The W@WO₃ ohmic contact induces a high-efficiency photooxidation performance

The Schottky-type metal-semiconductor (M-S) junction works well in promoting the separation of photogenerated carriers. In this paper, another type of M-S junction, Ohmic contact of W@WO₃, has been developed via an acid partial oxidation strategy. By simply tuning the experimental parameters including the acid concentration and the reaction time, WO₃ nanosheets are epitaxially grown on a W core; moreover, the thickness and density of the WO₃ shell can be finely controlled. The photocatalytic activities of samples are tested via degradation of gaseous acetaldehyde under UV light irradiation. The results show that the W@WO₃ core-shell composite with a thinner and looser WO₃ shell exhibits a higher mineralization ability of acetaldehyde to carbon dioxide. An Ohmic contact between the W core and the WO₃ shell is fairly confirmed by means of photo-electronic measurements. It is believed that the built-in electric field at the interface of the Ohmic contact leads to the migration of photogenerated electrons from WO₃ to W, which is beneficial for separation of the electron-hole pairs and hence an enhanced photooxidation ability.