Selective Oxidation of Benzyl Alcohol by Ag/Pd/m-BiVO4 Microspheres under Visible Light Irradiation

A series of Ag/Pd/m-BiVO4 (monoclinic) bimetallic photocatalytic materials with different loading amounts and different mass ratios of Ag and Pd were synthesized by a hydrothermal method and an NaBH4 reduction method. The Ag/Pd/m-BiVO4 photocatalyst with a total Ag and Pd loading of 2 wt% and an Ag-to-Pd mass ratio of 2:1 can selectively oxidize benzyl alcohol to benzaldehyde under visible light irradiation, the conversion rate was up to 89.9%, and the selectivity was greater than 99%. The conversion rate on Ag/Pd/m-BiVO4 was higher than those on Ag/m-BiVO4 and Pd/m-BiVO4. The photocatalysts were characterized by X-ray powder diffraction (XRD), ultraviolet-visible diffuse reflection spectroscopy (UV-vis DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, N-2 adsorption-desorption isothermal curves (BET) and other means. The effects of different light wavelengths and light intensities were compared. Then, the effects of different alcohol derivatives on the reactions were explored. The cycle experiments proved that the Ag/Pd/m-BiVO4 photocatalyst had good light stability and thermal stability. In addition, the capturing experiment of active species shows that the selective oxidation of benzyl alcohol is mainly accomplished through the synergistic action of h(+), e(-), center dot OH and center dot O-2(-).