Efficient Photoelectrocatalysis of Glycerol to Dihydroxyacetone and Synergistic Hydrogen Generation via Dual Oxidation Pathways Using Co-LDH/Bi<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> Ternary Array
Lu Niu, Rufeng Tian, Wanggang Zhang, Hongxia Wang, Jian Wang, Yiming Liu
Abstract
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/Bi 2 O 3 /TiO 2, by loading particulate Bi 2 O 3 and linear Co-LDH onto a TiO 2 nanorod for glycerol conversion and hydrogen production. The characterization results confirm the formation of coupled interfaces between Co-LDH and Bi 2 O 3 and TiO 2, 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/Bi 2 O 3 /TiO 2 photoanode exhibited stronger adsorption of glycerol intermediate hydroxyl group and more effective desorption of DHA compared to TiO 2 and binary photoanodes (Co-LDH/TiO 2 and Bi 2 O 3 /TiO 2 ), resulting in high-selectivity glycerol conversion to DHA. Mechanistic studies and density function theory calculations have shown that the binary photoanode Co-LDH/TiO 2 oxidizes glycerol mainly through hole oxidation, and the binary photoanode Bi 2 O 3 /TiO 2 oxidizes glycerol mainly through hydroxyl radical ( • OH) oxidation. Therefore, the ternary photoanode constructed (Co-LDH/Bi 2 O 3 /TiO 2 ) 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.