Proton–electron synergistic transport in nickel–Iron layered double hydroxide decorated Cu/Cu₂O heterostructure for electrocatalytic nitrate reduction to ammonia

A self-supporting hierarchical NiFe-LDH@Cu/Cu 2 O heterostructure has been designed. • The tightly coupled NiFe-LDH@Cu/Cu 2 O heterointerface achieves efficient proton-electron synergistic transfer. • The catalyst delivers NO 3 − reduction performance with high Faradaic efficiency and excellent selectivity toward NH 3 . Electrochemical nitrate reduction reaction (NO 3 RR) provides a sustainable approach for ammonia synthesis and environmental remediation; however, the multi-step proton-coupled electron transfer processe poses significant challenges for achieving high efficiency and selectivity. Herein, we engineered a self-supporting NiFe-LDH@Cu/Cu 2 O (LDH: layered double hydroxides) heterostructure via facile hydrothermal and electrochemical deposition methods. The optimized electrode delivers exceptional NH 3 synthesis performance (1.06 ± 0.058 mmol h −1  cm −2 and a Faraday efficiency of 97.6 ± 1.88% at −0.4 V vs. RHE) and an excellent long-term stability. The experimental and theoretical calculation results reveal that NiFe-LDH accelerates water dissociation to yield abundant active hydrogen (*H) species, relieving the *H shortage during the reaction. The Schottky interface of Cu/Cu 2 O further optimizes interfacial electronic configuration, facilitates electron transport, and strengthens the adsorption of NO 3 − and reaction intermediates. The tightly coupled NiFe-LDH@Cu/Cu 2 O heterointerface realizes a highly efficient proton-electron synergistic relay. This distinctive effect drives the coordinated transport of electrons and protons, maximizes the utilization of active hydrogen, and expedites the deep hydrogenation of NO 2 − intermediates. This work provides a rational design strategy for enhancing NO 3 RR performance toward waste nitrate treatment and green ammonia synthesis via proton-electron coupled transfer engineering. Download: Download high-res image (250KB) Download: Download full-size image