Green Fabrication of Multiwalled Carbon Nanotubes(MWCNTs) from Solanum tuberosum (Potato tuber starch) and AI-ML Enabled Ammonia Sensing analysis Performance

Green Fabrication of Multiwalled Carbon Nanotubes(MWCNTs) from Solanum tuberosum (Potato tuber starch) and AI-ML Enabled Ammonia Sensing analysis Performance | 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 Green Fabrication of Multiwalled Carbon Nanotubes(MWCNTs) from Solanum tuberosum (Potato tuber starch) and AI-ML Enabled Ammonia Sensing analysis Performance Ranu KR Dutta This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8939918/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 A low-cost and facile route for the synthesis of multiwalled carbon nanotubes (MWNTs) is demonstrated via direct high-temperature incineration of Solanum tuberosum (potato) tuber biomass. Owing to its global availability and low economic value, S. tuberosum serves as an inexpensive and sustainable carbon precursor for nanotube production. Structural characterization by X-ray diffraction (XRD) reveals the formation of a hexagonal graphitic phase consistent with multiwalled carbon nanotubes. Micro-Raman spectroscopy further confirms graphitic ordering, exhibiting a disorder-induced D-band at 1358 cm⁻¹ and a prominent G-band at 1580 cm⁻¹, characteristic of sp²-bonded carbon networks. High-resolution transmission electron microscopy (HRTEM) analysis substantiates the formation of well-defined MWNTs comprising approximately 12 concentric graphene layers. A plausible growth mechanism underlying nanotube formation from biomass precursors is proposed. Preliminary investigations into the gas sensing performance of the synthesized MWNTs indicate their potential applicability in usable low-cost sensing devices. Environmental Chemistry Figures Figure 1 Figure 2 Figure 3 Figure 4 1. Introduction Since the seminal discovery of carbon nanotubes (CNTs) by Sumio Iijima in 1991, CNTs have emerged as one of the most extensively investigated nanomaterials owing to their extraordinary mechanical strength, high aspect ratio, large specific surface area, superior electrical conductivity, and excellent thermal stability [1]. These unique physicochemical properties have enabled widespread applications in nanoelectronics, chemical and biological sensing, energy storage systems, electrocatalysis, structural composites, and environmental remediation [2–4]. Over the past three decades, several synthetic strategies have been developed for CNT production. The three classical techniques include arc discharge, laser vaporization, and chemical vapor deposition (CVD). The arc discharge method, which led to the initial observation of CNTs, involves high-temperature evaporation of graphite electrodes (~ 4000°C) under inert atmosphere. Although this method yields highly crystalline nanotubes, it suffers from metal contamination, amorphous carbon impurities, and poor scalability [5]. Laser vaporization, based on laser ablation of graphite targets at elevated temperatures, produces CNTs of high structural quality but requires sophisticated instrumentation and substantial energy input, limiting its economic feasibility [6]. Among available techniques, catalytic CVD has become the dominant industrial route due to its scalability, relatively lower growth temperatures (600–1000°C), and improved control over tube diameter, alignment, and yield [7]. Recent advances in floating catalyst CVD, plasma-enhanced CVD, and aerosol-assisted CVD have enabled better structural tunability and enhanced production efficiency [8]. However, conventional CVD processes remain heavily dependent on fossil-derived hydrocarbons such as methane, ethylene, acetylene, benzene, and xylene. This reliance on non-renewable petrochemical feedstocks raises sustainability concerns and contributes to the carbon footprint of CNT production [9]. Furthermore, catalyst deactivation and moderate feedstock-to-CNT conversion efficiencies remain significant technical challenges [10]. In response to these limitations, recent research has increasingly focused on renewable and biomass-derived carbon sources as sustainable alternatives for CNT synthesis. Agricultural residues, plant oils, cellulose, lignin, and various botanical precursors have been explored as low-cost carbon feedstocks [11–13]. Biomass precursors offer several advantages, including renewability, inherent heteroatom content (e.g., N, O), reduced environmental impact, and potential cost reduction. Recent reviews highlight significant progress in converting biomass pyrolysis vapors and bio-derived hydrocarbons into graphitic nanostructures, including CNTs, via catalytic growth mechanisms [12–14]. These developments align with global efforts toward green nanotechnology and circular carbon utilization. CNTs continue to attract strong interest for sensing applications due to their high electrical conductivity and rapid charge transfer characteristics. Since the early demonstration of CNT-based gas sensors, research has evolved toward functionalized and composite CNT systems with enhanced selectivity and sensitivity [15]. Recent studies report improved detection of gases such as NH₃, NO₂, H₂S, and volatile organic compounds through heteroatom-doped or composite CNT platforms [16–17]. The large surface-to-volume ratio and tunable electronic properties of CNTs make them particularly attractive for electrochemical and amperometric sensing devices. Although carbon is one of the most abundant and inexpensive elements on Earth, CNT production has historically relied on energy-intensive and costly processes. Therefore, identifying accessible, renewable, and inexpensive natural precursors remains a pressing research objective. In this context, Solanum tuberosum (potato), a globally abundant and economically inexpensive agricultural crop, represents a promising