Electronic charge transfer between Au nano-particles and TiO2-terminated SrTiO3(0Â 0Â 1) substrate

The interaction between Au nano-particles and oxide supports is recently discussed in terms of the catalytic activities. This paper reports the electronic charge transfer between Au nano-particles and TiO2-terminated SrTiO3(0 0 1) substrate, which is compared with that for stoichiometric(S)-, pseudo-stoichiometric(S∗)- and reduced(R)-TiO2(1 1 0) supports. We observed the photoelectron spectra of Au 4f, O 2s, Ti 3p, and Sr 4p lines and also measured the work functions for Au/oxides supports using synchrotron-radiation light. As the results, all the O 2s, Ti 3p, and Sr 4p lines for Au/SrTiO3(0 0 1) show lower binding energy shifts in a quite same manner and abrupt increase in the work function is seen in an initial stage. This clearly evidences an electronic charge transfer from the substrate to Au probably due to a much larger work function of Au than SrTiO3(0 0 1), which leads to an upward band bending (0.3 eV) just like a Schottky contact. Electronic charge transfers also take place at Au/S- and Au/S∗-TiO2(1 1 0) and Au/R-TiO2(1 1 0) interfaces, where electrons are transferred from Au to S- and S∗-TiO2 and from R-TiO2 to Au, as predicted by ab initio calculations.