Single ultrathin WO3 nanowire as a superior gas sensor for SO2 and H2S: Selective adsorption and distinct I-V response

Abstract

In order to take insight into the gas sensing performance of single ultrathin WO3 nanowire, we performed first principles calculation to investigate the gas adsorption properties and used non-equilibrium Green function (NEGF) to investigate the electron transport properties of WO3 nanowires with gas adsorption. Our investigation indicated that the WO3 nanowires with/without oxygen vacancies are both sensitive to H2S due to the large adsorption energies and distinct charge transfer. Besides, we found that the WO3 nanowire with Oa type oxygen vacancies is highly selective to SO2. We supposed that the high chemical activity and the small molecular volume of H2S and SO2 are the main reasons of the selectivity. Finally, the negative differential resistance (NDR) effect of single ultrathin WO3 nanowire and the gate voltage were proposed to benefit the application of WO3 nanowires gas sensors. We also supposed two ways to take advantage of the NDR effect of single ultrathin WO3 nanowire in gas sensing applications. It should be noted that this is the first theoretical investigation of WO3 nanowires gas sensors considering the electron transport properties. Our work highlighted the possibility to use the single ultrathin WO3 nanowire as superior gas sensors for SO2 and H2S.