in the polymer [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]. In the case of PANI-ZnO thin films, the observed peaks in pure PANI shifted slightly with increasing concentration of ZnO nanoparticles. The shifting of the absorption bands may be due to interactions between PANI and ZnO nanoparticles [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. The bandgaps of the developed films were calculated by analyzing the UV\u0026ndash;Vis. spectra using Tauc's relation as shown in Eq.\u0026nbsp;1 [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e].\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\alpha h\\nu =A {(h\\nu -{E}_{g})}^{2}------------\\left(1\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere, A is a constant, \u003cem\u003eh\u003c/em\u003e is Planck\u0026rsquo;s constant, Eg is the optical band gap, \u003cem\u003ehν\u003c/em\u003e is photon energy, and α is the absorption coefficient for the direct band gap. Figure\u0026nbsp;(5 b) shows the Tauc plot, and bandgaps are shown as 3 eV for PANI, and 2.75, 2.71, and 2.58 eV for PANI-ZnO (at 10%, 20%, and 30% wt.%) respectively. The study of bandgap indicates that as the concentration of ZnO nanoparticles increases, the bandgap of PANI decreases.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"4. Sensor Performance","content":"\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e4.1.1 Sensitivity and Detection Limit\u003c/h2\u003e \u003cp\u003eThe sensitivity of the developed gas sensors merely depends upon the physicochemical and optoelectrical properties of used materials. Sensing parameters of the developed PANI and PANI-ZnO thin films were examined for different concentrations of NH\u003csub\u003e3\u003c/sub\u003e gas by chemiresistive modality. In this investigation, lower concentrations (5\u0026ndash;50 ppm) shown in Fig.\u0026nbsp;(6 a) and higher concentrations (100\u0026ndash;500 ppm) Fig.\u0026nbsp;(6 b) of NH\u003csub\u003e3\u003c/sub\u003e were studied to analyse the sensor parameters. The sensitivity of the developed sensors was examined by the change in resistance with respect to time with exposure and removal of various concentrations of NH\u003csub\u003e3\u003c/sub\u003e. The sensitivity of the sensor is defined as:\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e\n$$S \\left(\\%\\right)=\\frac{({R}_{target gas}-{R}_{air})}{{R}_{air}}\\times 100 -------\\left(2\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere R \u003csub\u003etarget gas\u003c/sub\u003e and R \u003csub\u003eair\u003c/sub\u003e represent the resistances of the sensor film in the presence of target gas and air, respectively. At room temperature for concentrations of 10\u0026ndash;50 ppm and it exhibited the rapid change in resistance and then reached saturation. The change in the resistance by exposing NH\u003csub\u003e3\u003c/sub\u003e occurs due to the removal of free electrons from the conduction band of the composite by the adsorbed oxygen species which act as trapped states. The developed sensor elements show an excellent response towards the NH\u003csub\u003e3\u003c/sub\u003e with high selectivity. Compared to the PANI-based sensor, the PANI-ZnO sensor increases the sensing response by 9-fold and it enhances more when the ZnO concentration in PANI. The linearity of the response was demonstrated by linear fitting (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e6\u003c/span\u003ec) and it shows the R\u003csup\u003e2\u003c/sup\u003e value of 0.997, it confirmed the excellence of the developed sensors. The lower detection limit for the developed thin film-based sensor is 5 ppm, as the measurable response is shown for this concentration.\u003c/p\u003e \u003cdiv id=\"Sec14\" class=\"Section3\"\u003e \u003ch2\u003e4.1.2 Selectivity\u003c/h2\u003e \u003cp\u003eThe selectivity of the developed PANI-ZnO thin film-based sensor was tested by exposing the different interference species such as methanol, carbon dioxide, ethanol, and nitrogen dioxide. Figure\u0026nbsp;(6 d) shows the selective response of the PANI-ZnO (30%) film to NH\u003csub\u003e3\u003c/sub\u003e compared to the mentioned species for a 400 ppm concentration at room temperature. The PANI-ZnO thin film exhibited the highest response compared to the negligible response of the other checked interference species. This indicates that the PANI-ZnO nanocomposite-based sensor has the promising capability to detect NH\u003csub\u003e3\u003c/sub\u003e gas with very high selectivity.