OBRABOTKAMETALLOV Vol. 27 No. 3 2025 201 MATERIAL SCIENCE Fabrication, characterization and performance evaluation of zinc oxide doped nanographite material as a humidity sensor Farrukh Waheed 1, a, Amtul Qayoom 2, b, Muhammad Faizan Shirazi 3, c, * 1 Department of Computer Science, Usman Institute of Technology University, ST-13, Abul Hasan Isphahani Road, Block 7, Gulshan-e-Iqbal, Karachi, 75300, Pakistan 2 Department of Chemistry, NED University of Engineering and Technology, University Road, Karachi, 75270, Pakistan 3 Department of Electronic Engineering, NED University of Engineering and Technology, University Road, Karachi, 75270, Pakistan a https://orcid.org/0009-0004-6527-0965, fwbaig@uitu.edu.pk; b https://orcid.org/0000-0003-0149-2177, amtulq@neduet.edu.pk; c https://orcid.org/0000-0002-4488-8860, faizanshirazi@neduet.edu.pk Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2025 vol. 27 no. 3 pp. 183–204 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2025-27.3-183-204 ART I CLE I NFO Article history: Received: 04 June 2025 Revised: 23 June 2025 Accepted: 10 July 2025 Available online: 15 September 2025 Keywords: Humidity sensor ZnO nanoparticles Smart sensing Devices Capacitance and impedance analysis Fast response and recovery Environmental and industrial monitoring Funding The work is carried out within the framework of the NEDUET PhD program. ABSTRACT Introduction. The growing demand for real-time environmental monitoring technologies has led to increased interest in high-performance humidity sensors with rapid response, high sensitivity, and long-term stability. Zinc oxide (ZnO) is a widely used semiconducting oxide material for such applications due to its chemical stability and sensitivity to humidity variations. However, its performance can be further enhanced through material engineering. This study investigates the doping of ZnO nanoparticles with nanographite material (NGM) to improve humidity-sensing characteristics. The purpose of the work is to develop ZnO–NGM nanocomposite-based capacitive humidity sensors with improved response/recovery time and sensitivity by modifying the electronic and surface properties of ZnO through NGM doping. Research methods. ZnO–NGM nanocomposites with varying NGM content (1 wt.%, 2 wt.%, 4 wt.%, 5 wt.%, and 10 wt.%) were synthesized via a chemical precipitation route. The optical behavior of pure ZnO was analyzed using UV–Vis spectroscopy, which revealed a sharp absorption edge at 367 nm, indicating a bandgap near 3.3 eV. Structural and morphological properties were examined using X-ray diff raction (XRD) and scanning electron microscopy (SEM), confi rming NGM integration and enhanced surface porosity. The composite sensing fi lms were deposited onto FTO-coated glass substrates using the ‘doctor blade’ method to fabricate the capacitive sensors. The sensing performance was evaluated in a nitrogen-controlled chamber over a relative humidity (RH) range of 10% to 95%, with capacitance measurements recorded across a frequency range of 10 kHz to 1 MHz. Results and discussion. Among all tested compositions, the 4 wt.% NGM-doped ZnO sensor demonstrated the best performance, with a rapid response time of 4.0 s, a recovery time of 6.2 s, and excellent sensitivity. These improvements are attributed to enhanced surface conductivity and more active adsorption-desorption kinetics due to NGM. The developed sensors show strong potential for integration in real-time environmental monitoring systems, industrial automation, and smart home humidity control applications. The incorporation of nanographite into ZnO matrices signifi cantly enhances humidity-sensing capabilities. The ZnO–NGM composite, particularly at 4 wt.% doping, off ers a promising pathway for the development of next-generation, high-effi ciency humidity sensors. For citation: Waheed F., QayoomA., Shirazi M.F. Fabrication, characterization and performance evaluation of zinc oxide doped nanographite material as a humidity sensor. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2025, vol. 27, no. 3, pp. 183–204. DOI: 10.17212/1994-6309-2025-27.3-183-204. (In Russian). ______ * Corresponding author Shirazi Muhammad Faizan, Ph.D. (Engineering) Department of Electronic Engineering, NED University of Engineering and Technology, 75270, University Road, Karachi, Pakistan Tel.: +92-21-99261261-8 ext. 2215, e-mail: faizanshirazi@neduet.edu.pk References 1. Saqib M., Ali Khan S., Mutee Ur Rehman H.M., Yang Y., Kim S., Rehman M.M., Young Kim W. Highperformance humidity sensor based on the graphene fl ower/zinc oxide composite. Nanomaterials, 2021, vol. 11 (1), p. 242. DOI: 10.3390/nano11010242. 2. Yang H., Ye Q., Zeng R., Zhang J., Yue L., Xu M., Qiu Z.-J., Wu D. Stable and fast-response capacitive humidity sensors based on a ZnO nanopowder/PVP-RGO multilayer. Sensors, 2017, vol. 17 (10), p. 2415. DOI: 10.3390/ s17102415.
RkJQdWJsaXNoZXIy MTk0ODM1