The controllable assembly of the heterojunction interface of the ZnO@rGO for enhancing the sensing performance of NO2 at room temperature and sensing mechanism

Abstract

ZnO@the reduced graphene oxide (rGO) nanorod arrays were grown in-situ on the ceramic tube substrate by one-step hydrothermal without any template or surfactant. The reduced graphene oxide was evenly coated around the ZnO nanorods through the controllable assembly of the rGO and ZnO heterojunction interface. rGO contributed to the improvement of material conductivity and provided more active sites to adsorb NO2 molecules. The combination of rGO and ZnO significantly enhanced the response of the composite to NO2 at room temperature. It showed an excellent selectivity to NO2 and a good linear relationship in the concentration range of 0.1∼10 ppm. In order to explore the response mechanism of ZnO@rGO composite to NO2, the change of element composition and status was performed by XPS technology before and after the exposure of the composite to NO2. The gaseous products after the reaction were also tested by GC–MS technology. DFT calculations were performed based on the test results, which demonstrated that the p-n heterostructure produced by the ZnO@rGO composite had a beneficial effect on improving the gas response capability.