Dual-vacancy engineering of CuCoOOH synergistically activates lattice and adsorbed oxygen for efficient glycerol electrooxidation

Abstract

Replacing the kinetically sluggish oxygen evolution reaction (OER) with the thermodynamically more favorable glycerol electrooxidation reaction (GOR) has emerged as a promising strategy to enhance the energy efficiency of hydrogen production via water electrolysis. However, selectively converting glycerol to formic acid (FA) remains challenging, as significant kinetic barriers and complex reaction pathways impede efficient C−H/C−C bond cleavage and product selectivity. Herein, a dual-vacancy Dv-CuCoOOH electrocatalyst was successfully constructed through hydrothermal synthesis combined with a vanadium-leaching strategy. Benefiting from the abundant vacancy defects, the optimal Dv-CuCoOOH electrocatalyst achieves a high current density of 400 mA cm−2 together with an FA yield of 91.2% and a Faradaic efficiency (FE) of 96.2% at a relatively low potential of 1.34 VRHE, while reaching 10 mA cm−2 at only 1.05 VRHE. This performance markedly outcompetes the single-defect Ov-CuCoOOH (FA yield of 48.1%, FE of 58.3%), demonstrating the critical role of dual-vacancy engineering. Comprehensive studies reveal that the dual-vacancy defects regulate distinct reactive oxygen species through complementary pathways. Metal vacancies (Mv) facilitate the formation of CoOOH active phases that activate lattice oxygen to promote C–H bond cleavage, while oxygen vacancies (Ov) generate adsorbed oxygen species that facilitate C–C bond cleavage. This work provides a powerful guidance for designing advanced electrocatalysts via dual-vacancy defect engineering.