Synthesis of BiVO4 nanoflakes decorated with AuPd nanoparticles as selective oxidation photocatalysts.

The ultrathin BiVO4 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)-BiVO4 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 BiVO4 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)-BiVO4 photocatalyst exhibited the highest benzaldehyde yield of 887.7 µmol·g-1·h-1, which was 6.0 times that of bare BiVO4 nanoflakes and 1.35 times that of Pd(1.0)-BiVO4 photocatalyst. A series of characterizations and DFT calculations confirmed the enhanced light harvesting and charge separation of the Au(0.5)Pd(0.5)-BiVO4 material, owing to the strong electronic couplings in AuPd NPs and its remarkable influence on the band structure of BiVO4. The photocatalytic mechanism studies indicated that the selective oxidation of aromatic alcohols was achieved by the cooperation of photogenerated holes and O2- radical, and this process was promoted by the interfacial synergism between AuPd NPs and BiVO4 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.

Understanding size-dependent properties of BiOCl nanosheets and exploring more catalysis.

Investigating the dependence of the catalysis on the size and structure of materials is of great significance for exploiting catalysts with characteristics of high activity, low cost, and new property. Non-precious metal catalysts bear high hope to meet the increasing demands of industrial applications in a cost-effective and environmentally friendly way. In this work, we take size-controlled BiOCl nanosheets as examples, which are synthesized via a hydrothermal method by changing the reaction conditions. The BiOCl nanosheets were characterized in details to understand their size-property relationships, and were found to exhibit a series of thickness-dependent physicochemical properties, including specific surface area, light absorption, and the separation efficiency of photo-generated charge carriers. Moreover, this work demonstrates the first example that BiOCl nanostructures have very high catalytic activity for the reduction of nitrophenols by sodium borohydride, without any light irradiation. The high catalytic activity of BiOCl nanosheets was proved to be due to the metallic Bi0 clusters that were produced by surface Bi (III) reduction. The catalytic activity increased greatly with a decrease in the average thickness from 106.42nm of BiOCl(H2O) to 3.47nm of ultrathin BiOCl, because the increased specific surface area provided more active sites for catalytic reactions. As a result, this work provides evidences for the size-property relationships of nanostructured catalysts as well as some inspirations for exploiting novel heterogeneous catalysis of BiOCl nanomaterials.