ELECTROPHOBIC · HydroPHOBIC solvation at ELECTROchemical interfaces

The last two decades have seen an explosion of scientific interest in hydrophobic solvation due to its stunning importance for biology, catalysis and environmental science. However, it is only recently that we realized how important hydrophobicity is for electrochemical interfaces. There, hydrophobic molecules are involved in key electrochemical reactions, such as water splitting and CO2 reduction for renewable energy technologies. Identifying and predicting hydrophobic solvation contributions to thermodynamics is expected to advance our comprehension of these processes, unlocking new ways to improve their efficiency. This can only be achieved through a substantial advance in theoretical understanding. The Lum-Chandler-Weeks theory that revolutionized our comprehension of hydrophobic solvation does not hold true at electrochemical interfaces. A change of paradigms is needed: first, the present theory is based on density fluctuations in the liquid bulk, but these are modulated by surface and applied potential at the interface; second, it is not only the solute size, but a combination of size/shape/position that matters at the interface. Developing a theoretical model from these new paradigms is the challenge tackled by ELECTROPHOBIC. The breakthrough will be to predict hydrophobic contributions to many electrochemical processes with my model. To start, I will focus on how hydrophobic solvation contributes to two problems that currently plague water splitting and CO2 reduction at metal-aqueous interfaces: the undesired aggregation of H2 molecules into interfacial bubbles and the selectivity toward multi-carbon products, respectively. Tremendous advances in the theoretical understanding of these reaction mechanisms and on the role of the electrode catalyst have been made by density functional theory calculations. I will couple these calculations with my model in a hybrid scheme such that surface and solvation contributions are simultaneously but separately evaluated.