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 ~29 towards 10 ppm H₂S with high selectivity against H₂, CH₄, NO, NO₂, C₇H₈, CH₂O, C₈H₁₀, C₆H_6, 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.