Heteroatomic Ni, Sn Clusters-Grafted Anatase TiO2 Photocatalysts: Structure, Electron Delocalization, and Synergy for Solar Hydrogen Production

This work shows the molecular engineering of metal active sites on the surface of anatase nanoparticles, based on the fundamental of metal-to-metal charge transfer (MMCT). A series of Sn, Ni-co-modified TiO2 photocatalysts were prepared by use of surface organometallic chemistry. Photocatalytic hydrogen production from ethylenediaminetetraacetic acid disodium salt solution as a model reaction was used to evaluate the photocatalytic properties of the materials. The chemical states of the modifiers were characterized by a combination of various spectroscopic techniques. These results clearly reveal the synergy of atomically isolated Ni and Sn centers for solar-to-hydrogen conversion. A near 10-fold enhancement of hydrogen production is achieved on Sn, Ni-co-grafted TiO2 photocatalysts under solar light irradiation. Detailed characterization suggests that the synergy is closely related to the [-O-Ti-O-Sn-O-Ni-O-Ti-] heteroatomic clusters with the eight-member cyclic structure. An electron-delocalization loop is proposed for efficient separation of charges photogenerated in bulk TiO2 and excitons generated in Ni-O-Ti molecular linkages.