Effect of bridging hydroxyl on the interfacial charge transfer for photocatalytic degradation of toluene

Abstract

The mechanism of charge transfer to reactants during photocatalytic degradation of volatile organic compounds remains unclear. Herein, TiO2 was heated in a hydrogen atmosphere to increase the content of bridging hydroxyl (OHB), and atmosphere surface photovoltage spectroscopy (ASPV) was used to study the effect of changed surface sites on the transfer of photogenerated charge carriers to reactants (O2, H2O, and toluene). Results showed that the removal rate and mineralization efficiency of toluene were improved after hydrogen treatment. The ASPV tests found that hydrogen treatment created electron transfer channels to O2 and hole transfer channels to toluene/water, and reduced H2O’s interference with electron utilization by O2. Hydrogen in the newly formed OHB changed the electron distribution on the TiO2 surface by injecting electrons. The OHB and surrounding Ti4−x ions altered the adsorption form of H2O, thereby facilitating the transfer of electrons to O2 and holes to toluene.