Rationally Designed Bi(2)M(2)O(9) (M = Mo/W) Photocatalysts with Significantly Enhanced Photocatalytic Activity

Novel Bi(2)W(2)O(9) and Bi(2)Mo(2)O(9) with irregular polyhedron structure were successfully synthesized by a hydrothermal method. Compared to ordinary Bi(2)WO(6) and Bi(2)MoO(6), the modified structure of Bi(2)W(2)O(9) and Bi(2)Mo(2)O(9) were observed, which led to an enhancement of photocatalytic performance. To investigate the possible mechanism of enhancing photocatalytic efficiency, the crystal structure, morphology, elemental composition, and optical properties of Bi(2)WO(6), Bi(2)MO(6), Bi(2)W(2)O(9), and Bi(2)Mo(2)O(9) were examined. UV-Vis diffuse reflectance spectroscopy revealed the visible-light absorption ability of Bi(2)WO(6), Bi(2)MO(6), Bi(2)W(2)O(9), and Bi(2)Mo(2)O(9). Photoluminescence (PL) and photocurrent indicated that Bi(2)W(2)O(9) and Bi(2)Mo(2)O(9) pose an enhanced ability of photogenerated electron–hole pairs separation. Radical trapping experiments revealed that photogenerated holes and superoxide radicals were the main active species. It can be conjectured that the promoted photocatalytic performance related to the modified structure, and a possible mechanism was discussed in detail.