▎ 摘　　要

Here, we demonstrate the improved NO2 gas-sensing properties based on graphene-decorated NiS2 thin film. The grown NiS2 thin film, graphene was spread over NiS2 thin film by chemical vapour deposition (CVD) method. The formation of several p-n heterojunctions is greatly affected by the current-voltage relation of graphene-decorated NiS2 thin film due to p-type and n-type nature of graphene and NiS2, respectively. Initially with graphene decoration on NiS2 thin film, current decreases in comparison to NiS2 thin film, whereas depositing graphene film on glass substrate, current increases drastically. The NO2 gas sensor device is fabricated and its basic characteristics are systematically investigated. The incorporated graphene improves the NO2 sensing response of 97% with compared to bare NiS2 sensor (29%) at 100 ppm NO2 concentration with a practical detection limit below 0.2 ppm. In addition, the recovery time was shortened to a few seconds and the excellent repeatability. This work may provide a promising and practical method to mass produce room-temperature NO2 gas sensors for real-time environment monitoring due to its simple fabrication process, low cost, and practicality. The high-sensing response of NiS2/graphene is attributed to the formation and modulation of p-n heterojunction at the interface of graphene and NiS2. In addition, the presence of active sites graphene surface also enhances the sensing response.