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e \u003ch2\u003e4.1.3 Response Time, Recovery Time, and Stability\u003c/h2\u003e \u003cp\u003eThe response and recovery time of the developed sensor confirms its usefulness in practical applications. The response and recovery time were measured by recording the time it took for the sensor's response to reach 90% of its saturation value (Rg) when exposed to the gas, as well as the time it took for the sensor to drop to 10% of its initial value (Ra) when the gas was removed. For the PANI-based sensor, the response time shown as ~\u0026thinsp;70 seconds, and the recovery time is ~\u0026thinsp;100 seconds for 100 ppm NH\u003csub\u003e3\u003c/sub\u003e gas. However, the response and recovery times decrease significantly for all PANI-ZnO thin films compared to PANI film. For PANI-ZnO (30%), the response time is approximately 45 seconds, and the recovery time is approximately 70 seconds. The stability of the developed thin films towards NH\u003csub\u003e3\u003c/sub\u003e was measured for 45 days, with a change in response measured every 5 days as shown in Fig.\u0026nbsp;(6 e). The PANI film demonstrates 69% stability, while PANI-ZnO (30%) shows a 96% stable response during the measured period. Thus, the study exhibited that PANI-based sensors can enhance stability by doping the ZnO nanoparticles.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eIn the current study, we have successfully developed PANI and PANI-ZnO thin films using a soft chemical method. We have analysed the structural, morphological and optical properties of the thin films using techniques such as XRD, FESEM, FTIR, and UV-Vis. spectroscopy etc. The developed thin films were employed to detect NH\u003csub\u003e3\u003c/sub\u003e using chemiresistive technique modality. We evaluated the performance of sensors by examining parameters such as sensitivity, reproducibility, selectivity, stability etc. The sensors exhibited excellent response to NH\u003csub\u003e3\u003c/sub\u003e concentrations ranging from 5\u0026ndash;50 ppm as low concentrations and 100\u0026ndash;500 ppm as high concentrations at room temperature. The lowest detection limit of the thin films was found to be 5 ppm, and they demonstrated superior selectivity when tested against various interfering substances. In summary, PANI-based sensors can effectively detect NH\u003csub\u003e3\u003c/sub\u003e gas at ambient temperature, and the sensing capabilities of these sensors were significantly improved by doping ZnO nanoparticles.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflict of Interest\u003c/h2\u003e \u003cp\u003eThe authors declared no conflict of Interest.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAuthor contributionsSPD: Experimental work, data analysis and drafting ofmanuscript, YPG: Data analysis, drafting of the manuscript,CTB : Planning of experiments, draftingand editing of the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eSPD : gratefully acknowledges to the UGC for National fellowship for doctor of philosophy as financial assistance\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eGanguly, T., Selvaraj, K. L., \u0026amp; Guttikunda, S. K. (2020). National Clean Air Programme (NCAP) for Indian cities: Review and outlook of clean air action plans. Atmospheric Environment: X, 8, 100096.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang, Z., Hua, P., Li, R., Bai, Y., Fan, G., Wang, P., \u0026hellip; Krebs, P. (2019). Concentration decline in response to source shift of trace metals in Elbe River, Germany: a long-term trend analysis during 1998\u0026ndash;2016. Environmental pollution, 250, 511\u0026ndash;519.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSapek, A. (2013). Ammonia emissions from non-agricultural sources. Polish Journal of Environmental Studies, 22(1).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDadhich, J. P., Smith, J. P., Iellamo, A., \u0026amp; Suleiman, A. (2021). Climate change and infant nutrition: estimates of greenhouse gas emissions from milk formula sold in selected Asia Pacific countries. Journal of Human Lactation, 37(2), 314\u0026ndash;322.