Facile construction of a BiVO4/CoV-LDHs/Ag photoanode for enhanced photo-electrocatalytic glycerol oxidation and hydrogen evolution

Abstract

Replacing water oxidation by the thermodynamically more favorable glycerol oxidation reaction in a photoelectrochemical (PEC) cell is highly desirable, which can not only improve the energy efficiency of hydrogen evolution, but also produce value-added chemicals, given that glycerol is easily accessible as a major byproduct from the biodiesel industry. Herein, a BiVO₄/CoV-LDHs/Ag photoanode has been fabricated via a simple electrodeposition and redox strategy, which exhibits excellent PEC activity toward glycerol oxidation. A high photocurrent density of 7.15 mA cm⁻² can be achieved at 1.23 V vs. reversible hydrogen electrode, in 0.5 M Na₂SO₄ solution with 0.1 M glycerol under AM 1.5G illumination, which is 2.7 times that of the pristine BiVO₄ photoanode. The significantly enhanced PEC performance can be attributed to the narrowed optical band gap, and improved charge separation and injection efficiencies after surface deposition of CoV-LDHs/Ag on the BiVO₄ photoanode. As a result, greatly improved hydrogen production efficiency has been achieved by coupling the photo-electrochemical glycerol oxidation on the BiVO₄/CoV-LDHs/Ag photoanode, with the evolved hydrogen gas (123.5 mmol m⁻² h⁻¹) nearly double that when using the pristine BiVO₄ photoanode.