Pivot roles of noble metal in single-phase TaXzON (0 < Z ≤ 0.001) and heterostructured Xδ/TaXz-δON (X = Pt, Ru, 0.001 < Z ≤ 0.016) visible light photocatalysts based on photoinduced interfacial charge transfer for hydrogen production

Noble metal modification has been demonstrated to be an efficient strategy to improve the photocatalytic performance of TaON photocatalysts. However, the previous studies about the noble metal modification are only restricted to the surface loading of metallic noble metal, investigations have seldom been focused on the simultaneously deposited and doped X/TaXzON (X = Pt, Ru) photocatalyst. In this work, single-phase Ta1-zXzO1+zN1-z (X = Pt, Ru, 0 < Z <= 0.001) (as TaXzON) and heterostructured X-delta/Ta1-z+delta Xz-delta O1+z-dN1-z+delta (X = Pt, Ru, 0.001 < Z <= 0.016) (as X-delta/TaXz-delta ON) photocatalysts were synthesized by a sol-gel method in combination with a post-treatment nitridation process. The chemical states and form of noble metals in the as-prepared TaXzON and X-delta/TaXz-delta ON samples were characterized by XPS and HRTEM. In a few noble metal doping sol-gel processes, the visible-light photocatalytic activity of single-phase TaPtzON (Z = 0.0005) and TaRuzON (Z = 0.0005) showed a rate of H-2 production at 51 and 90 mu mol h(-1) higher than that of the pristine TaON. With the increase of noble metal content, the photocatalytic activity of heterostructured Pt-delta/TaPtz-delta ON (Z = 0.004) and Ru-delta/TaRuz-delta ON (Z = 0.004) exhibited a rate of H-2 evolution at 198 and 258 mu mol h(-1) which was about 28 and 6 times than the TaON loaded noble metal by photodeposition, respectively. Moreover, further photodeposition of noble metal was performed at the heterostructured materials. It was found that the highest photocatalytic activity of the catalyst was achieved based on X-delta/TaXz-delta ON (X = Pt, Ru, Z = 0.002). This enhanced photocatalytic activity is mainly ascribed not only to the doping effect leading to formation of an isolated energy level contributing to more visible-light absorption but also to the well-distributed noble metal on the surface of the photocatalysts with strong interaction with TaON resulting in photoinduced interfacial charge transfer. This work may provide some insight into the smart design of novel and high-efficiency photocatalytic materials.