▎ 摘　　要

In this paper, we prepared reduced graphene oxide (RGO) thin film by simple airbrush technology and then studied its gas-sensing behaviors at room temperature. On exposure to dynamic NO2 gas, RGO thin film showed a time-resolved n-p transition process (n-type switched to p-type), due to its weak n-type properties arising from hydrazine-reduction method and strong electron-accepting NO2 molecules. As RGO amount was added, the time taken to run through this transition became longer. On consecutive exposures to NO2 and NH3 gases, p-n transition (p-type switched to n-type) emerged as well. To suppress these transition behaviors, CuCl was incorporated into RGO material, resulting in opposite p-type characteristics for the composite film as well as no occurrence of p-n transition during the sensing tests. Compared to pure RGO counterpart, RGO/CuCl film had a six-fold response enhancement and a likewise good repeatability toward 10 ppm NH3 within four cyclic periods. We expect that the proposed research on transition behaviors and relevant suppression methods will shed new light on gas-sensing mechanisms and improve operation stability of RGO based sensors.