OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 27 No. 3 2025 for various environments [5]. Another study showcases the efficacy of using encapsulated ionic liquids in nanostructured frameworks for enhanced humidity sensing capabilities, reinforcing the trend of leveraging novel materials for improved performance [6]. Self-powered and biocompatible sensors are increasingly under research, and graphene oxide-based humidity sensors promise energy-efficient, sensitive detection [7]. An rGO:MoS₂-based temperature-integrated humidity sensor proves the versatility of its applications in reality [8]. Research investigating TiO2-SnS2 heterostructures for use in humidity sensors emphasizes the advantages of nanoarchitectures in enhancing sensor performance [9‑12]. Metal oxide humidity sensors, like ZnO, TiO₂, and SnO₂, are commonly researched for their stability and moisture sensitivity and measure humidity through capacitance or resistance changes after water adsorption [1‑3]. These characteristics make ZnO an exceptionally versatile material for fabricating high-performance humidity sensors. Furthermore, the tunable electronic properties of ZnO, achieved through doping with various elements and precise nanostructuring, allow for fine-tuning of the sensor’s performance to meet specific application requirements [13‑14]. Nanographite material (NGM), which is green synthesized from orange and lemon peels, improves ZnO-based humidity sensors with enhanced charge transfer, adsorption ability, and stability, thereby supporting sustainable nanotechnology [10]. Recent studies emphasize the need for improvements in response times and recovery cycles in humidity sensors, highlighting that these parameters are critical for effective real-time applications [15‑16]. A study conducted by Ullah et al. demonstrated that by integrating nanographite with metal oxides, the resulting sensor achieved significant reductions in response and recovery times, addressing previous limitations [17]. Furthermore, research by Chaudhary et al. emphasized the importance of utilizing innovative architectures and materials to enhance the sensor’s overall performance metrics [18]. Moreover, the study by Li et al. outlined the effectiveness of doping ZnO with nanographite in improving the sensor’s performance at various humidity levels, showcasing its potential for practical application [13]. The tunability of electronic properties through the introduction of nanographite provides researchers with new avenues for enhancing sensor reliability and efficiency, making them more suitable for integration into IoT and smart technology frameworks [14]. Despite the aforementioned studies, there is still a need for enhancement of zinc oxidebased nanosensors for lower response times. Despite these advancements, there is still a clear need to develop ZnO-based humidity sensors with lower response times, improved stability, and environmentally friendly, scalable fabrication techniques. Specifically, the integration of NGM into ZnO using cost-effective and simple chemical methods remains relatively underexplored. The present work aims to address these limitations by synthesizing ZnO–NGM nanocomposites via a low-cost chemical precipitation method. The nanocomposites are deposited onto fluorine-doped tin oxide (FTO) substrates using the doctor-blade technique to fabricate capacitive-type humidity sensors. The use of NGM is expected to improve the sensor’s performance by enhancing electrical conductivity and water molecule interaction at the surface. Comprehensive characterization, including UV–Vis spectroscopy, SEM, XRD, and FTIR, was conducted to analyze the structural, optical, and chemical features of the material. Humidity sensing was evaluated through capacitance and impedance analysis in a nitrogen-controlled environment across RH levels from 10% to 95% [19]. Capacitance and impedance measurements assessed the humidity sensing capability of these synthesized sensors. The results contribute to the development of improved humidity nanosensors, with implications for environmental monitoring, healthcare, and industrial automation. Investigation techniques Materials and Methods High-purity analytical-grade zinc acetate (Zn(CH₃COO)₂), ammonium hydrogen carbonate (NH₄HCO₃), nanographite material (NGM), ethanol (analytical grade), and ethyl cellulose were sourced from BDH, Merck, and Sigma-Aldrich. Deionized water was employed throughout the synthesis and washing to avoid ionic or particulate contamination. Fluorine-doped tin oxide (FTO) glass substrates were employed for
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