Selective Electrochemical Hydrogenation of Phenol with Earth-abundant Ni-MoO2 Heterostructured Catalysts: Effect of Oxygen Vacancy on Product Selectivity

Herein, we report highly efficient carbon supported Ni-MoO2 heterostructured catalysts for the electrochemical hydrogenation (ECH) of phenol in 0.10 M aqueous sulfuric acid (pH 0.7) at 60 degrees C. Highest yields for cyclohexanol and cyclohexanone of 95 % and 86 % with faradaic efficiencies of similar to 50 % are obtained with catalysts bearing high and low densities of oxygen vacancy (O-v) sites, respectively. In situ diffuse reflectance infrared spectroscopy and density functional theory calculations reveal that the enhanced phenol adsorption strength is responsible for the superior catalytic efficiency. Furthermore, 1-cyclohexene-1-ol is an important intermediate. Its hydrogenation route and hence the final product are affected by the O-v density. This work opens a promising avenue to the rational design of advanced electrocatalysts for the upgrading of phenolic compounds.

Automated summary

In this study, highly efficient carbon supported Ni-MoO2 heterostructured catalysts were reported for the electrochemical hydrogenation (ECH) of phenol in 0.10 M aqueous sulfuric acid (pH 0.7) at 60 degrees C. Catalysts with high and low densities of oxygen vacancy (O-v) sites achieved the highest yields of cyclohexanol and cyclohexanone, 95% and 86%, respectively, with faradaic efficiencies of approximately 50%. The enhanced phenol adsorption strength attributed to the O-v density was found to be responsible for the superior catalytic efficiency. This work provides a promising avenue for the rational design of advanced electrocatalysts for the upgrading of phenolic compounds.