Voltage-driven molecular catalysis of electrochemical reactions

Heterogeneous electrocatalysis and molecular redox catalysis have developed over the past several decades as two distinct ways to facilitate charge-transfer processes essential for energy conversion and storage. Whereas electrocatalytic reactions are driven by the applied voltage, molecular catalytic processes are driven by the difference between standard potentials of the catalyst and the reactant. Here, we demonstrate that the electrostatic potential drop across the double layer contributes to the driving force for electron transfer between a dissolved reactant and a molecular catalyst (e.g., ferrocene) immobilized directly on the electrode surface. Our density functional theory calculations show that varying the applied voltage alters the potential drop between the surface-bound molecular catalyst and the reactant and in some cases the chemical bonding between them, thereby increasing the reaction rate. These results suggest a promising new route for designing next-generation hybrid molecular/electrocatalysts.