Activation of Photocatalytic Water Oxidation on N-Doped ZnO Bundle-like Nanoparticles under Visible Light

Nitrogen-doped ZnO bundle-like nanoparticles were prepared by heating ZnOHF precursor at different temperatures under an ammonia atmosphere. ZnOHF gradually transformed to N-ZnO with the increase of the heating temperature, and the as-prepared N-ZnO nanoparticles preserved the original morphologies of ZnOHF at moderate heating temperature. The N-ZnO nanoparticles demonstrated drastically enhanced absorption in the visible region compared with the commercial ZnO and N-ZnO derived from commercial ZnO. Theoretical calculations indicated that the contribution of nitrogen to the top of the valence band (VB) of ZnO plays the major role of extending the absorption of ZnO to the visible region. The as-prepared N-ZnO showed high photocatalytic activity for the visible-light-induced water oxidation, and the activity can be further greatly enhanced by loading IrO2 cocatalyst. To our knowledge, this is the first report of realizing photocatalytic water oxidation on non-metal-doped ZnO under visible light without applied bias, thus adding new value to the band gap engineering of benchmark ZnO for efficient solar energy utilization.