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

Abstract

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.