Hierarchical Ru0/Ruδ+/Al2O3 electrocatalyst enabling phenolic contaminant-to-chemical conversion

Valorizing phenol in wastewater to cyclohexanol via electrochemical hydrogenation (ECH) offers a promising strategy for advancing a circular economy that shifts from pollutant control to resource recovery, but remains challenged by the absence of efficient and selective catalysts in complex wastewater matrices. Herein, we report a hierarchical Ru⁰/Ru^δ+/Al₂O₃ catalyst with coupling multi-level electronic state to improve the phenol ECH performance. The metal-semimetal-insulator hierarchical interface effectively induces the integration of H* evolution and phenol activation, and the unsaturated Ru-O coordination formed by precise anchoring of Ru on Al₂O₃ lowers the reaction energy barrier, achieving a 4.3-fold increase in the reaction rate over that on the pristine Ru catalyst. Consequently, the ECH process applied to actual phenol-containing wastewater demonstrates a stable cyclohexanol selectivity of approximately 80% for over 120 h, making it more economically feasible and environmentally beneficial than the conventional adsorption-Fenton oxidation treatment. Our work provides valuable guidance for wastewater treatment from environmental burden to sustainable recovery.