Synthesis of CuO/ZnWO4 Heterojunction Structure for H2S Gas Sensor with Ultra-High Response Value at Room Temperature

H2S detection is critical for personal and industrial safety. Generally, metal oxide-based H2S sensors exhibit no response at room temperature (RT). In this study, CuO/ZnWO4 (C-ZWO) nanocomposites were prepared via a two-step hydrothermal process and applied to RT H2S sensing. The results show that the C-ZWO sensors exhibit an elevated response value at RT and balanced gas-sensing properties at 100 °C. Significantly, the response value of a 10% C-ZWO sensor to 25 ppm of H2S at RT is 651.6 with a response time of 78 s, which is 310.3 times that of the ZnWO4 sensor (2.1). The systemic characterization results suggest that the enhanced RT H2S-sensing properties are ascribed to the synergistic effects of the growth-specific surface area and oxygen vacancy occupancy, the enhanced oxygen reduction ability, and the formation of the p–n heterojunction structure between CuO and ZnWO4. The C-ZWO nanocomposites possess added active sites for H2S adsorption and dissociation, with the p–n heterojunction giving rise to higher electrical resistance, and thus, the follow-up produces a high response value even at RT.