Three-dimensional Au nanoparticles-decorated ?-Fe2O3@reduced graphene oxide core-shell heterojunctions for highly sensitive room-temperature gas sensors

Au nanoparticles (Au NPs)-decorated three-dimensional (3D) reduced graphene oxide (RGO)-wrapped gamma-Fe2O3 nanospheres (gamma-Fe2O3@RGO) heterojunctions have been synthesized via a combination of self-assembly and in-suit ultrasound-induced decoration method. The Au NPs-decorated gamma-Fe2O3@RGO (gamma-Fe2O3@RGO-Au) hetero-junctions sensor exhibits an excellent response of 384% to 50 ppm NO2 at room temperature, which is enhanced compared to the sensors based on bare RGO (35%) and gamma-Fe2O3@RGO (243%). Furthermore, the calculation based on density functional theory (DFT) has been used to simulate the interaction between NO2 gas and sensing materials, thereby providing a theoretical basis for our experimental results. Moreover, the enhanced gas-sensing properties of gamma-Fe2O3@RGO-Au have been explained by combing the 3D structure, the as-formed heterojunctions with chemical and electronic effect of Au NPs. Our results demonstrate an effective strategy for designing high performance RGO-based sensors based on 3D core-shell heterojunctions.