Electronic state changes of Cu nanoparticles on rutile TiO2(110) by O2 and CO exposure

Abstract

In order to investigate the strong catalytic activities of Cu nanoparticles, we have measured the electronic states of oxygen and carbon monoxide-exposed Cu nanoparticles on the rutile TiO2(110) surfaces by synchrotron radiation photoelectron spectroscopy. After depositing Cu on the oxygen rich TiO2(110) (O-TiO2) surface, the Ti 3d state appeared due to the disappearance of the oxygen adatoms by reaction with Cu. After further oxygen exposure, Cu 3d state drastically changed. This result indicates that Cu2O is formed by oxidation of Cu nanoparticles. We then dosed a CO gas onto the oxidized Cu/O-TiO2(110) surface and found that the work function slightly decreases and elimination of O adatoms is confirmed by medium energy ion scattering. These results obtained clearly shows the reaction of CO with O adatoms adsorbed on Cu/TiO2 probably to form CO2.