eng Oriental Scientific Publishing Company Material Science Research India 0973-3469 2026-05-21 23 1 24096 article Vaishali Tanaji Salunke 1 Vikas Vasant Deshmane 2 Umesh Jagannath Tupe 3 Sajid Naeem 4 Arun Vitthal Patil 5 Department of Electronic Science, MGV’s LVH Arts, Science and Commerce College, Savitribai Phule Pune University, Nashik, Maharashtra, India Department of Physics, SICES Degree College of Arts, Science and Commerce, University of Mumbai, Ambarnath, Maharashtra, India Department of Electronic Science, Vidya-Amrut Dnyan Pratishthan's Arts, Science and Commerce College, Savitribai Phule Pune University, Shirsondi, Maharashtra, India Department of Applied Sciences, Maulana Mukhtar Ahmad Nadvi Technical Campus, Savitribai Phule Pune University, Malegaon, Maharashtra, India Department of Physics, MGV’s Arts, Science and Commerce College, Savitribai Phule Pune University, Manmad, Maharashtra, India ZnO–CuO heterojunction thick films were developed via a screen-printing approach and systematically evaluated for low-temperature methane sensing. The formation of a p–n heterojunction between n-type ZnO and p-type CuO significantly modulates charge transport and surface reactivity. Structural analysis confirmed the coexistence of hexagonal ZnO and monoclinic CuO phases, while microstructural studies revealed a porous and well-connected morphology favorable for gas adsorption. Among all compositions, the 5 wt.% CuO–ZnO film exhibited the smallest crystallite size (~44 nm), higher defect density, and enhanced surface activity, leading to improved electronic properties with optimized resistivity and reduced activation energy. Gas sensing results demonstrated a maximum sensitivity of 94.98% toward CH₄ at a low operating temperature of 60 °C (500 ppm), along with fast response and recovery times (8 s/37 s), excellent selectivity, and long-term stability. The superior performance is attributed to the synergistic effects of increased oxygen vacancies, efficient charge transfer across the ZnO–CuO interface, and enhanced modulation of the depletion layer. These findings establish ZnO–CuO heterojunction thick films as promising candidates for energy-efficient methane sensing applications. https://www.materialsciencejournal.org/vol23no1/high-performance-zno-cuo-heterojunction-thick-films-for-low-temperature-methane-sensing/ Material Engineering Material Science Methane Sensing Screen-Printing Thick Films ZnO-CuO Heterojunction