Dual-metal heterogeneous electrode enabling efficient co-electrosynthesis of adipic acid and hydrogen

Abstract

The electrochemical oxidation of cyclohexanone to produce adipic acid (AA), coupled with hydrogen (H₂) production, represents a promising strategy. However, the development of low-cost and high-performance electrodes remains a significant challenge. Herein, we present Ni@Cu dual-metal heterogeneous material as a proof of concept, demonstrating its potential for efficient co-electrosynthesis of adipic acid and H₂. The Ni@Cu material, featuring abundant heterogeneous interfaces, is grown on copper foam (CF) through a straightforward electrochemical reconstitution strategy. This approach enhances the exposure of catalytic active sites, improves interfacial charge transfer, and accelerates reaction kinetics during electrolysis. As a result, the Ni@Cu/CF electrode achieves low potentials of −172 mV vs. RHE and 1.55 V vs. RHE at 100 mA cm⁻² for the hydrogen evolution reaction (HER) and cyclohexanone oxidation reaction (COR), respectively. The assembled HER||COR electrolyzer delivers a high adipic acid yield (1.15 mmol h⁻¹ at 250 mA cm⁻²) and a maximum Faradaic efficiency (FE) of 88 % at 100 mA cm⁻². It also achieves a high FE for H₂ (over 96 % at 250 mA cm⁻²) and demonstrates excellent co-electrolysis stability for over 100 h. In-situ spectroscopy confirms that the formation of heterogeneous Ni@Cu facilitates the generation of active species and accelerates their kinetic transformation into adipic acid.