How palladium inhibits CO poisoning during electrocatalytic formic acid oxidation and carbon dioxide reduction

Xiaoting Chen,Ian T Mccrum,Marc T M Koper,Laura P Granda-Marulanda

doi:10.1038/s41467-021-27793-5

Xiaoting Chen, Ian T Mccrum + Show 2 more

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https://doi.org/10.1038/s41467-021-27793-5

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Journal: Nature Communications	Publication Date: Jan 10, 2022
Citations: 55	License type: open-access

Affiliation: Leiden University, Clarkson University

Abstract

Development of reversible and stable catalysts for the electrochemical reduction of CO2 is of great interest. Here, we elucidate the atomistic details of how a palladium electrocatalyst inhibits CO poisoning during both formic acid oxidation to carbon dioxide and carbon dioxide reduction to formic acid. We compare results obtained with a platinum single-crystal electrode modified with and without a single monolayer of palladium. We combine (high-scan-rate) cyclic voltammetry with density functional theory to explain the absence of CO poisoning on the palladium-modified electrode. We show how the high formate coverage on the palladium-modified electrode protects the surface from poisoning during formic acid oxidation, and how the adsorption of CO precursor dictates the delayed poisoning during CO2 reduction. The nature of the hydrogen adsorbed on the palladium-modified electrode is considerably different from platinum, supporting a model to explain the reversibility of this reaction. Our results help in designing catalysts for which CO poisoning needs to be avoided.

Highlights

Development of reversible and stable catalysts for the electrochemical reduction of CO2 is of great interest
In combination with first-principles density functional theory calculations, our studies reveal the crucial role of adsorbed formate anions in inhibiting CO poisoning during formic acid oxidation
The experimental results and the Density functional theory (DFT) calculations indicate that adsorbed formate plays a key role in preventing CO poisoning on the PdMLPt(111) electrode during formic acid oxidation

Summary

Introduction

Development of reversible and stable catalysts for the electrochemical reduction of CO2 is of great interest. We compare results obtained with a platinum single-crystal electrode modified with and without a single monolayer of palladium. We show how the high formate coverage on the palladium-modified electrode protects the surface from poisoning during formic acid oxidation, and how the adsorption of CO precursor dictates the delayed poisoning during CO2 reduction. The nature of the hydrogen adsorbed on the palladium-modified electrode is considerably different from platinum, supporting a model to explain the reversibility of this reaction. Formic acid oxidation on Pt surfaces has been studied extensively and the dual-pathway mechanism[5] has been well established by the community[2] This mechanism assumes that there are two parallel pathways in the reaction scheme. Pd-based catalysts for electrochemical formic acid oxidation generally display high activity and, remarkably, the absence of CO poison formation. Armstrong and Hirst[28] have discussed how redox enzymes can reversibly catalyze the reaction (HCOOH ⇆ CO2 + 2H+ + 2e−)

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