Towards understanding the photocatalytic activity enhancement of ordered mesoporous Bi2MoO6 crystals prepared via a novel vacuum-assisted nanocasting method

Abstract

Bi₂MoO₆ is an outstanding semiconductor photocatalyst and has been extensively studied; the construction of ordered mesoporous Bi₂MoO₆, however, remains a great challenge. Herein, for the first time, ordered mesoporous Bi₂MoO₆ crystals were synthesized employing a novel vacuum-assisted nanocasting method. More interestingly, this nanocasting method creatively utilized the amorphous complex as a precursor instead of metal salt ions, by which a new kind of single phase Bi₂MoO₆ (M-Bi₂MoO₆) could be successfully prepared. The as-prepared M-Bi₂MoO₆ exhibited much enhanced photocatalytic activity, which is about 5 times higher than that of conventional Bi₂MoO₆ for the photodegradation of RhB, BPA, CBZ or the photocatalytic reduction of Cr(VI). More importantly, in this paper, through some quantitative results, the mechanism of the photocatalytic activity enhancement of ordered mesoporous Bi₂MoO₆ was thoroughly investigated. Compared to conventional Bi₂MoO₆, the nanometer-sized, ordered mesoporous structure can make the as-prepared M-Bi₂MoO₆ possess excellent light harvesting ability, higher charge separation efficiency and larger catalysis activity areas, which are beneficial for photocatalytic oxidation and reduction. In summary, this work not only constructed a new kind of ordered mesoporous nanomaterial and provided a new vacuum-assisted nanocasting method, but also offered scientific insights into the photo-electron conversion property and carrier transport mechanism.