Microwave-Assisted Hydrothermal/Impregnation Synthesis of Cu2O-Decorated rGO/In2O3 Nanorices for Sensitive SO2 Gas Sensors

In the present development, Cu2O-decorated reduced graphene oxide/indium oxide (rGO/In2O3) nanorices with Cu contents of 0–1.5 wt % were synthesized by a microwave-assisted hydrothermal method combined with impregnation and studied for gas-sensing applications toward SO2. The material characterization results revealed that 3–5 nm Cu2O secondary nanoparticles were uniformly decorated on porous In2O3 nanorices mixed with rGO sheets. Based on systematic gas-sensing measurements, Cu2O decoration on rGO/In2O3 nanorices with the optimal Cu content of 1.0 wt % provided a considerably improved SO2 response of 11.1 to 5 ppm SO2, which was approximately 3.3-fold as high as that of pristine rGO/In2O3 nanorices (3.4) at an optimal temperature of 200 °C. Additionally, high SO2 selectivity was attained against NO2, NO, CO, H2S, C2H5OH, C2H4, H2, and NH3. Moreover, the Cu2O-rGO/In2O3 sensors displayed low humidity sensitivity, good repeatability, and satisfactory long-term stability. Therefore, Cu2O-decorated rGO/In2O3 nanorices represented one of the most promising SO2 sensors for environmental and practical applications.