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Replacing the oxygen evolution reaction (OER) in photoelectrocatalytic (PEC) water splitting with glycerol oxidation reaction (GOR) not only enhances hydrogen production but also generates high-value glycerol byproducts. In this study, we developed a ternary photoanode, Co-LDH/Bi2O3/TiO2, by loading particulate Bi2O3 and linear Co-LDH onto a TiO2 nanorod for glycerol conversion and hydrogen production. The characterization results confirm the formation of coupled interfaces between Co-LDH and Bi2O3 and TiO2, which improves the visible light utilization and promotes the formation of type II heterojunctions, resulting in a significant suppression of electron–hole recombination and an improvement in the PEC performance. Fourier transform infrared (FT-IR) spectroscopy revealed that the Co-LDH/Bi2O3/TiO2 photoanode exhibited stronger adsorption of glycerol intermediate hydroxyl group and more effective desorption of DHA compared to TiO2 and binary photoanodes (Co-LDH/TiO2 and Bi2O3/TiO2), resulting in high-selectivity glycerol conversion to DHA. Mechanistic studies and density function theory calculations have shown that the binary photoanode Co-LDH/TiO2 oxidizes glycerol mainly through hole oxidation, and the binary photoanode Bi2O3/TiO2 oxidizes glycerol mainly through hydroxyl radical (•OH) oxidation. Therefore, the ternary photoanode constructed (Co-LDH/Bi2O3/TiO2) with a dual heterojunction converts glycerol through the dual pathways of hole oxidation and •OH oxidation. This work demonstrates a promising strategy for developing high-performance photoanodes in PEC systems for glycerol oxidation and hydrogen production, leveraging the synergistic effects of multisemiconductor heterojunctions and multiple oxidation pathways, offering significant potential for practical applications.
Niu et al. (Wed,) studied this question.