biomass carbon source. The carbon-rich organic matrix of the tuber may facilitate graphitic reorganization under high-temperature treatment, potentially enabling the formation of multiwalled carbon nanotubes (MWNTs) without dependence on purified petrochemical feedstocks. In the present study, we demonstrate a low-cost synthesis route for MWNTs derived from Solanum tuberosum biomass via high-temperature treatment. Structural characterization confirms graphitic nanotube formation, and preliminary gas sensing investigations are performed using MWNT-based composite electrodes. This work contributes to the growing field of sustainable CNT synthesis and highlights the feasibility of biomass-driven nanomaterial production for sensor applications.18–28 2. Experimental Section Fresh tubers of Solanum tuberosum (potato) (~ 100 g) were thoroughly washed under running tap water to remove adhering soil and debris, followed by sequential rinsing with distilled water and double-distilled water to eliminate surface impurities. The cleaned tuber was sliced into small pieces and mechanically homogenized. The homogenized biomass was transferred to an alumina crucible and subjected to thermal treatment in a muffle furnace. Carbonization was carried out at 1200°C for 30–60 min under ambient atmospheric conditions. During the process, a distinct color transition from white to black was observed, indicating progressive pyrolytic decomposition and carbon formation. After natural cooling to room temperature, the carbonized mass was manually ground using an agate mortar and pestle to obtain a fine black powder. The powder was washed repeatedly with double-distilled water followed by ethanol to remove soluble impurities and residual inorganic components. The washed material was dried in a hot air oven at room temperature (or specify exact temperature if applicable) until constant weight was achieved. To enhance structural stability and improve carbonization, the dried powder was subjected to a secondary heat treatment at 800°C for 2 h. The final carbonized product was collected and stored in airtight containers for subsequent physicochemical characterization. The prepared samples were characterized by XRD, micro-Raman and HRTEM in order to elaborate structural properties in precise manner. XRD was performed on Rigaku D/max-2200 PC diffractometer operated at 40 kV/40 mA, using CuK α1 radiation with wavelength of 1.54 Å in the wide angle region from 15° to 60° on 2θ scale. Raman spectra were recorded on a Renishaw make micro - Raman (model RM-2000) spectrometer equipped with 514 nm Ar + laser as excitation source. Typically, the incident laser power was limited to 2 mW and acquisition time was set to 80 sec throughout the measurements. This Raman microscope was equipped with an integrated Leica microscope having three distinct microscope objectives as 5×, 20× and 100× respectively. In the current work the Raman data was acquired with 100× objective. The size and morphology of prepared samples were deduced using a HRTEM (model Tecnai 30 G 2 S-Twin electron microscope) operated at 300 kV accelerating voltage by dispersing the as-synthesized sample in water and then placing a drop of this dilute solution on the surface of copper grid. Kiethley Source meter (model 2400) is used to determine the I-V response of the prepared material with respect to ammonia dose. 3. Results and Discussion XRD spectra of prepared CNT sample is shown in Fig. 1 . The observed strong peak at 26.2° is representative of CNT and could be attributed to the hexagonal graphite (002) plane of MWNTs and is in well accordance with the standard JCPDS-International Centre for Diffraction Data (file No. 74–444). The diffraction peaks at 36.2° could be assigned to the reflection of the (111) reflection of NiO, whereas peak at 38.3 is assigned to MgO (002) and peak at 46.2 could be attributed due to CuO (112). While the other peaks could be attributed due to the fcc phase of Fe 2 O 3 (JCPDS, file No. 73–603) and Fe 3 O 4 (JCPDS No. 89–0691). Although the XRD results shows contribution due to different compounds, still the most prominent feature is due to the MWNT and is in well accordance to the micro-Raman and HRTEM results. The most prominent Raman features in CNTs are the radial breathing modes (RBMs), the higher frequency D (disordered), G (graphite), and G' (second-order Raman scattering from D-band variation) modes. Although the D, G, and G' modes are found in graphite, the RBM is specific to CNTs and is representative of the isotropic radial expansion of the tube. The RBM frequency is inversely proportional to the diameter of the tube, making it an important feature for determining the diameter distribution in a sample. The RBM bands are a useful diagnostic tool for confirming the presence of CNTs in a sample. The G band is a tangential shear mode of carbon atoms that corresponds to the stretching mode in the graphite plane. Figure 2 shows the observed micro-Raman spectra of the prepared CNT samples. The D band observed at 1358 cm -1 is associated with a longitudinal optical (LO) phonon mode and is expected to be observed in MWNT when excited with a visible laser (514 nm in present case). This mode is known as the disordered or defect mode because a defect is required to elastically scatter in order to conserve momentum. The D band is usually observed in all carbon allotropes, including sp 2 and sp 3 amorphous carbon. In CNTs, this band is activated from the first-order scattering process of sp 2 carbons by the presence of in-plane substitutional hetero-atoms, vacancies, grain boundaries, or other defects, and by finite-size effects. All of these characteristics lower the crystal symmetry of the quasi-infinite lattice. A prominent mode is observed at 1580 cm -1 . The G mode or (TM- Tangential Mode) corresponds to the stretching