Defect-engineered NiCo hydroxide nanostructures for highly efficient electrocatalytic glucose oxidation to formic acid

Abstract

Coupling electrocatalytic hydrogen production with glucose oxidation to value-added oxygenates enables energy-efficient and cost-effective hydrogen generation with enhanced practicality. However, rationally regulating the surface defect structure of electrocatalysts to improve catalytic performance still remains a great challenge. Herein, we design a NiCo layered double hydroxide (D-NiCo(OH)_x) catalyst with abundant oxygen vacancies (V_O) and metal vacancies (V_M) through a one-step hydrothermal method coupled with an alkaline treatment strategy. The as-synthesized D-NiCo(OH)_x catalyst exhibits excellent glucose oxidation reaction (GOR) performance, achieving a current density of 200 mA cm⁻² at 1.33 V (vs. RHE) with a formic acid (FA) faradaic efficiency (FE) of 92% at 1.36 V (vs. RHE), significantly outperforming the low-defect NiCo(OH)_x catalyst (200 mA cm⁻² at 1.45 V (vs. RHE) and a FE(FA) of 79% at 1.36 V (vs. RHE)) and superior to most previously reported non-noble metal electrocatalysts. Systematic studies reveal that dual vacancies enhance substrate adsorption while V_O promotes C–C bond cleavage, collectively optimizing reaction kinetics and accounting for the excellent catalytic performance. This work provides new insights into the synergy of dual vacancies for enhancing substrate adsorption and accelerating C–C bond cleavage, advancing its application in biomass valorization and hydrogen production.