Activating oxygen on nickel (oxy)hydroxide to promote electrochemical oxidative dehydrogenation of organic molecules

Electrochemical oxidative dehydrogenation (ODH) of organic molecules is emerging as a sustainable alternative to conventional approaches for chemical manufacturing, but the slow production rate of these reactions remains a key challenge. Here we report the selective leaching of vanadium ion (V) in NiV-layered double hydroxide to generate metal vacancy enriched Ni(OH)2 (VM-Ni(OH)2), which exhibits significant improvement in electrochemical ODH of alcohols/aldehydes and primary amines. Experiments and calculations demonstrated that metal vacancies in the catalyst increase the redox activity of oxygen in Ni−O motifs to accept electrons and hydrogen atoms, thus accelerating nucleophilic ODH of organic molecules. Furthermore, we showcased the ODH of biomass-derived 5-hydroxymethylfurfural at current density of 1.5 A cm−2 in a continuous-flow electrolyzer with electrode area of 200 cm2, producing 2,5-furandicarboxylic acid at rate of 1420 mmol h−1 over VM-Ni(OH)2. In contrast to the previously proposed role of V-doping, our findings highlight the critical role of metal vacancies in promoting organic electrooxidation, thereby providing fundamental understanding for the design of more active electrocatalysts.