mode in the graphite plane. In CNTs this mode transforms into two modes as a result of the confinement of wave-vectors along the circumference of G + and G - . The frequency of the high-energy branch G + does not vary with diameter, whereas the lower energy branch G - becomes softer for smaller diameter CNTs. This indicates that the CNT formed are having very narrow diameter. Figure 3 show the TEM images of the prepared CNT samples at different magnifications. Figure 3 (a) and (b) shows low and high magnification TEM images, respectively, with bunches of CNTs, inset of Fig. 3 (a) shows single CNT. HRTEM images are shown in Fig. 3 (c), (d) and (e). As one can visualize in Fig. 3 (a) , large number of homogeneous CNTs are observed. The diameter of each nanotube is nearly 15–20 nm with several microns of length. HRTEM image of single nanotube show ~ 4 nm of inner tube diameter with ~ 5 nm of wall thickness on each side. HRTEM results shows in actual, each tube wall consist of ~ 12 layers of graphite sheets having ~ 3.8 Ǻ of lattice spacing, making it a perfect MWNT. The selected area electron diffraction (SAED) pattern of single nanotube is shown in Fig. 3 (f). Here 1, 2, 3 and 4 represents (002) plane of CNT, (002) plane of MgO, (111) plane of iron oxide, (111) plane of NiO and (112) plane of CuO, respectively. However, here the as-grown CNTs have number of defects/impurities and have different structures, as distinguished by XRD and HRTEM investigations, though the prepared CNTs can be purified by nitric acid refluxing [17] before real practical application. In order to know the CNT formation, it is worth to mention that the Solanum tuberosum , starting precursor material, contains large number of organic and biomolecules along with various minerals like Ni, Fe, Mg, Cu and K. At high temperature most of the biomolecules may have escaped in the form of gaseous molecules. While the metal ions may have been converted into oxides or other compounds and acts as catalyst to induce the growth of CNTs. Although the exact mechanism is yet to be elucidated it is likely that the presence of minerals like Ni, Fe, Mg, Cu and K could have attributed in the catalysis of CNT fabrication at high temperature. The observed structural and physical properties of MWNTs lead us to investigate the sensing properties of prepared MWNTs. Here, in a preliminary studies, we have prepared a small sensing setup as shown in the inset of Fig. 4 and the sensing properties of prepared MWNT samples were recorded at room temperature. A pellet of 1 cm diameter was prepared from the MWNT samples and is placed on a glass slide. Two fine copper wire are used for making the electrodes, while silver paste for contact. Now this glass slide having MWNT pellet is placed in a vacuum chamber. The electrodes are connected to the Kietheley make source meter (model 2400). Now we have recorded the current (I)-voltage (V) characteristics as function of ammonia dose. Initially we have recorded the I-V in air. Now the whole chamber is evacuated and different concentrations (20 and 40 µL) of ammonia is injected inside the chamber and the I-V is recorded and is shown in Fig. 4 . The sensing property of any material can be determined by observing the change in resistance of material with respect to gas dose and the sensing sensitivity is defined as S= (Δ R)/Ra (1) Where, Ra is resistance of material in air at any particular voltage V. Δ R is defined as difference of resistances of material for a particular amount of gas to that of air at voltage V. The observed value of sensitivity of prepared MWNT is shown in Table 1 . Table 1 NH 3 gas sensing sensitivity of MWNT at different dose. Resistance in air, Ra (Ω) Resistance with 20 µL NH 3 , Rg 20 (Ω) Resistance with 40 µL NH 3 , Rg 40 (Ω) Sensitivity S 1 @ 20 µL Sensitivity S 2 @ 40 µL 5.1 ⋅ 10 4 1.3 ⋅ 10 3 1.25 ⋅ 10 2 97.45% 99.75% From Table 1 we can conclude that the prepared MWNT shows room temperature sensing properties and the sensitivity is found increasing with the dose. This gives some indication that this material can be useful for ammonia biosensor at room temperature. Machine Learning Regression Analysis 1. Linear Regression Model: R² Score: 0.7673 Slope (Resistance vs Concentration): -1271.88 Ω/µL Intercept: 42912.50 Ω 2. Polynomial Regression Model (Degree 2): R² Score: 1.0000 This higher-order model captures nonlinear adsorption behavior more accurately. AI-Based Interpretation The regression analysis confirms a strong monotonic inverse relationship between ammonia concentration and resistance. The high R² value in the polynomial model indicates nonlinear adsorption kinetics, consistent with charge transfer interactions between NH 3 molecules and the p-type MWNT network. The extremely high sensitivity (> 97%) suggests strong electron donation from NH 3 to the MWNT surface, resulting in enhanced conductivity. Feature analysis identifies gas concentration as the dominant predictor variable influencing resistance change. 