Atomic Cu adsorption on SrTiO3(0 0 1) surface was studied via the first-principles calculations. On TiO2-terminated(0 0 1) surface, Cu prefers to be adsorbed at a 4-hold hollow site and covalently bonds four oxygen atoms. Work function is lowered due to the charge transfer from Cu to SrTiO3. On SrO-termination, Cu is adsorbed over an oxygen atom and intra-unit charge polarization mainly contributes to the bonding. It has been identified that Cu plays as an electron trapping center and a mediating role in charge transfer from photon excited SrTiO3 to target compounds. The photogenerated electron-hole pairs can be separated effectively. (C) 2011 Elsevier B.V. All rights reserved.