Nano-scaled silver vanadates loaded on mesoporous silica: Characterization and photocatalytic activity

Visible-light active silver vanadates (SVOs) loaded on mesoporous silica (SBA-15) were synthesized using a wetness impregnation procedure. All the SVO/SBA-15 composites inherit the higher photocatalytic activities and larger mineralization yields than those of P-25 (commercial TiO2) and plain SVO. Moreover, the sample loaded with 51% of SVO (51SVO/SBA-15) exhibits the best photocatalytic activity. Morphology results show that the addition of mesoporous SBA-15 favors the formation of nano-scaled silver vanadates. Surface characterization by the diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) confirms that the presence of surface hydroxyl groups on SVO/SBA-15 composites is beneficial to the adsorption kinetics. Accompanied with the results of photoluminescence spectra, the hydroxyl groups also serve as the hole-trapping centers that effectively inhibit the electron–hole recombination rate on the SVO/SBA-15 composites. Both high density of surface hydroxyl groups and low recombination rate of photogenerated charges are considered as the main factors that causes the outstanding photocatalytic activity of SVO/SBA-15 composites.