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

Novel Bi₂W₂O₉ and Bi₂Mo₂O₉ with irregular polyhedron structure were successfully synthesized by a hydrothermal method. Compared to ordinary Bi₂WO₆ and Bi₂MoO₆, the modified structure of Bi₂W₂O₉ and Bi₂Mo₂O₉ 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 Bi₂WO₆, Bi₂MO₆, Bi₂W₂O₉, and Bi₂Mo₂O₉ were examined. UV-Vis diffuse reflectance spectroscopy revealed the visible-light absorption ability of Bi₂WO₆, Bi₂MO₆, Bi₂W₂O₉, and Bi₂Mo₂O₉. Photoluminescence (PL) and photocurrent indicated that Bi₂W₂O₉ and Bi₂Mo₂O₉ 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. [ABSTRACT FROM AUTHOR]