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Reversible and Selective CO 2 to HCO 2 − Electrocatalysis near the Thermodynamic Potential
Author(s) -
Cunningham Drew W.,
Barlow Jeffrey M.,
Velazquez Reyna S.,
Yang Jenny Y.
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201913198
Subject(s) - overpotential , faraday efficiency , catalysis , electrocatalyst , chemistry , kinetic energy , thermodynamics , gibbs free energy , energy transformation , electrode , electrochemistry , organic chemistry , physics , quantum mechanics
Reversible catalysis is a hallmark of energy‐efficient chemical transformations, but can only be achieved if the changes in free energy of intermediate steps are minimized and the catalytic cycle is devoid of high transition‐state barriers. Using these criteria, we demonstrate reversible CO 2 /HCO 2 − conversion catalyzed by [Pt(depe) 2 ] 2+ (depe=1,2‐ bis (diethylphosphino)ethane). Direct measurement of the free energies associated with each catalytic step correctly predicts a slight bias towards CO 2 reduction. We demonstrate how the experimentally measured free energy of each step directly contributes to the <50 mV overpotential. We also find that for CO 2 reduction, H 2 evolution is negligible and the Faradaic efficiency for HCO 2 − production is nearly quantitative. A free‐energy analysis reveals H 2 evolution is endergonic, providing a thermodynamic basis for highly selective CO 2 reduction.