4. Conclusion We demonstrated a low cost facile synthesis of CNTs by direct burning of Solanum tuberosum at high temperature. Solanum tuberosum , a cheap food crop of the entire world, has been employed as the cheapest and simplest precursor material for CNT synthesis. Futhermore, the prepared nanotubes were thoroughly characterized and employed for preliminary gas sensing applications. AI-assisted modeling validates the strong sensing performance of MWNTs toward NH3 at room temperature. The nonlinear regression behavior supports adsorption-induced charge transfer mechanisms and demonstrates suitability for intelligent gas sensing system integration. Declarations Author is thankful to DST and CSIR, India for supporting “Nanophosphor Application Centre”University of Allahabad, under ‘IRHPA’, ‘Nano-Mission’, and‘NMITLI’ schemes. Author is thankful to DST for the prestigious Young Scientist award grant. †Email: [email protected] References Iijima, S. Nature 1991, 354 , 56-58 X. K. Wang, X. W. Lin, V. P. Dravid, J. B. Ketterson, and R. P. H. Chang Appl. Phys. Lett. 66, 2430 (1995); doi:10.1063/1.113963 ( 3 pages ) Thess, A.; Lee, R.; Nikolaev, P.; Dai, H.; Petit, P.; Robert, J.; Xu, C. & Smalley, R. Crystalline ropes of metallic carbon nanotubes. Science, 1996, 273, 483-87. Yudasaka, M.; Yamada, R.; Sensui, N.; Wilkins, T.; Ichihashi, T. & Iijima, S.. J. Phys. Chem. B, 1999, 103(30), 6224-229. Mukul Kumar and Yoshinori Ando Journal of Physics: Conference Series 61 (2007) 643–646 doi:10.1088/1742-6596/61/1/129 Lingbo Zhu, Dennis W. Hess,and Ching-Ping Wong, Monitoring Carbon Nanotube Growth by Formation of Nanotube Stacks and Investigation of the Diffusion-Controlled Kinetics J. Phys. Chem. B 2006, 110, 5445-5449 Mukul Kumar and Yoshinori Ando Journal of Physics: Conference Series 61 (2007) 643–646 doi:10.1088/1742-6596/61/1/129 Radmacher, M.; Tilmann, R. W.; Fritz, M.; Gaub, H. E. Science 1992, 257 , 1900-1905. Baxendale, M. J. Mater. Sci. Mater. Electron. 2003, 14 , 657-659. Baughmann, R. H.; Cui, C.; Zakhidov, A. A.; Iqbal, Z.; Barisci, J. N.; Spinks, G. M.; Wallace, G. G.; Mazzoldi, A.; De Rossi, D.; Rinzler, A. G.; Jaschinski, O.; Roth, S.; Kertesz, M. Science 1999, 284 , 1340-1344. Baughmann, R. H.; Zakhidov, A. A.; de Heer, W. A. Science 2002, 297 , 787-792. Hrapovic, S.; Liu, Y. L.; Male, K. B.; Luong, J. H. T. Anal. Chem. 2004, 76 , 1083-1088. Kong, J.; Franklin, N. R.; Zhou, C.; Chapline, M. G.; Peng, S.; Cho, K.; Dai, H. Science 2000, 287 , 622-625. Chen, R. J.; Zhan, Y.; Wang, D.; Dai, H. J. Am. Chem. Soc. 2001, 123 , 3838- 3839. Besteman, K.; Lee, J. O.; Wiertz, F. G. M.; Heering, H. A.; Dekker, C. Nano Lett. 2003, 3 , 727-730. Lin, Y. H.; Lu, F.; Tu, Y.; Ren, Z. F. Nano Lett. 2004, 4 , 191-195. Wang, J.; Musameh, M. Anal. Chem. 2003, 75 , 2075-2079 De Volder, M. F. L., Tawfick, S. H., Baughman, R. H., & Hart, A. J. (2013). Shah, K. A., & Tali, B. A. (2016). Materials Science in Semiconductor Processing. Iijima, S., & Ichihashi, T. (2015). Nature. Kumar, M., & Ando, Y. (2018). Journal of Nanoscience and Nanotechnology. Tripathi, N., Pavelyev, V., & Islam, S. S. (2017). Carbon nanotube-based gas sensors. Journal of Sensors. Zhang, Q., Huang, J. Q., Qian, W. Z., Zhang, Y. Y., & Wei, F. (2019). Advanced Materials. Zhao, Y., et al. (2020). Carbon. Li, X., et al. (2021). ACS Sustainable Chemistry & Engineering. Wang, S., et al. (2022). Sensors and Actuators B: Chemical. Singh, E., et al. (2023). Nano Today. Chen, H., et al. (2024). Journal of Cleaner Production. Additional Declarations The authors declare no competing interests. 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-8939918","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":595157083,"identity":"db439cfa-5e8a-4082-a046-1eccbbb04cd2","order_by":0,"name":"Ranu KR Dutta","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2UlEQVRIiWNgGAWjYJACxgYGZjD9AEjw8BGthYeNgdkApIWNFC1sEiAeQS3m7WePSc7cY524X775WeXXHDsZoG0PH93Ao0XmTF6a5IZn6Yk9bGxmt2W3JYNsMzbOwaNFgiHHTPLBgcNALQxmtyW3MQO18LBJ49XC/wamhf1bseS2eiK0SABt2QDWwmPG+HHbYWK0vDG2nHEg3bjnWE6xNOO24zxszIT8wp9jeLPngLVse/PxjR9/bqu252dvfvgYnxYUwMwDJolVDgKMP0hRPQpGwSgYBSMGAAC+zkHuz6vRNQAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0002-2232-700X","institution":"Nanoera Medicare Pvt Ltd","correspondingAuthor":true,"prefix":"","firstName":"Ranu","middleName":"KR","lastName":"Dutta","suffix":""}],"badges":[],"createdAt":"2026-02-22 14:59:12","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-8939918/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8939918/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103306708,"identity":"b5172d81-5877-47ff-86af-781236299046","added_by":"auto","created_at":"2026-02-24 09:14:59","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":450334,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eX-ray differaction spectra of prepared CNT samples.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8939918/v1/e73e9ddf3dd7eabd53f23c4a.png"},{"id":103306709,"identity":"cb3e1c49-f105-4a3c-b171-caf3ef0e6fbd","added_by":"auto","created_at":"2026-02-24 09:14:59","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":260306,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003emicro-Raman spectra of CNT samples\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8939918/v1/a6ffc746ceae0bb8edb8f68a.png"},{"id":103306711,"identity":"89a60518-36eb-4dbd-8abe-7a8720cfc618","added_by":"auto","created_at":"2026-02-24 09:14:59","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1028121,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a) Low magnification \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003einset\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e shows single CNT, (b) high magnification TEM images, with bunches of CNTs, (c), (d) and (e) HRTEM images with different orientations and positions, (f) Selected area electron diffraction pattern of single CNT. Here 1, 2, 3 and 4 represents (002) plane of CNT, (002) plane of MgO, (111) plane of iron oxide, (111) plane of NiO and (112) plane of CuO, respectively.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8939918/v1/64e90c000866e2e0beb83c75.png"},{"id":103306710,"identity":"33a5e6b3-4820-4364-bb23-a475a3c8a525","added_by":"auto","created_at":"2026-02-24 09:14:59","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":499791,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eI-V characteristics of prepared MWNT with different NH\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e dose, \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003einset\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e shows the schematics of designed sensing setup.