CuO[sbnd]Co3O4 nanoparticle catalysts rich in oxygen vacancies toward upgrading anodic electro-oxidation of glycerol

Abstract

The replacement of the anodic oxygen evolution reaction in water electrolysis with the glycerol electro-oxidation reaction not only lowers the anodic potential and enhances hydrogen production efficiency at the cathode, but also yields valuable chemicals at the anode, thereby improving overall economic viability. The development of efficient and cost-effective catalysts for the electro-oxidation reaction of glycerol remains a significant challenge. Here, CuOCo3O4 loaded on nickel foam (CuOCo3O4/NF) is in situ prepared by solvothermal methods. The analysis of scanning electron microscopy reveals that CuOCo3O4 consists of micrometer-scale spherical particles, which are further assembled by even smaller nano-scale particles. The combination of Cu and Co in the catalyst induces lattice strain, as characterized by Raman and X-ray photoelectron spectroscopy, leading to an increased generation of oxygen vacancies. The electrochemical tests demonstrate that CuOCo3O4/NF exhibits superior electrocatalytic activity at a Cu:Co molar ratio of 1:1, requiring only 1.13 V vs RHE to achieve a current density of 10 mA cm−2. This performance surpasses other ratios as well as monometallic CuO and Co3O4. The CuOCo3O4/NF║CuOCo3O4/NF two-electrode system requires 1.46 V to achieve a current density of 50 mA cm −2 and exhibits excellent stability during a 12 h testing period. The electrolysis products consist of formic acid, glycolic acid, and glyceric acid, with the highest selectivity recorded at 90.3 % for formic acid. The high electrocatalytic performance of the CuOCo3O4/NF catalyst can be attributed to its spherical structure and the presence of oxygen vacancies.