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 electrocatalyst to improve the 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) performances, 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), which is much higher than that of NiCo-LDH without defects (denoted as NiCo(OH)_x) 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.