Molybdenum−Oxygen Species Boost Hydrogen-Adipic Acid Paired Electrosynthesis by Enhancing Water Dissociation Dynamics on Cu−Ni Alloy

Abstract Constructing energy-saving paired electrolysis that couples the electrosynthesis of adipic acid with hydrogen evolution is highly attractive for sustainable energy systems and carbon neutrality. However, achieving highly active bifunctional electrocatalysts capable of accelerating the synergistic reaction kinetics of both half-reactions remains challenging. Herein, we report an oxygen-vacancy-rich molybdenum-oxygen species-modified Cu-Ni alloy (Cu0.81Ni0.19@MoOx), prepared via a simple one-step electrodeposition strategy, as a high-performance bifunctional electrocatalyst for the cyclohexanone oxidation reaction (COR) and hydrogen evolution reaction (HER). The introduction of amorphous MoOx species synergistically enhances catalytic performance by modulating the electronic structure through strong interfacial electronic interactions, promoting alkaline water dissociation to supply reactive intermediates, and boosting the formation of key intermediates. Benefiting from these advantages, the optimized Cu0.81Ni0.19@MoOx catalyst enables efficient membrane-free HER‖COR paired electrolysis, simultaneously delivering a hydrogen Faradaic efficiency above 98.2% and adipic acid production with a high Faradaic efficiency of 94.7% and a rate of 0.88 mmol h−1 cm−2 at 150 mA cm−2, while maintaining stable operation over 288 h and allowing the collection of purified adipic acid products, thus demonstrating a viable strategy for energy-saving co-production of clean fuel and value-added chemicals.