Metal vacancy-enriched layered double hydroxide for biomass molecule electrooxidation coupled with hydrogen production

The electrochemical oxidation of biomass molecules coupling with hydrogen production is a promising strategy to obtain both green energy and value-added chemicals; however, this strategy is limited by the competing oxygen evolution reactions and high energy consumption. Herein, we report a hierarchical CoNi layered double hydroxides (LDHs) electrocatalyst with abundant Ni vacancies for the efficient anodic oxidation of 5-hydroxymethylfurfural (HMF) and cathodic hydrogen evolution. The unique hierarchical nanosheet structure and Ni vacancies provide outstanding activity and selectivity toward several biomass molecules because of the finely regulated electronic structure and highly-exposed active sites. In particular, a high faradaic efficiency (FE) at a high current density (99% at 100 mA cm⁻²) is achieved for HMF oxidation, and a two-electrode electrolyzer is assembled based on the Ni vacancies-enriched LDH, which realized a continuous synthesis of highly-pure 2,5-furandicarboxylic acid products with high yields (95%) and FE (90%).