Electric Field Effects in Electrochemical CO₂ Reduction

TLDR

Electrochemical CO₂ reduction can reduce greenhouse gases, provide energy storage, and produce chemical feedstocks, but a mechanistic understanding of the complex electrochemical interface is essential for efficient catalyst discovery. The study investigates the CO₂‑to‑CO electrocatalytic pathway on Ag(111) using DFT and an explicit electrochemical interface model. The authors employ DFT calculations and an explicit interface model to develop a microkinetic model that incorporates field effects and ab initio electrochemical barriers. The electric field from solvated cations and image charges stabilizes key intermediates (*CO₂ and *COOH), making *CO formation rate‑determining, and the resulting model predicts polarization curves that agree with experiment without fitting parameters.

Abstract

Electrochemical reduction of CO2 has the potential to reduce greenhouse gas emissions while providing energy storage and producing chemical feedstocks. A mechanistic understanding of the process is crucial to the discovery of efficient catalysts, and an atomistic description of the electrochemical interface is a major challenge due to its complexity. Here, we examine the CO2 → CO electrocatalytic pathway on Ag(111) using density functional theory (DFT) calculations and an explicit model of the electrochemical interface. We show that the electric field from solvated cations in the double layer and their corresponding image charges on the metal surface significantly stabilizes key intermediates—*CO2 and *COOH. At the field-stabilized sites, the formation of *CO is rate-determining. We present a microkinetic model that incorporates field effects and electrochemical barriers from ab initio calculations. The computed polarization curves show reasonable agreement with experiment without fitting any parameters.