Surface electron structures and mechanism of nonradiative transitions on crystalline TiO2 nanoparticles

Surface photovoltage spectroscopy and photoacoustic spectroscopy were combined to explore the surface electron structures of anatase TiO2 nanoparticles and their reorganization induced by the presence of the rutile phase. The presence of the rutile phase on the nanoparticles created a new surface state Ti3d(s2)3+, at the same time decreased the state density of Ti3d(s1)3+. The critical weight fraction of the rutile phase was demonstrated 8 wt%, above which the surface electron structure of anatase TiO2 nanoparticles was turned from anatase to rutile-like. It was found after the relationship of the photogenic free charge carriers and the nonradiative transitions was confirmed that the surface electron reorganization greatly suppressed the nonradiative transitions.