Interface coupling induced electronic effect of NiCo-LDH/Cu2O heterojunction catalysts towards efficient electrochemical nitrate reduction to ammonia

Abstract

The electrocatalytic nitrate reduction reaction to ammonia (NO₃RR) can reduce pollution and conserve energy, but current catalyst activity still fails to meet production requirements, primarily due to insufficient atomic hydrogen (H*) supply and slow hydrogenation of oxynitride intermediates. This work leverages the strong nitrate adsorption capability of cuprous oxide (Cu₂O) and interfacial coupling between NiCo layered double hydroxides (NiCo-LDH) and Cu₂O to fabricate a nanocomposite catalyst (NiCo-LDH/Cu₂O) via a facile hydrothermal method. By adjusting the metal ratio to modulate proton absorption behavior, the NiCo-LDH/Cu₂O catalyst can achieve high ammonia yield (0.382 mmol h⁻¹ cm⁻²) and desired Faraday efficiency (80.4%). The experimental results demonstrate that the interfacial coupling interaction between NiCo-LDH and Cu₂O induces optimal electronic effects, and then promotes the adsorption and activation of reaction intermediates, as well as optimizes the reaction pathway, and significantly enhances the electrochemical ammonia synthesis performance. Our constructed NiCo-LDH/Cu₂O catalysis system provides a feasible strategy for the development of efficient and cost-effective NO₃RR applications.