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

Abstract

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 ~29 towards 10 ppm H2S with high selectivity against H2, CH4, NO, NO2, C7H8, CH2O, C8H10, C6H6, C3H6O, CH3OH, C2H5OH, C3H6O2, C3H6O3, C4H8O2, CH3COOH, C4H9COOH and HCOOH at an optimal working temperature of 350 °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.