In-situ growth of ZnO@ZnWO4 heterojunction with flower-like structure by chemical vapor deposition for H2S gas sensor

The detection of hydrogen sulfide (H 2 S) plays a critical role in environmental monitoring and breath analysis for medical diagnostics. For metal oxide semiconductor film-based gas sensors, the quality of the gas-sensitive material and the method of forming the gas-sensitive film on planar electrodes are critical determinants of sensor performance. In this study, a flower-like ZnO@ZnWO 4 heterojunction was directly grown on the surface of a micro-hotplate for gas sensor applications using a two-step method involving block copolymer self-assembly and chemical vapor deposition. The gas sensors demonstrated exceptional performance in detecting H 2 S over a range of 50 ppb to 50 ppm. At an operating temperature of 200 °C, the gas sensor exhibited a remarkable response value (R=127.31) for 5 ppm H 2 S and an outstanding selectivity coefficient of 117.4. Additionally, the sensor maintained 95 % of its original response value over a month. These superior performance metrics are attributed to the n-n heterostructure between ZnO and ZnWO 4 , along with the extensive specific surface area and the presence of oxygen vacancies in the flower-like morphology. This novel approach not only enhances H 2 S detection performance but also significantly contributes to the development of gas sensors crucial for environmental monitoring and human health protection.