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKlaassen, C. D., \u0026amp; Amdur, M. O. (Eds.). (2013). Casarett and Doull's toxicology: the basic science of poisons (Vol. 1236, pp. 189\u0026ndash;190). New York: McGraw-Hill.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrintlinger, T., Herzing, A. A., Long, J. P., Vurgaftman, I., Stroud, R., \u0026amp; Simpkins, B. S. (2015). Optical dark-field and electron energy loss imaging and spectroscopy of symmetry-forbidden modes in loaded nanogap antennas. ACS nano, 9(6), 6222\u0026ndash;6232.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBag, A., \u0026amp; Lee, N. E. (2021). Recent advancements in development of wearable gas sensors. Advanced Materials Technologies, 6(3), 2000883.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBousiotis, D., Alconcel, L. N. S., Beddows, D. C., Harrison, R. M., \u0026amp; Pope, F. D. (2023). Monitoring and apportioning sources of indoor air quality using low-cost particulate matter sensors. Environment International, 174, 107907.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang, Z., Zhu, L., Sun, S., Wang, J., \u0026amp; Yan, W. (2021). One-dimensional nanomaterials in resistive gas sensor: From material design to application. Chemosensors, 9(8), 198.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXiao, Y., Li, H., Wang, C., Pan, S., He, J., Liu, A., \u0026hellip; Lu, G. (2024). Room temperature wearable gas sensors for fabrication and applications. Advanced Sensor Research, 3(3), 2300035.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen, J., Rong, F., \u0026amp; Xie, Y. (2023). Fabrication, Microstructures and Sensor Applications of Highly Ordered Electrospun Nanofibers: A Review. Materials, 16(9), 3310.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSingh, E., Meyyappan, M., \u0026amp; Nalwa, H. S. (2017). Flexible graphene-based wearable gas and chemical sensors. ACS applied materials \u0026amp; interfaces, 9(40), 34544\u0026ndash;34586.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eQue, H., Yan, X., Guo, B., Ma, H., Wang, T., Liu, P., \u0026hellip; Yan, Y. (2019). Terminal deoxynucleotidyl transferase and rolling circle amplification induced G-triplex formation: A label-free fluorescent strategy for DNA methyltransferase activity assay. Sensors and Actuators B: Chemical, 291, 394\u0026ndash;400.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNamsheer, K., \u0026amp; Rout, C. S. (2021). Conducting polymers: a comprehensive review on recent advances in synthesis, properties and applications. RSC advances, 11(10), 5659\u0026ndash;5697.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRajput, V. S., \u0026amp; Bhinder, J. (Eds.). (2023). Advanced Materials for Biomedical Applications: Development and Processing. Springer Nature.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSingh, P., \u0026amp; Shukla, S. K. (2020). Advances in polyaniline-based nanocomposites. Journal of materials science, 55(4), 1331\u0026ndash;1365.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLawaniya, S. D., Kumar, S., Yu, Y., Mishra, Y. K., \u0026amp; Awasthi, K. (2024). Metal oxide-polymer composites for gas-sensing applications. In Complex and Composite Metal Oxides for Gas VOC and Humidity Sensors Volume 1 (pp. 107\u0026ndash;150). Elsevier.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXia, Y., Li, R., Chen, R., Wang, J., \u0026amp; Xiang, L. (2018). 3D architectured graphene/metal oxide hybrids for gas sensors: A review. Sensors, 18(5), 1456.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShakeel, A., Rizwan, K., Farooq, U., Iqbal, S., \u0026amp; Altaf, A. A. (2022). Advanced polymeric/inorganic nanohybrids: An integrated platform for gas sensing applications. Chemosphere, 294, 133772.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJadoun, S., Y\u0026aacute;\u0026ntilde;ez, J., Mansilla, H. D., Riaz, U., \u0026amp; Chauhan, N. P. S. (2022). Conducting polymers/zinc oxide-based photocatalysts for environmental remediation: a review. Environmental chemistry letters, 20(3), 2063\u0026ndash;2083.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEriksson, J., Khranovskyy, V., S\u0026ouml;derlind, F., K\u0026auml;ll, P. O., Yakimova, R., \u0026amp; Spetz, A. L. (2009). ZnO nanoparticles or ZnO films: A comparison of the gas sensing capabilities. Sensors and Actuators B: Chemical, 137(1), 94\u0026ndash;102.