Metallic Bi Nanocrystal-Modified Defective BiVO4 Photoanodes with Exposed (040) Facets for Photoelectrochemical Water Splitting

Metallic Bi nanocrystal-modified defective BiVO4 photoanodes with exposed (040) facets were synthesized though the NaBH4 solution reduction method. B-O bonding at the surface of BiVO4 photoanodes is destroyed, which results in the removal of O atoms and forms oxygen vacancies at the beginning stage of the reduction process, and then Bi3+ ions are reduced to nanometer-scale metallic Bi that is dispersed uniformly over the surface. BiVO4 photoanodes with this special structure exhibits a high performance for photoelectrochemical water splitting, owing to the synergistic effect of oxygen vacancies and metallic Bi. The presence of oxygen vacancies could significantly increase the capture ability of photogenerated electrons and improve the adsorption properties of H2O molecules in the process of photoelectrochemistry. Metallic Bi nanocrystals on the surface of BiVO4 photoanodes are beneficial for the photo-response range as well as the separation and consumption of photogenerated carriers, owing to the surface plasmon resonance effect of Bi. In addition, the formation and function mechanism of metallic Bi and oxygen vacancies is discussed in detail.