Low-Power Optoelectronic NO₂ Sensors by Constructing ZnS/SnS₂ Heterojunctions

The realization of gas sensing at room temperature with zero power consumption has been challenging for semiconductor gas sensors. In this work, an optoelectronic gas sensor based on ZnS/SnS2 heterojunction materials synthesized by the hydrothermal method is reported, and its response to NO2 gas at room temperature (25 °C) is systematically studied. The results show that the ZnS/SnS2 heterojunction facilitates effective charge transfer, increases surface adsorption sites, and significantly enhances the sensing performance, especially when the ratio of ZnS to SnS2 is 1:1, and the response value to 10 ppm of NO2 under ultraviolet irradiation is as high as 160, showing excellent sensitivity. The improved performance is primarily attributed to optimized surface properties and accelerated electron transfer at the heterojunction interface, which collectively enhance the NO2 adsorption and desorption processes. Our results demonstrate that, by adjusting the composition of heterojunction materials, their gas-sensing properties can be effectively tuned, providing a promising strategy for the development of high-performance gas sensors.