Theoretical Investigations of the Electrochemical Reduction of CO on Single Metal Atoms Embedded in Graphene

Charlotte Kirk, Leanne D. Chen, Samira Siahrostami, Mohammadreza Karamad, Michal Bajdich, Johannes Voss, Jens K. Nørskov, K. Chan

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Single transition metal atoms embedded at single vacancies of graphene provide a unique paradigm for catalytic reactions. We present a density functional theory study of such systems for the electrochemical reduction of CO. Theoretical investigations of CO electrochemical reduction are particularly challenging in that electrochemical activation energies are a necessary descriptor of activity. We determined the electrochemical barriers for key proton-electron transfer steps using a state-of-the-art, fully explicit solvent model of the electrochemical interface. The accuracy of GGA-level functionals in describing these systems was also benchmarked against hybrid methods. We find the first proton transfer to form CHO from CO to be a critical step in C1 product formation. On these single atom sites, the corresponding barrier scales more favorably with the CO binding energy than for 211 and 111 transition metal surfaces, in the direction of improved activity. Intermediates and transition states for the hydrogen evolution reaction were found to be less stable than those on transition metals, suggesting a higher selectivity for CO reduction. We present a rate volcano for the production of methane from CO. We identify promising candidates with high activity, stability, and selectivity for the reduction of CO. This work highlights the potential of these systems as improved electrocatalysts over pure transition metals for CO reduction.

Original languageEnglish
JournalACS Central Science
Volume3
Issue number12
Pages (from-to)1286-1293
Number of pages8
ISSN2374-7943
DOIs
Publication statusPublished - 2017
Externally publishedYes

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