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAllameh, P. (2014). Photocurrent Enhancement of Hematite Nanowires by Gold Underlayer Deposition and Ti Doping (Doctoral dissertation, UC San Diego).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBhati, V. S., Hojamberdiev, M., \u0026amp; Kumar, M. (2020). Enhanced sensing performance of ZnO nanostructures-based gas sensors: A review. Energy Reports, 6, 46\u0026ndash;62.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKaur, R., Lawaniya, S. D., Kumar, S., Saini, N., \u0026amp; Awasthi, K. (2023). Nanoarchitectonics of polyaniline\u0026ndash;zinc oxide (PANI\u0026ndash;ZnO) nanocomposite for enhanced room temperature ammonia sensing. Applied Physics A, 129(11), 765.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBai, Y. Dong, X., Guo, C., Xu, Y., Wang, B., \u0026amp; Cheng, X. (2022). Spray synthesis of rapid recovery ZnO/polyaniline film ammonia sensor at room temperature. Frontiers of Materials Science, 16(4), 220620.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKarmakar, N., Jain, S., Fernandes, R., Shah, A., Patil, U., Shimpi, N., \u0026amp; Kothari, D. (2023). Enhanced sensing performance of an ammonia gas sensor based on Ag-decorated ZnO nanorods/polyaniline nanocomposite. ChemistrySelect, 8(18), e202204284.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePaul, S., \u0026amp; Ban, D. K. (2014). Synthesis, characterization and the application of ZnO nanoparticles in biotechnology. Int. J. Adv. Chem. Eng. Biol. Sci, 1(1), 1\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePardeshi, S. K., \u0026amp; Patil, A. B. (2009). Effect of morphology and crystallite size on solar photocatalytic activity of zinc oxide synthesized by solution free mechanochemical method. Journal of Molecular Catalysis A: Chemical, 308(1\u0026ndash;2), 32\u0026ndash;40.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi, D., Huang, J., \u0026amp; Kaner, R. B. (2009). Polyaniline nanofibers: a unique polymer nanostructure for versatile applications. Accounts of chemical research, 42(1), 135\u0026ndash;145.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhu, J., Shao, C., Li, X., Han, C., Yang, S., Ma, J., \u0026hellip; Liu, Y. (2018). Immobilization of ZnO/polyaniline heterojunction on electrospun polyacrylonitrile nanofibers and enhanced photocatalytic activity. Materials Chemistry and Physics, 214, 507\u0026ndash;515.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShah, M., Khan, N., Imran, Z., Khan, M., Khattak, A., Khan, A., \u0026amp; Ullah, N. (2019). Structural, optical and impedance spectroscopy study of thin film of polyaniline (PANI/ZnO) nanocomposite. Materials Research Express, 7(1), 015314.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGiripunje, S. M., \u0026amp; Ghushe, J. (2013). Nanocomposite of polyaniline and ZnO: Preparation, characterisation, optical and electrical properties. Journal of Nano Research, 24, 123\u0026ndash;132.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlamgeer, Tahir, M., Sarker, M. R., Ali, S., Ibraheem, Hussian, S., \u0026hellip; Mohd Said, S. (2023). Polyaniline/ZnO Hybrid Nanocomposite: Morphology, Spectroscopy and Optimization of ZnO Concentration for Photovoltaic Applications. Polymers, 15(2), 363.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAndreas, R., Lesbani, A., \u0026amp; Yusuf, F. A. (2019, April). The characteristics (compositions, morphological, and structure) of nanocomposites polyaniline (PANI)/ZnO. In IOP Conference Series: Materials Science and Engineering (Vol. 509, No. 1, p. 012126). IOP Publishing.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWorkman Jr, J. J. (1996). Interpretive spectroscopy for near infrared. Applied Spectroscopy Reviews, 31(3), 251\u0026ndash;320.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eQuillard, S., Louarn, G., Lefrant, S., \u0026amp; MacDiarmid, A. G. (1994). Vibrational analysis of polyaniline: A comparative study of leucoemeraldine, emeraldine, and pernigraniline bases. Physical Review B, 50(17), 12496.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIbrahim, K. A. (2017). Synthesis and characterization of polyaniline and poly (aniline-co-o-nitroaniline) using vibrational spectroscopy. Arabian Journal of Chemistry, 10, S2668-S2674.