Effect of ZnO Nanostructure Morphology on the Sensing of H2S Gas

Detection of pollutant gases, such as H 2 S, is of high importance for health reasons. We examine the effect of ZnO nanostructure morphology on the sensing mechanism of H 2 S, using density functional theory calculations. The effect of nanostructure size and shape, gas coverage, and reaction temperature are analyzed in order to determine the effect that each has on the gas–surface reaction. We show that H 2 S dissociatively chemisorbs on the nanowire and faceted-nanotube as H and SH, while H 2 S molecularly physisorbs on the nanotube. H 2 S can adsorb in multiple locations and orientations on the nanowire and faceted-nanotube with the faceted-nanotube providing a greater number of surface sites due to its larger outer surface area and the fact that H 2 S can also adsorb on the inside of the structure. H 2 S acts as a charge donor, causing a decrease in the band gap after adsorption on the nanowire and faceted-nanotube, while the band gap for the nanotube remained almost unchanged after H 2 S adsorption. Using ab initio molecular dynamics simulations, we show that H 2 S may poison the nanowire and faceted-nanotube surface, while H 2 S causes the nanotube structure to distort significantly.