Effects of single metal atom (Pt, Pd, Rh and Ru) adsorption on the photocatalytic properties of anatase TiO2

Abstract

The effects of single metal atom (Pt, Pd, Rh and Ru) adsorption on the photocatalytic properties of anatase TiO2 are investigated by means of the first-principles calculations based on density functional theory (DFT). Our results show that the most stable adsorption site for single metal atom on anatase TiO2 (101) surface is the bridge site formed by two twofold coordinated oxygen (O2c) atoms at the step edge. Due to the charge transfer from metal atoms to anatase TiO2 (101) surface, the work function of adsorbed surface is significantly smaller than the clean one, indicating enhanced surface activity. Fukui functions are highly localized around the isolated metal atoms, indicating that single metal atoms on anatase TiO2 (101) surface serve as the active reduction and oxidation sites in the photocatalytic process. Photo-induced electrons in the electronically excited TiO2 photocatalyst can be transferred to target species through the deposited single atoms. The band structures of host TiO2 are almost unchanged upon the adsorption, and the metal induced states are located in the band gap of the host. Remarkably, due to the metal atoms adsorption, the upward shift of conduction band edge will improve the reducing capacity of anatase TiO2. Moreover, when single metal atoms are adsorbed, potential energy of topmost surface Ti atoms turns to get close to the vacuum level, which significantly facilitates the electron transfer for hydrogen evolution. Results in this work provide new insights into improving the photocatalytic performance by single metal atoms adsorption.