Theoretical insights into the adsorption of monatomic Ag on the (2 x 2) BiOCl (001) surfaces

The adsorption energies, geometric structures, electronic properties, work functions and surface dipole moments of monatomic Ag adsorption on the (2 x 2) BiOCl (001) surfaces, including the 1Cl-, BiO- and 2Cl-terminated BiOCl (0 0 1) surfaces, have been investigated using first-principles calculations based on density functional theory. The most energetically favorable adsorption configuration of single Ag atom is at the fourfold hollow site, with the minimum adsorption energies of -0.465, -2.954 and -8.080 eV for the 1Cl-, BiO- and 2Cl-terminated BiOCl (0 0 1) surfaces, respectively. The analysis results of electronic properties indicate that there are new intermediate energy states mainly contributed to Ag 4d and Cl 3p states for 2Cl-terminated (0 0 1) surface, and Ag 5s states for 1Cl- and BiO-terminations. In addition, Ag adsorption can induce the formation of surface dipole moment and change in work function by the interfacial charge transfer. Combined with the previously reported experiments, the charge transport mechanism and effective separation processes of photo-induced electron-hole pairs of Ag/BiOCl photocatalytic system are built up and discussed. More importantly, our calculated findings could afford the theoretical basic knowledge for further understanding the microscopic structures, electronic properties, and photocatalytic reaction mechanism of Ag/BiOCl photocatalyst, providing a new analysis calculation for potential application in the investigation on the Ag/BiOBr and Ag/BiOI as well as other noble metals/BiOCl catalytic systems. (C) 2014 Elsevier B.V. All rights reserved.