Cr-Doping Promoted Surface Reconstruction of Ni(OH)2 Electrocatalysts toward Efficient Adipic Acid Electrosynthesis

Electrooxidation offers a sustainable alternative by utilizing renewable energy to convert biomass-derived cyclohexanol (CHA) to adipic acid (AA), a key industrial chemical for nylon-66 and polyurethane production. While bimetallic Ni-based catalysts enhance the conversion, the role of secondary metals in modulating Ni active-site reconstruction during operation remains unclear, limiting performance optimization. Here, we demonstrate that Cr-doping promoted the dynamic reconstruction of Ni(OH)2 nanosheets to form NiOOH with abundant Ni3+ and oxygen vacancies (OVs), significantly boosting AA electrosynthesis. In situ characterizations reveal that Cr-doping accelerates OH– adsorption and promotes NiOOH formation, while subsequent Cr3+ leaching generates OVs, thus, resolving the long-standing dilemma between stabilizing high-valence Ni and maintaining abundant defects. The optimized catalyst achieves 78.1% AA yield and 85.4% Faradaic efficiency at 1.45 V vs RHE, outperforming undoped Ni(OH)2 and prior systems. Mechanistic studies identify surface Ni3+ and OVs-stabilized *OOH species as the keys for CHA dehydrogenation and cyclohexanone oxidation, respectively. Moreover, a membrane electrode assembly electrolyzer was designed for the efficient coproduction of AA (0.078 mmol h–1 cm–2) and H2 (42.9 mL h–1 cm–2) at a current density of 100 mA cm–2, demonstrating the scalability. This work clarifies the in situ reconstruction of bimetallic sites and provides a design strategy for the efficient electrosynthesis.