One-Step Decoration of Subnanometer MoO_x Clusters on Bi₁₁VO₁₉ Nanotubes for Visible-Light-Driven Water Oxidation

For the sluggish reaction kinetics due to a four-electron transfer process, water oxidation is always a major obstacle to solar splitting of water to hydrogen. It remains a tough challenge to develop efficient nonnoble-metal photocatalysts for water oxidation. Herein, we decorate the host photocatalyst of Bi₁₁VO₁₉ nanotubes with the coatalyst of subnanometer MoO_x clusters (denoted as Bi₁₁VO₁₉/MoO_x hetero-nanotubes) via a one-step cation-exchange solvothermal reaction using Na₂V₆O₁₆ nanowires as the hard template. It is observed that the morphology and microstructure of Bi₁₁VO₁₉/MoO_x hetero-nanotubes vary with the dosage of Mo source and polyvinylpyrrolidone, as well as with the solvent composition. The optimized Bi₁₁VO₁₉/MoO_x hetero-nanotubes significantly enhance the photooxidation of water to oxygen with visible light, delivering an oxygen production rate of 790 μmol g^-1 h^-1, which is 12 times that of bare Bi₁₁VO₁₉ nanotubes. In situ X-ray photoelectron spectroscopy and (photo)electrochemical characterization suggest that the enhanced photoactivity may be caused by the decorated cocatalyst of MoO_x clusters, which extracts electrons from Bi₁₁VO₁₉ nanotubes, leaving an abundance of holes for water photooxidation. This work demonstrates a potential strategy to develop photocatalysts for energy conversion by constructing Bi₁₁VO₁₉-based nanostructures.