ZnS modified ZnO nano-heterojunction for efficient trace H2S gas detection

Abstract

ZnO nanowires (NWs), with 200nm diameter, are synthesized by a hydrothermal method and in situ grown on the surface of a micro-sensor for detecting trace H2S gas. A chemical conversion of ZnO to ZnS is adapted to create a ZnS shell over single crystalline ZnO nanowires. The morphology and composition of both ZnO nanowires and ZnO-ZnS core-shell heterojunction are characterized and analyzed using SEM and EDS imaging. Experimental sensing results show that the core-shell geometry results in minimization of the band gap, therefore causing an improvement of sensitivity to H2S gas. At 10ppm H2S gas atmosphere, the response of ZnO-ZnS core-shell nano-heterojunction is 0.67, significantly higher than pure ZnO NWs (0.28). Therefore, modifying ZnO to form ZnO-ZnS nano-heterojunction is an effective method to improve ZnO sensor sensitivity to H2S gas.