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

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 O_a 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.