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePatil, S. L., Pawar, S. G., Chougule, M. A., Raut, B. T., Godse, P. R., Sen, S., \u0026amp; Patil, V. B. (2012). Structural, morphological, optical, and electrical properties of PANi-ZnO nanocomposites. International Journal of Polymeric Materials, 61(11), 809\u0026ndash;820.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNoei, H., Qiu, H., Wang, Y., L\u0026ouml;ffler, E., W\u0026ouml;ll, C., \u0026amp; Muhler, M. (2008). The identification of hydroxyl groups on ZnO nanoparticles by infrared spectroscopy. Physical Chemistry Chemical Physics, 10(47), 7092\u0026ndash;7097.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGhanbari, K., \u0026amp; Moloudi, M. (2016). Flower-like ZnO decorated polyaniline/reduced graphene oxide nanocomposites for simultaneous determination of dopamine and uric acid. Analytical biochemistry, 512, 91\u0026ndash;102.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang, Y., Hu, J., \u0026amp; Guo, Q. (2019). FTIR and lattice vibrations in ZnO nanoparticles within PANI matrix. Materials Letters, 237(1), 209\u0026ndash;213.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRamya, K., \u0026amp; Subramaniam, K. (2020). Optical Properties of Polyaniline Thin Films. Journal of Materials Science, 55(5), 2567\u0026ndash;2578.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSingh, P., Kaur, G., \u0026amp; Sharma, V. (2021). UV-Vis Spectroscopic Analysis of Conducting Polymers. Spectroscopy Letters, 54(3), 156\u0026ndash;165.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJain, R., Kothari, A., \u0026amp; Malhotra, B. (2019). Interaction Mechanism of PANI-ZnO Nanocomposites. Nanotechnology Reviews, 8(2), 234\u0026ndash;243.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKumar, S., Verma, A., \u0026amp; Sharma, S. (2018). Bandgap Analysis of ZnO Nanoparticles. Applied Nanoscience, 8(6), 1215\u0026ndash;1222.\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":"Conducting Polymer Nanocomposite, Thin Films, Polyaniline-Zinc oxide, Physicochemical Properties, Ammonia sensor","lastPublishedDoi":"10.21203/rs.3.rs-4603844/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4603844/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eRecently, owing to the versatile properties of conducting polymer-nanomaterial composite thin films have been extensively employed in diverse applications. Within this framework, the present investigation reported the NH\u003csub\u003e3\u003c/sub\u003e gas sensing ability of zinc oxide nanoparticles doped polyaniline (PANI-ZnO) composite thin films along with physicochemical and optoelectronic properties. The PANI-ZnO nanocomposite thin films were harvested using a soft chemical polymerisation technique over a glass substrate. The physicochemical and optoelectronic properties of the developed thin films were explored using the XRD, FESEM, UV-Vis. and FTIR characterisation techniques. The NH\u003csub\u003e3\u003c/sub\u003e gas sensing properties of PANI and PANI-ZnO nanocomposite thin film at ambient temperature were studied using the chemiresistive sensing technique. The developed PANI-ZnO sensor exhibited an excellent response toward the target NH\u003csub\u003e3\u003c/sub\u003e gas with outstanding sensitivity, selectivity, linearity, and stability. Comparatively, the PANI-ZnO thin films show enhanced sensitivity, stability, response and recovery time than the PANI film. Thus, the present study declared that the developed PANI-ZnO thin films are promising candidates for low-concentration detection of NH\u003csub\u003e3\u003c/sub\u003e gas with appropriate response and recovery time.\u003c/p\u003e","manuscriptTitle":"Investigating the Physicochemical and Optical Properties of PANI and PANI-ZnO Thin Films for an Efficient Ammonia Sensor at Ambient Conditions","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-19 04:43:39","doi":"10.21203/rs.3.rs-4603844/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":"eb2c8b1e-3bc3-45b3-9351-cad5e86b23d7","owner":[],"postedDate":"July 19th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-07-20T10:51:31+00:00","versionOfRecord":[],"versionCreatedAt":"2024-07-19 04:43:39","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4603844","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4603844","identity":"rs-4603844","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}