Quantifying Hydroxyl Adsorption on Copper with Electrochemical-Aware Random Phase Approximation

Area of Science:

• Computational chemistry
• Surface science
• Electrochemistry

Background:

• Accurate adsorption thermodynamics at electrified metal interfaces are crucial for surface science, catalysis, and electrochemical modeling.
• Standard density functional approximations struggle with these calculations and experimental benchmarking is difficult.

Purpose of the Study:

• To apply electrochemical-aware random phase approximation (RPA) methods for a reference-quality description of hydroxyl (*OH) adsorption on Cu(100) under electrocatalytic conditions.
• To quantify *OH binding at different sites and under applied potential.
• To provide a mechanistic understanding of adsorption thermodynamics.

Main Methods:

• Electrochemical-aware RPA methods incorporating solvent dielectric screening and grand-canonical constant-potential control.
• Analysis of site dependence of *OH binding at the potential of zero charge.
• Comparison with widely used GGA functionals (PBE, RPBE).
• G0W0-RPA electronic structure analysis.

Main Results:

• Electrochemical-aware RPA accurately reproduces experimental *OH desorption fingerprint, predicting a desorption potential of -0.54 V vs SHE.
• GGA functionals underestimate *OH stability and compress the stability window under reducing conditions.
• Many-body accuracy qualitatively alters predicted interfacial speciation for *OH and *CO coadsorption.

Conclusions:

• Electrochemical-aware RPA is established as a broadly applicable, systematically improvable many-body framework for quantitative adsorption thermodynamics at constant potential.
• This method enables predictive surface-state maps for complex electrochemical interfaces.
• It offers a pathway to overcome limitations of standard DFT approximations in electrochemistry.