Study on adsorption and gas sensitive behavior of WO3 (002) and (200) crystal planes

When organic molecules are detected by gas-sensitive test, an oxidation-reduction reaction is triggered to consume adsorbed oxygen, and the change of material conductance resulting from the consumption of adsorbed oxygen is detected. In this paper, the molecular adsorption and gas-sensitive behavior of WO3 (200) and (002) crystal planes are investigated. Density functional theory (DFT) simulations reveals that ethanol (C2H5OH) and oxygen molecules (O2) have different adsorption active sites on the (200) and (002) crystal planes, there is no adsorption competition between C2H5OH molecules and O2 molecules on the crystal plane, resulting the two crystal planes exhibit excellent selectivity for ethanol gas. Compared with other molecules, acetone (C2H6CO) and O2 occupy the closest adsorption active sites on the (200) crystal plane, resulting in increased adsorption competition, which prolongs the response time and reduces the gas-sensitive selectivity. The molecular adsorption behavior holds important theoretical significance for studying the gas-sensitivity properties of materials.