Synthesis of BiVO nanoflakes decorated with AuPd nanoparticles as selective oxidation photocatalysts.

The ultrathin BiVO nanoflakes decorated with Pd and AuPd nanoparticles (NPs) were respectively synthesized and optimized for the enhanced photocatalysis towards selective oxidation of aromatic alcohols. The monometallic Pd(x)-BiVO samples presented hump-like variation in the photocatalytic activity with increasing Pd amount (x) from 0 to 2.0 wt%. Subsequently, coupling Au with Pd on BiVO nanoflakes resulted in a further improvement in the photocatalysis, with retaining the high selectivity (>99%) for aldehyde production. By tuning metal loading, the typical Au(0.5)Pd(0.5)-BiVO photocatalyst exhibited the highest benzaldehyde yield of 887.7 μmol·g·h, which was 6.0 times that of bare BiVO nanoflakes and 1.35 times that of Pd(1.0)-BiVO photocatalyst. A series of characterizations and DFT calculations confirmed the enhanced light harvesting and charge separation of the Au(0.5)Pd(0.5)-BiVO material, owing to the strong electronic couplings in AuPd NPs and its remarkable influence on the band structure of BiVO. The photocatalytic mechanism studies indicated that the selective oxidation of aromatic alcohols was achieved by the cooperation of photogenerated holes and O radical, and this process was promoted by the interfacial synergism between AuPd NPs and BiVO nanoflakes. This work demonstrates a systematic study on optimizing photocatalysts to improve their performance in light-driven organic transformations as well as highlights the synergistic effect of metal-metal coupling and metal-semiconductor interface on photocatalysis.