Atomic Pt and molecular H2O adsorptions on SrTiO3 with and without Nb-doping: Electron trapping center and mediating roles of Pt in charge transfer from semiconductor to water

H2O adsorption on SrO-terminated SrTiO3 (0 0 1) surface has been investigated with the first-principles calculation based on DFT. An energy barrier of 0.221 eV for H2O dissociation is obtained, which illustrates a spontaneous dissociation. H and O atoms on the SrO-termination of (0 0 1) surface recombine readily. It demonstrates that Pt induces surface dipole moment and changes the surface work function. Adsorption of atomic Pt on SrO-termination of Nb-doped SrTiO3 (0 0 1) surface indicates charge transfer from the surface to Pt, i.e., Pt is negatively charged. Fukui functions illustrate the role Pt played in mediating charge transfer from (0 0 1) surface to targets adsorbed on Pt. H2O adsorption on the Pt atom supported on Nb-doped SrTiO3 confirms the charge transfer from semiconductor containing electrons to target species, which is mediated by metal. Charge transfer from negatively charged Pt to H2O weakens (activates) the H–O bonds in molecule H2O.