(450c) Electric Field Effects on the Structure and Reactivity of Electrocatalytic Interfaces

The applied potential has a significant impact on interfacial structure and reactivity during electrocatalysis. Theoretical modeling can be used to quantify local electric fields and gain atomistic insights into potential-dependent structure and reactivity at the electrode–electrolyte interface. Herein, first-principles density functional theory (DFT) calculations are applied to studies of proton-coupled electron transfer and adsorbate reorientation on electrode surfaces. In an analysis of organic acids electronically conjugated to carbon electrode surfaces, DFT calculations demonstrate that inhomogeneous local electric fields drive heterogeneous surface reactions. Constant-charge and constant-potential DFT approaches yield thermodynamic predictions in close agreement with experimentally measured proton-coupled redox potentials. Next, constant-potential DFT calculations paired with a classical electrolyte model are used to explore the potential-dependent adsorption structure of L-cysteine on Au(111) electrodes. These calculations elucidate the effects of electrode surface charge and electrolyte ionic strength on adsorbate configurations and ion structuring at the electrode–electrolyte interface. These studies provide fundamental insights into the effects of applied potential on the structure and reactivity of electrochemical interfaces.