Localization and Stabilization of Photogenerated Electrons at TiO₂ Nanoparticle Surface by Oxygen at Ambient Temperature

Abstract

Understanding the mechanism by which oxygen adsorption influences the separation behavior of charge carriers is important in photocatalytic removal of air pollutants. In this study, we performed steady-state surface photovoltage and surface photocurrent spectroscopy combined with an atmosphere control system to determine the effect of oxygen on the charge separation behavior at the surface of anatase TiO nanoparticles at ambient temperature. Results showed that photogenerated electrons were movable in N atmosphere but were localized in O atmosphere. O obviously enhanced the stabilization of the localized photogenerated electrons when the surface defects of TiO were fully occupied by adsorbed O. Moreover, O adsorption increased the energy demand for exciting electrons from the valence band to localized surface defect states and reduced the density of band tail states. These findings suggest us that the effect of gaseous species on the mobility and stability of charge carriers should be considered to understand the photocatalytic degradation of air pollutants.

Conversion of methanol on rutile TiO2(110) and tungsten oxide clusters: 2. The role of defects and electron transfer in bifunctional oxidic photocatalysts

“…1,21 Indeed, photogenerated holes exhibited longer lifetimes on anatase TiO 2 nanoparticles due to interaction with adsorbed oxygen in combination with Ti 3+ defect sites. 69 This matches our finding that the presence of oxygen appears crucial for the photo-oxidation. Also defect induced localized surface states may contribute to this effect.…”

Synergistic effects of Au and PdOx on the solar-assisted catalytic ozonation of VOCs

“…The SPV signal in an Ar atmosphere represents the intrinsic carrier separation behavior. 37 The prepared samples had no SPV signal in Ar atmosphere, indicating that photogenerated carriers were not effectively separated. O 3 is a typical electron acceptor.…”

Photocatalytic Activity Enhancement of Anatase/Rutile‐Mixed Phase TiO2 Nanoparticles Annealed with Low‐Temperature O2 Plasma

“…More oxygen molecules and radicals are preferentially adsorbed on more subsurface oxygen vacancies introduced, capturing or sharing excess electrons located on the oxygen vacancy sites. [55][56][57][58] As a result, this oxygen adsorption contributes to increasing the upward band-bending at the surface. [59] The oxygen adsorption also depresses the residual charged carrier concentration, reducing the electrical conductivity of the plasma-assisted-annealed sample (Figure 14 and 15).…”