Synergistic Effects of Carbon Supports and Noble Metal Catalysts on the Electrocatalytic Hydrogenation of Phenol to KA Oil

Electrocatalytic hydrogenation (ECH) of phenol to cyclohexanone and cyclohexanol (collectively termed KA oil) offers a green alternative to traditional thermal catalytic hydrogenation (TCH). ECH enables efficient synthesis under mild conditions with enhanced safety and sustainability. This study investigates the influence of different carbon-based supports (carbon paper, carbon cloth, and carbon felt) and noble metal catalysts (Ru, Rh, Pd, Ir, and Pt) on the ECH performance for the conversion of phenol to KA oil. Carbon paper-supported Rh/C (Rh/C/CP) exhibited superior activity, achieving a phenol conversion of 97.4%, a KA oil selectivity of 100% at −500 mV in a 0.5 M H2SO4 solution. This high performance is attributed to the support’s high graphitization, low defect density, and uniform catalyst dispersion, which collectively enhance charge transfer and active site accessibility. In situ Raman spectroscopy elucidated the adsorption and transformation mechanisms of phenol and its intermediates and revealed Rh/C/CP’s optimized balance of hydrogen and phenol adsorption. Systematic optimization of catalyst loading and applied potential further improved the ECH efficiency. This work provides theoretical and experimental insights into designing selective and efficient ECH catalysts and highlights their potential for sustainable conversion of biomass-derived compounds.