The presence of water has been shown to enhance hydrogenation of polar chemical functional groups, such as C=O and N=O bonds, through proton shuttling. To demonstrate such rather sophisticated reaction pathways, explicit solvent models with dynamic change of local solvent structures should be considered. Beyond what we reported previously for water-promoted C=O hydrogenation in furfural, in this work, we highlight the proton shuttling mechanism can also be applied to C=C hydrogenation at solid-liquid interfaces in the presence of bifunctional metal-acid sites containing boric acid adsorbed on Ni(111) surface. Our calculations show that the dynamic transformation of this metal-acid interface can promote hydrogenation of the C=C bond in cyclohexene. In experiments, a rate enhancement by more than 100 times has been observed when adding small amount of water into an organic solvent. According to our atomic models, dynamic formation of a B(OH)3-H2O complex is crucial for lowering the activation barrier of the first hydrogenation. Our findings thus provide fundamental insights of this dynamic transformation at the solid-liquid interface and its impact on catalytic activity and selectivity.
