Nickel-copper alloying arrays realizing efficient co-electrosynthesis of adipic acid and hydrogen

Abstract

Constructing electrocatalytic overall reaction technology to couple the electrosynthesis of adipic acid with energy-saving hydrogen production is of significant for sustainable energy systems. However, the development of highly-active bifunctional electrocatalysts remains a challenge. Herein, 3D hierarchical nickel-copper alloying arrays with dendritic morphology are manufactured by a simple electrodeposition process, standing for the excellent bifunctional electrocatalyst towards the co-production of adipic acid and H₂ from cyclohexanone and water. The membrane-free flow electrolyzer of Cu_0.81Ni_0.19/NF shows the superior electrooxidation performance of ketone-alcohol (KA) oil with high faradaic efficiencies of over 90% for adipic acid and H₂, robust stability over 200 h as well as a high yield of 0.6 mmol h⁻¹ for adipic acid at 100 mA cm⁻². In-situ spectroscopy indicates the Cu_0.81Ni_0.19 alloy contributes to forming more active NiOOH species to involve in the conversion of cyclohexanone to adipic acid, while the proposed reaction pathway undergoes the 2-hydroxycyclohexanone and 2,7-oxepanedione intermediates. Moreover, the theoretical calculations confirm that the optimal electronic interaction, boosted reaction kinetics as well as improved adsorption free energy of reaction intermediates, synergistically endows Cu_0.81Ni_0.19 alloy with superior bifunctional performance.