Surface fluorination of BiVO4 for the photoelectrochemical oxidation of glycerol to formic acid

Abstract

The C–C bond cleavage of biomass-derived glycerol to generate value-added C1 products remains challenging owing to its slow kinetics. We propose a surface fluorination strategy to construct dynamic dual hydrogen bonds on a semiconducting BiVO₄ photoelectrode to overcome the kinetic limit of the oxidation of glycerol to produce formic acid (FA) in acidic media. Intensive spectroscopic characterizations confirm that double hydrogen bonds are formed by the interaction of the F–Bi–F sites of modified BiVO₄ with water molecules, and the unique structure promotes the generation of hydroxyl radicals under light irradiation, which accelerates the kinetics of C–C bond cleavage. Theoretical investigations and infrared adsorption spectroscopy reveal that the double hydrogen bond enhances the C=O adsorption of the key intermediate product 1,3-dihydroxyacetone on the Bi–O sites to initiate the FA pathway. We fabricated a self-powered tandem device with an FA selectivity of 79% at the anode and a solar-to-H₂ conversion efficiency of 5.8% at the cathode, and these results are superior to most reported results in acidic electrolytes.