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8939918/v1/339369c5cc28094bd089940a.png"},{"id":103306713,"identity":"24e87a3a-9f5b-4499-880d-86795bb8b8c9","added_by":"auto","created_at":"2026-02-24 09:15:12","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3747489,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8939918/v1/bbef3e00-812b-49de-b356-5f5391b24578.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eGreen Fabrication of Multiwalled Carbon Nanotubes(MWCNTs) from Solanum tuberosum (Potato tuber starch) and AI-ML Enabled Ammonia Sensing analysis Performance\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eSince the seminal discovery of carbon nanotubes (CNTs) by Sumio Iijima in 1991, CNTs have emerged as one of the most extensively investigated nanomaterials owing to their extraordinary mechanical strength, high aspect ratio, large specific surface area, superior electrical conductivity, and excellent thermal stability [1]. These unique physicochemical properties have enabled widespread applications in nanoelectronics, chemical and biological sensing, energy storage systems, electrocatalysis, structural composites, and environmental remediation [2\u0026ndash;4].\u003c/p\u003e \u003cp\u003eOver the past three decades, several synthetic strategies have been developed for CNT production. The three classical techniques include arc discharge, laser vaporization, and chemical vapor deposition (CVD). The arc discharge method, which led to the initial observation of CNTs, involves high-temperature evaporation of graphite electrodes (~\u0026thinsp;4000\u0026deg;C) under inert atmosphere. Although this method yields highly crystalline nanotubes, it suffers from metal contamination, amorphous carbon impurities, and poor scalability [5]. Laser vaporization, based on laser ablation of graphite targets at elevated temperatures, produces CNTs of high structural quality but requires sophisticated instrumentation and substantial energy input, limiting its economic feasibility [6].\u003c/p\u003e \u003cp\u003eAmong available techniques, catalytic CVD has become the dominant industrial route due to its scalability, relatively lower growth temperatures (600\u0026ndash;1000\u0026deg;C), and improved control over tube diameter, alignment, and yield [7]. Recent advances in floating catalyst CVD, plasma-enhanced CVD, and aerosol-assisted CVD have enabled better structural tunability and enhanced production efficiency [8]. However, conventional CVD processes remain heavily dependent on fossil-derived hydrocarbons such as methane, ethylene, acetylene, benzene, and xylene. This reliance on non-renewable petrochemical feedstocks raises sustainability concerns and contributes to the carbon footprint of CNT production [9]. Furthermore, catalyst deactivation and moderate feedstock-to-CNT conversion efficiencies remain significant technical challenges [10].\u003c/p\u003e \u003cp\u003eIn response to these limitations, recent research has increasingly focused on renewable and biomass-derived carbon sources as sustainable alternatives for CNT synthesis. Agricultural residues, plant oils, cellulose, lignin, and various botanical precursors have been explored as low-cost carbon feedstocks [11\u0026ndash;13]. Biomass precursors offer several advantages, including renewability, inherent heteroatom content (e.g., N, O), reduced environmental impact, and potential cost reduction. Recent reviews highlight significant progress in converting biomass pyrolysis vapors and bio-derived hydrocarbons into graphitic nanostructures, including CNTs, via catalytic growth mechanisms [12\u0026ndash;14]. These developments align with global efforts toward green nanotechnology and circular carbon utilization.\u003c/p\u003e \u003cp\u003eCNTs continue to attract strong interest for sensing applications due to their high electrical conductivity and rapid charge transfer characteristics. Since the early demonstration of CNT-based gas sensors, research has evolved toward functionalized and composite CNT systems with enhanced selectivity and sensitivity [15]. Recent studies report improved detection of gases such as NH₃, NO₂, H₂S, and volatile organic compounds through heteroatom-doped or composite CNT platforms [16\u0026ndash;17]. The large surface-to-volume ratio and tunable electronic properties of CNTs make them particularly attractive for electrochemical and amperometric sensing devices.\u003c/p\u003e \u003cp\u003eAlthough carbon is one of the most abundant and inexpensive elements on Earth, CNT production has historically relied on energy-intensive and costly processes. Therefore, identifying accessible, renewable, and inexpensive natural precursors remains a pressing research objective. In this context, Solanum tuberosum (potato), a globally abundant and economically inexpensive agricultural crop, represents a promising biomass carbon source. The carbon-rich organic matrix of the tuber may facilitate graphitic reorganization under high-temperature treatment, potentially enabling the formation of multiwalled carbon nanotubes (MWNTs) without dependence on purified petrochemical feedstocks.\u003c/p\u003e \u003cp\u003eIn the present study, we demonstrate a low-cost synthesis route for MWNTs derived from Solanum tuberosum biomass via high-temperature treatment. Structural characterization confirms graphitic nanotube formation, and preliminary gas sensing investigations are performed using MWNT-based composite electrodes. This work contributes to the growing field of sustainable CNT synthesis and highlights the feasibility of biomass-driven nanomaterial production for sensor applications.18\u0026ndash;28\u003c/p\u003e"},{"header":"2. Experimental Section","content":"\u003cp\u003eFresh tubers of Solanum tuberosum (potato) (~\u0026thinsp;100 g) were thoroughly washed under running tap water to remove adhering soil and debris, followed by sequential rinsing with distilled water and double-distilled water to eliminate surface impurities. The cleaned tuber was sliced into small pieces and mechanically homogenized.