Effects of reduced graphene oxide loading on gas-sensing characteristics of flame-made Bi2WO6 nanoparticles

In this study, the effects of reduced graphene oxide (rGO) loading on the gas-sensing characteristics of flame-made Bi2WO6 nanoparticles were systematically investigated. Bi2WO6 nanoparticles produced by flame spray pyrolysis (FSP) were loaded with rGO prepared based on Hummer's method with varying concentrations from 0 to 5 wt%. Characterized results by X-Ray diffraction, scanning and transmission electron microscopy, energy dispersive spectroscopy, Raman spectroscopy, X-ray photoemission spectroscopy and nitrogen adsorption confirmed the dispersion of rGO sheets within 5-15 nm FSP-made orthorhombic Bi2WO6 nanoparticles. The gas-sensing data measured in dry air demonstrated that the optimal rGO loading level of 2 wt% provided substantial enhancements of H2S response and selectivity. Specifically, the 2 wt% rGO-loaded Bi2WO6 sensor exhibited the highest response of similar to 29 towards 10 ppm H2S with high selectivity against H-2, CH4, NO, NO2, C7H8, CH2O, C8H10, C6H6, C3H6O, CH3OH, C2H5OH, C3H6O2, C3H6O3, C4H8O2, CH3COOH, C4H9COOH and HCOOH at an optimal working temperature of 350 degrees C. The roles of rGO on gas-sensing behaviors were explained on the basis of p-n heterojunctions between rGO and Bi2WO6. Therefore, the rGO-loaded Bi2WO6 sensor is an attractive candidate for H2S detection.