Ternary SnO2/Fe2O3/RGO composite: Microwave-assisted preparation and its high H2S-sensing performance

Abstract

A SnO2/α-Fe2O3 nanoparticle modified reduced graphene oxide nanosheets (SnO2/Fe2O3/RGO) composite was synthesized via a two-step microwave-assisted method based on graphene oxide. SnO2/α-Fe2O3 nanoparticles with particle sizes of 11-43 nm were formed on the surfaces of the RGO. SnO2 nanoparticles are uniformly dispersed on α-Fe2O3 surfaces with a mean particle size of approximately 5 nm. By adjusting the molar ratio of SnO2 to α-Fe2O3, the gas-sensing properties of the obtained SnO2/Fe2O3/RGO composite were studied, focusing on its response and selectivity to H2S gas at low temperatures. The results indicate that the 3-SnO2/Fe2O3/RGO sensor has the highest sensitivity, ultrafast response, and excellent selectivity to 1-25 ppm H2S gas at 180°C, achieving a response of up to 31 to 25 ppm H2S with a response time of only 4 seconds. Moreover, the sensor shows good selectivity and long-term stability. To other 100 ppm gases, the responses of the 3-SnO2/Fe2O3/RGO sensor are no more than 5 at 180°C. The enhanced H2S sensing performance of the SnO2/Fe2O3/RGO sensor should be attributed to the abundant oxygen vacancies, n-n heterojunctions, and p-n heterojunctions in the SnO2/Fe2O3/RGO composite with a unique hierarchical structure.