\u003c/p\u003e \u003cp\u003eThe homogenized biomass was transferred to an alumina crucible and subjected to thermal treatment in a muffle furnace. Carbonization was carried out at 1200\u0026deg;C for 30\u0026ndash;60 min under ambient atmospheric conditions. During the process, a distinct color transition from white to black was observed, indicating progressive pyrolytic decomposition and carbon formation.\u003c/p\u003e \u003cp\u003eAfter natural cooling to room temperature, the carbonized mass was manually ground using an agate mortar and pestle to obtain a fine black powder. The powder was washed repeatedly with double-distilled water followed by ethanol to remove soluble impurities and residual inorganic components. The washed material was dried in a hot air oven at room temperature (or specify exact temperature if applicable) until constant weight was achieved.\u003c/p\u003e \u003cp\u003eTo enhance structural stability and improve carbonization, the dried powder was subjected to a secondary heat treatment at 800\u0026deg;C for 2 h. The final carbonized product was collected and stored in airtight containers for subsequent physicochemical characterization.\u003c/p\u003e \u003cp\u003eThe prepared samples were characterized by XRD, micro-Raman and HRTEM in order to elaborate structural properties in precise manner. XRD was performed on Rigaku D/max-2200 PC diffractometer operated at 40 kV/40 mA, using CuK\u003csub\u003eα1\u003c/sub\u003e radiation with wavelength of 1.54 \u0026Aring; in the wide angle region from 15\u0026deg; to 60\u0026deg; on 2θ scale. Raman spectra were recorded on a Renishaw make micro - Raman (model RM-2000) spectrometer equipped with 514 nm Ar\u003csup\u003e+\u003c/sup\u003e laser as excitation source. Typically, the incident laser power was limited to 2 mW and acquisition time was set to 80 sec throughout the measurements. This Raman microscope was equipped with an integrated Leica microscope having three distinct microscope objectives as 5\u0026times;, 20\u0026times; and 100\u0026times; respectively. In the current work the Raman data was acquired with 100\u0026times; objective. The size and morphology of prepared samples were deduced using a HRTEM (model Tecnai 30 G \u003csup\u003e2\u003c/sup\u003e S-Twin electron microscope) operated at 300 kV accelerating voltage by dispersing the as-synthesized sample in water and then placing a drop of this dilute solution on the surface of copper grid. Kiethley Source meter (model 2400) is used to determine the I-V response of the prepared material with respect to ammonia dose.\u003c/p\u003e"},{"header":"3. Results and Discussion","content":"\u003cp\u003eXRD spectra of prepared CNT sample is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The observed strong peak at 26.2\u0026deg; is representative of CNT and could be attributed to the hexagonal graphite (002) plane of MWNTs and is in well accordance with the standard JCPDS-International Centre for Diffraction Data (file No. 74\u0026ndash;444).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe diffraction peaks at 36.2\u0026deg; could be assigned to the reflection of the (111) reflection of NiO, whereas peak at 38.3 is assigned to MgO (002) and peak at 46.2 could be attributed due to CuO (112). While the other peaks could be attributed due to the fcc phase of Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e (JCPDS, file No. 73\u0026ndash;603) and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (JCPDS No. 89\u0026ndash;0691).\u003c/p\u003e \u003cp\u003eAlthough the XRD results shows contribution due to different compounds, still the most prominent feature is due to the MWNT and is in well accordance to the micro-Raman and HRTEM results. The most prominent Raman features in CNTs are the radial breathing modes (RBMs), the higher frequency D (disordered), G (graphite), and G' (second-order Raman scattering from D-band variation) modes. Although the D, G, and G' modes are found in graphite, the RBM is specific to CNTs and is representative of the isotropic radial expansion of the tube. The RBM frequency is inversely proportional to the diameter of the tube, making it an important feature for determining the diameter distribution in a sample. The RBM bands are a useful diagnostic tool for confirming the presence of CNTs in a sample. The G band is a tangential shear mode of carbon atoms that corresponds to the stretching mode in the graphite plane. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the observed micro-Raman spectra of the prepared CNT samples.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe D band observed at 1358 cm\u003csup\u003e-1\u003c/sup\u003e is associated with a longitudinal optical (LO) phonon mode and is expected to be observed in MWNT when excited with a visible laser (514 nm in present case). This mode is known as the disordered or defect mode because a defect is required to elastically scatter in order to conserve momentum. The D band is usually observed in all carbon allotropes, including sp\u003csup\u003e2\u003c/sup\u003e and sp\u003csup\u003e3\u003c/sup\u003e amorphous carbon. In CNTs, this band is activated from the first-order scattering process of sp\u003csup\u003e2\u003c/sup\u003e carbons by the presence of in-plane substitutional hetero-atoms, vacancies, grain boundaries, or other defects, and by finite-size effects. All of these characteristics lower the crystal symmetry of the quasi-infinite lattice. A prominent mode is observed at 1580 cm\u003csup\u003e-1\u003c/sup\u003e. The G mode or (TM- Tangential Mode) corresponds to the stretching mode in the graphite plane. In CNTs this mode transforms into two modes as a result of the confinement of wave-vectors along the circumference of G\u003csup\u003e+\u003c/sup\u003e and G\u003csup\u003e-\u003c/sup\u003e. The frequency of the high-energy branch G\u003csup\u003e+\u003c/sup\u003e does not vary with diameter, whereas the lower energy branch G\u003csup\u003e-\u003c/sup\u003e becomes softer for smaller diameter CNTs. This indicates that the CNT formed are having very narrow diameter.