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.