Effects of Surface Terminations of 2D Bi₂WO₆ on Photocatalytic Hydrogen Evolution from Water Splitting

Two-dimensional (2D)-structured photocatalysts with atomically thin layers not only have the potential to enhance hydrogen generation efficiency but also allow more direct investigations of the effects of surface terminations on photocatalytic activity. Taking 2D Bi₂WO₆ as a model, we found that the configuration of bilayer Bi₂O₂ sandwiched by alternating WO₄ layers enabled the thermodynamic driving potential for photocatalytic hydrogen evolution. Without Pt deposition, the H₂ generation efficiency can reach to 56.9 μmol/g/h by 2D Bi₂WO₆ as compared with no activity of Bi₂WO₆ nanocrystals under simulated solar light. This configuration is easily functionalized by adsorption of Cl^-/Br^- to form Bi-Cl/Bi-Br bonds, which leads to the decrease of recombination in photogenerated charge carriers and narrower band gaps. This work highlights an effective way to design photocatalysts with efficient hydrogen evolution by tuning the surface terminations.