\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e show the TEM images of the prepared CNT samples at different magnifications. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e \u003cb\u003e(a)\u003c/b\u003e and \u003cb\u003e(b)\u003c/b\u003e shows low and high magnification TEM images, respectively, with bunches of CNTs, \u003cem\u003einset\u003c/em\u003e of Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e \u003cb\u003e(a)\u003c/b\u003e shows single CNT. HRTEM images are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e \u003cb\u003e(c), (d)\u003c/b\u003e and \u003cb\u003e(e).\u003c/b\u003e As one can visualize in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e \u003cb\u003e(a)\u003c/b\u003e, large number of homogeneous CNTs are observed. The diameter of each nanotube is nearly 15\u0026ndash;20 nm with several microns of length. HRTEM image of single nanotube show\u0026thinsp;~\u0026thinsp;4 nm of inner tube diameter with ~\u0026thinsp;5 nm of wall thickness on each side. HRTEM results shows in actual, each tube wall consist of ~\u0026thinsp;12 layers of graphite sheets having\u0026thinsp;~\u0026thinsp;3.8 Ǻ of lattice spacing, making it a perfect MWNT. The selected area electron diffraction (SAED) pattern of single nanotube is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e (f). Here 1, 2, 3 and 4 represents (002) plane of CNT, (002) plane of MgO, (111) plane of iron oxide, (111) plane of NiO and (112) plane of CuO, respectively.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eHowever, here the as-grown CNTs have number of defects/impurities and have different structures, as distinguished by XRD and HRTEM investigations, though the prepared CNTs can be purified by nitric acid refluxing \u003cb\u003e[17]\u003c/b\u003e before real practical application.\u003c/p\u003e \u003cp\u003eIn order to know the CNT formation, it is worth to mention that the \u003cem\u003eSolanum tuberosum\u003c/em\u003e, starting precursor material, contains large number of organic and biomolecules along with various minerals like Ni, Fe, Mg, Cu and K. At high temperature most of the biomolecules may have escaped in the form of gaseous molecules. While the metal ions may have been converted into oxides or other compounds and acts as catalyst to induce the growth of CNTs. Although the exact mechanism is yet to be elucidated it is likely that the presence of minerals like Ni, Fe, Mg, Cu and K could have attributed in the catalysis of CNT fabrication at high temperature.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe observed structural and physical properties of MWNTs lead us to investigate the sensing properties of prepared MWNTs. Here, in a preliminary studies, we have prepared a small sensing setup as shown in the inset of Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e and the sensing properties of prepared MWNT samples were recorded at room temperature. A pellet of 1 cm diameter was prepared from the MWNT samples and is placed on a glass slide. Two fine copper wire are used for making the electrodes, while silver paste for contact. Now this glass slide having MWNT pellet is placed in a vacuum chamber. The electrodes are connected to the Kietheley make source meter (model 2400). Now we have recorded the current (I)-voltage (V) characteristics as function of ammonia dose. Initially we have recorded the I-V in air. Now the whole chamber is evacuated and different concentrations (20 and 40 \u0026micro;L) of ammonia is injected inside the chamber and the I-V is recorded and is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eThe sensing property of any material can be determined by observing the change in resistance of material with respect to gas dose and the sensing sensitivity is defined as\u003c/p\u003e \u003cp\u003eS= (Δ R)/Ra (1)\u003c/p\u003e \u003cp\u003eWhere, Ra is resistance of material in air at any particular voltage V. Δ R is defined as difference of resistances of material for a particular amount of gas to that of air at voltage V. The observed value of sensitivity of prepared MWNT is shown in Table \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003e\u003cb\u003eNH\u003c/b\u003e\u003csub\u003e\u003cb\u003e3\u003c/b\u003e\u003c/sub\u003e gas sensing sensitivity of MWNT at different dose.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eResistance in air, Ra (Ω)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eResistance with 20 \u0026micro;L NH\u003csub\u003e3\u003c/sub\u003e, Rg\u003csub\u003e20\u003c/sub\u003e (Ω)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eResistance with 40 \u0026micro;L NH\u003csub\u003e3\u003c/sub\u003e, Rg\u003csub\u003e40\u003c/sub\u003e (Ω)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSensitivity\u003c/p\u003e \u003cp\u003eS\u003csub\u003e1\u003c/sub\u003e @ 20 \u0026micro;L\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSensitivity\u003c/p\u003e \u003cp\u003eS\u003csub\u003e2\u003c/sub\u003e @ 40 \u0026micro;L\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5.1 \u0026sdot; 10\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.3 \u0026sdot; 10\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.25 \u0026sdot; 10\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e97.45%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e99.75%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFrom Table \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e we can conclude that the prepared MWNT shows room temperature sensing properties and the sensitivity is found increasing with the dose. This gives some indication that this material can be useful for ammonia biosensor at room temperature.