Towards First-principles Electrochemistry

TL;DR

This paper develops a first-principles electrochemical model to study molecular chemisorption and vibrational frequency shifts at fuel cell electrodes, providing insights into the electrochemical environment and resolving previous experimental controversies.

Contribution

It introduces a comprehensive model for chemisorption at constant charge or voltage and accurately predicts vibrational Stark effects from first principles.

Findings

Predicted vibrational Stark slopes match experimental data

Resolved controversies in interpreting in-situ spectroscopic experiments

Clarified the relation between canonical and grand-canonical descriptions

Abstract

Chemisorbed molecules at a fuel cell electrode are a very sensitive probe of the surrounding electrochemical environment, and one that can be accurately monitored with different spectroscopic techniques. We develop a comprehensive electrochemical model to study molecular chemisorption at either constant charge or fixed applied voltage, and calculate from first principles the voltage dependence of vibrational frequencies -- the vibrational Stark effect -- for CO adsorbed on close-packed platinum electrodes. The predicted vibrational Stark slopes are found to be in very good agreement with experimental electrochemical spectroscopy data, thereby resolving previous controversies in the quantitative interpretation of in-situ experiments and elucidating the relation between canonical and grand-canonicaldescriptions of vibrational surface phenomena.