Room temperature H2S gas sensing performance of VO2(A) nanowires with high aspect ratio

Abstract

Achieving room-temperature detection of H2S gas is crucial for practical applications. In this work, one-dimensional VO2(A) nanowires with high aspect ratio were prepared by a facile one-step hydrothermal method and applied to the detection of H2S at room temperature for the first time. The effects of hydrothermal reaction time on the phase composition, morphology and gas sensing properties of the samples were investigated. It was found that the aspect ratio of VO2(A) nanowires prepared at hydrothermal time of 36 h could reach up to 144.7, thus possessing a higher surface-area-to-volume ratio. The gas sensor based on this structure had an excellent gas-sensing response (up to 2.09) to 10 ppm H2S gas at room temperature, and also showed good selectivity and reproducibility. Density functional theory (DFT) calculations were used to explore the adsorption behavior of H2S molecules on VO2(A) surface. The calculation results revealed that H2S gas could be spontaneously adsorbed on the surface of VO2(A), and during the interaction between VO2(A) and H2S, H2S molecules act as donors and transfer electrons to the surface of VO2(A). Combined with the calculated results, the gas sensing mechanism of VO2(A) nanowires to H2S gas could be attributed to the modulation of the potential barrier height at the intersection of nanowires and the high surface-area-to-volume ratio of the as-prepared nanowires. Our work shows that gas sensors based on VO2(A) nanowires with high aspect ratio have great potential for detecting H2S gas at room temperature.