▎ 摘　　要

gamma-Fe2O3 as an excellent materials has been extensively used in gas-sensing. However, the gamma-Fe2O3 gas-sensors demands for high working temperatures and shows poor selectivity. In this work, we developed a high-sensitive gamma-Fe2O3/rGO gas-sensor for H2S at room temperature. gamma-Fe2O3/rGO composite was formed by highly dispersed gamma-Fe2O3 octahedrons derived from MIL-88 on reduced graphene oxide (rGO). Compared with the bare gamma-Fe2O3 sensor, the arranged gamma-Fe2O3/rGO composites sensors had enhanced gas-sensing performance evidently for H2S. It was noted that the optimized gamma-Fe2O3/rGO composite embraces unparalleled sensitivity for H2S (R-air/R-gas = 520.73, 97 ppm) but few responses to NH3, CHCl3, NO, SO2 and HCHO. gamma-Fe2O3 realizes gas detection based on the bulk resistance effect, while the gas-sensitive detection mechanism of the rGO composites was dominated by the surface-controlled type. The outstanding H2S sensing performance of gamma-Fe2O3/rGO composites sensors was attributed to the excellent conductivity and abundant active sites of two-dimensional rGO. These results provide a method that can effectively enhance the gas sensor performance of MOF-derived metal oxide semiconductors.