Electrical characterization of H2S adsorption on hexagonal WO3 nanowire at room temperature

We have characterized the electrical transport properties of Au/WO3 nanowire/Au devices in ambient air and gaseous H2S to investigate the adsorption kinetics of H2S molecules on the surface of WO3 nanowire at room temperature. The WO3 nanowire devices exhibit increasing linear conductance and electrical hysteresis in H2S. Furthermore, the contact type between Au electrode and WO3 nanowire can be converted from original ohmic/Schottky to Schottky/ohmic after being exposed to H2S. These results suggest that adsorbed H2S molecules are oxidized by holes to form hydrogen ions and S atoms, which will result in formation of hydrogen tungsten bronze and desorption of previously chemically adsorbed H2O molecules. Adsorbed H2S molecules can also oxidize previously adsorbed and ionized oxygen, which will release the electrons from the ionized oxygen and then weaken upward band bending at the surface of WO3 nanowire. (C) 2014 AIP Publishing LLC.