Defect-Engineered Interfacial Water Structure for Enhanced Solar-Driven Electrooxidation of KA Oil.

Abstract

Cyclohexanol electrooxidation reaction (CHAOR) offers a sustainable route for producing adipic acid. However, achieving high ring-opening efficiency and stable long-term yield remains challenging due to limited understanding of active oxygen species and reaction pathway. In this study, Ru single atoms and oxygen vacancies are used to construct a synergistic interface for efficient CHAOR. Oxygen vacancies serve as structural promoters by creating Lewis acid sites that enhance organic species adsorption and mitigate the agglomeration of Ru atoms. Atomically dispersed Ru sites act as functional modulators by disrupting the interfacial hydrogen-bond network-as confirmed by in situ Raman-to lower the *OH formation barrier and facilitate the accessibility of organic molecules to the catalytic surface, as supported by quartz crystal microbalance experiments and density functional theory calculations. The tandem electrochemical-chemical mechanism is elucidated: *OH formation is the electrochemical step, while its reaction with organics is the chemical step. Benefiting from the synergy, Ru-NiOx achieves 100% conversion and 87% AA (adipic acid) yield at 1.45 VRHE. Furthermore, a photovoltaic-electrolysis system is developed to address solar intermittency and power fluctuations, in which Ru-NiOx exhibits excellent stability over 1000 h with a maximum productivity of 204.4 µmol cm-2 h-1. Scaling to eight electrolyzers demonstrates good scalability, indicating strong potential for practical application.