Atomic Au adsorption on the SrO-termination of SrTiO3 (0 0 1) surface has been studied by means of the first-principles calculations based on the density functional theory (DFT). It indicates that charge polarization dominantly contributes to the bonding between Au and SrO-termination. Interfacial charge transfer induces dipole moment and changes work function. The mediating role Au played in charge transfer from electron-doped SrTiO3:Nb to NO has been simulated. Charge transfer from SrTiO3:Nb to Au is ascertained indicating that Au plays as an electron trapping center. SrO-termination has weak activity to NO while the molecule can be strongly adsorbed on negatively charged Au atom. It has been represented that Au mediates the charge transfer from SrTiO3:Nb to NO. Antibonding orbital (pi(2p)*) of NO accommodates the charge and thus molecular bond is weakened (activated). Fukui functions demonstrate the role Au played in transiting the charge transfer from electronically excited SrTiO3 to target species. Evidence that metal deposited on photocatalyst surface effectively separates the electron-hole pairs and improves the photocatalytic activity is presented in the current work. (C) 2011 Elsevier B. V. All rights reserved.