Theoretical and experimental study on competitive adsorption of SF6 decomposed components on Au-modified anatase (101) surface

Partial discharge inside gas insulated switchgear in electric systems will lead to the decomposition of SF6 gas, the insulating medium, producing several kinds of characteristic components. Detecting the species and concentrations of decomposed components of SF6 is considered a feasible way of early-warning to avoid occurrence of sudden fault. As a research hotspot in gas-sensing field, TiO2 nanotubes possess wide application prospect in online monitoring of fault gases in gas insulated switchgear. In this paper, adsorption parameters of SO2, SOF2, and SO2F2, characteristic products of SF6 decomposition, on Au-doped anatase TiO2 (101) surface were calculated using software Materials Studio. The adsorption processes of gas molecules on Au-doped anatase TiO2 (101) surface were theoretically analyzed, which can be used to explain the gas-sensing mechanism of TiO2 nanotubes sensor. Besides, adsorption parameters of Au-doped anatase TiO2 (101) surface were compared with those of intrinsic anatase TiO2 (101) surface. As can be concluded, Au doping changes the sensitivity and selectivity of TiO2 nanotubes to the above three kinds of gases. Furthermore, gas-sensing experiment of intrinsic and Au-doped TiO2 nanotubes to SO2, SOF2, and SO2F2 was carried out, of which the results were consistent with simulation analysis. Research of this paper illustrates sensitive and selective changes of TiO2 nanotubes gas sensor after Au doping, which lays foundation for preparation of gas sensors applied for detection of partial discharge inside gas insulated switchgear.