Highly efficient BiVO4 single-crystal photocatalyst with selective Ag2O-Ag modification: orientation transport, rapid interfacial transfer and catalytic reaction

Abstract

Coupling crystal-facet engineering with selective interfacial modification has been demonstrated to be an effective strategy to enhance the photocatalytic performance of semiconductor photocatalysts. For instance, BiVO₄ exhibited excellent photocatalytic activity when Pt cocatalyst was selectively modified on the (010) facet of BiVO₄ single-crystal photocatalyst with exposed (010) and (110) facets. In view of the high cost and rarity of metallic Pt, it was desirable to discover low-cost electron cocatalysts that show comparable activity with Pt. In the study, Ag₂O-Ag as a novel and highly efficient electron cocatalyst was selectively modified on the (010) facet of single-crystal BiVO₄ photocatalyst via facile photodeposition of metallic Ag and its subsequent partial oxidation to Ag₂O via low-temperature calcination (100–400 °C). In detail, Ag was selectively modified on the electron-rich (010) facet of BiVO₄ single crystal, while Ag₂O was selectively formed on the Ag surface, resulting in the formation of Ag₂O-Ag/BiVO₄ photocatalyst. As a result, Ag₂O-Ag/BiVO₄ exhibited nearly comparable activity with Pt/BiVO₄, but clearly higher activity than Ag/BiVO₄ or BiVO₄ alone. The enhanced performance was ascribed to the synergistic effect of crystal-facet engineering of BiVO₄ and selective modification of Ag₂O-Ag electron cocatalyst. In detail, the single crystal structure of BiVO₄ results in the orientation transport of photogenerated carriers, while metallic Ag effectively transfers photogenerated electrons of BiVO₄ and then, Ag₂O as the active site accelerates the reduction of dissolved oxygen. Considering that our present synthetic strategy is facile, controllable and economical, this study provides insight into the design and synthesis of highly efficient semiconductor photocatalysts.