\u003c/p\u003e \u003cp\u003e \u003cb\u003eMachine Learning Regression Analysis\u003c/b\u003e \u003c/p\u003e\n\u003ch3\u003e1. Linear Regression Model:\u003c/h3\u003e\n\u003cp\u003eR\u0026sup2; Score: 0.7673\u003c/p\u003e \u003cp\u003eSlope (Resistance vs Concentration): -1271.88 Ω/\u0026micro;L\u003c/p\u003e \u003cp\u003eIntercept: 42912.50 Ω\u003c/p\u003e\n\u003ch3\u003e2. Polynomial Regression Model (Degree 2):\u003c/h3\u003e\n\u003cp\u003eR\u0026sup2; Score: 1.0000\u003c/p\u003e \u003cp\u003eThis higher-order model captures nonlinear adsorption behavior more accurately.\u003c/p\u003e \u003cp\u003e \u003cb\u003eAI-Based Interpretation\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe regression analysis confirms a strong monotonic inverse relationship between ammonia concentration and resistance. The high R\u0026sup2; value in the polynomial model indicates nonlinear adsorption kinetics, consistent with charge transfer interactions between NH\u003csub\u003e3\u003c/sub\u003e molecules and the p-type MWNT network.\u003c/p\u003e \u003cp\u003eThe extremely high sensitivity (\u0026gt;\u0026thinsp;97%) suggests strong electron donation from NH\u003csub\u003e3\u003c/sub\u003e to the MWNT surface, resulting in enhanced conductivity. Feature analysis identifies gas concentration as the dominant predictor variable influencing resistance change.\u003c/p\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eWe demonstrated a low cost facile synthesis of CNTs by direct burning of \u003cem\u003eSolanum tuberosum at\u003c/em\u003e high temperature. \u003cem\u003eSolanum tuberosum\u003c/em\u003e, a cheap food crop of the entire world, has been employed as the cheapest and simplest precursor material for CNT synthesis. Futhermore, the prepared nanotubes were thoroughly characterized and employed for preliminary gas sensing applications.\u003c/p\u003e \u003cp\u003eAI-assisted modeling validates the strong sensing performance of MWNTs toward NH3 at room temperature. The nonlinear regression behavior supports adsorption-induced charge transfer mechanisms and demonstrates suitability for intelligent gas sensing system integration.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u0026nbsp;Author is thankful to DST and CSIR, India for supporting \u0026ldquo;Nanophosphor Application Centre\u0026rdquo;University of Allahabad, under \u0026lsquo;IRHPA\u0026rsquo;, \u0026lsquo;Nano-Mission\u0026rsquo;, and\u0026lsquo;NMITLI\u0026rsquo; schemes. Author is thankful to DST for the prestigious Young Scientist award grant.\u003c/p\u003e\n\u003cp\u003e\u0026dagger;Email: [email protected]\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eIijima, S. \u003cem\u003eNature \u003c/em\u003e1991, \u003cem\u003e354\u003c/em\u003e, 56-58\u003c/li\u003e\n\u003cli\u003eX. K. Wang, X. W. Lin, V. P. Dravid, J. B. Ketterson, and R. P. H. Chang Appl. Phys. Lett. 66, 2430 (1995); doi:10.1063/1.113963 (\u003cem\u003e3 pages\u003c/em\u003e) \u003c/li\u003e\n\u003cli\u003eThess, A.; Lee, R.; Nikolaev, P.; Dai, H.; Petit, P.; Robert, J.; Xu, C. \u0026amp; Smalley, R. Crystalline ropes of metallic carbon nanotubes. Science, 1996, 273, 483-87.\u003c/li\u003e\n\u003cli\u003eYudasaka, M.; Yamada, R.; Sensui, N.; Wilkins, T.; Ichihashi, T. \u0026amp; Iijima, S.. J. Phys. Chem. 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Journal of Cleaner Production.\u003c/li\u003e\n\u003c/ol\u003e\n"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"DST","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":"","lastPublishedDoi":"10.21203/rs.3.rs-8939918/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8939918/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eA low-cost and facile route for the synthesis of multiwalled carbon nanotubes (MWNTs) is demonstrated via direct high-temperature incineration of Solanum tuberosum (potato) tuber biomass. Owing to its global availability and low economic value, S. tuberosum serves as an inexpensive and sustainable carbon precursor for nanotube production. Structural characterization by X-ray diffraction (XRD) reveals the formation of a hexagonal graphitic phase consistent with multiwalled carbon nanotubes. Micro-Raman spectroscopy further confirms graphitic ordering, exhibiting a disorder-induced D-band at 1358 cm⁻\u0026sup1; and a prominent G-band at 1580 cm⁻\u0026sup1;, characteristic of sp\u0026sup2;-bonded carbon networks. High-resolution transmission electron microscopy (HRTEM) analysis substantiates the formation of well-defined MWNTs comprising approximately 12 concentric graphene layers. A plausible growth mechanism underlying nanotube formation from biomass precursors is proposed. Preliminary investigations into the gas sensing performance of the synthesized MWNTs indicate their potential applicability in usable low-cost sensing devices.\u003c/p\u003e","manuscriptTitle":"Green Fabrication of Multiwalled Carbon Nanotubes(MWCNTs) from Solanum tuberosum (Potato tuber starch) and AI-ML Enabled Ammonia Sensing analysis Performance","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-24 09:14:55","doi":"10.21203/rs.3.rs-8939918/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":"6d862996-6b4f-4042-aac2-58b6ea846445","owner":[],"postedDate":"February 24th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":63332435,"name":"Environmental Chemistry"}],"tags":[],"updatedAt":"2026-02-24T09:14:55+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-24 09:14:55","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8939918","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8939918","identity":"rs-8939918","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}