A unifying mechanism for cation effect modulating C1 and C2 productions from CO2 electroreduction
SJ Shin and H Choi and S Ringe and DH Won and HS Oh and DH Kim and T Lee and DH Nam and H Kim and CH Choi, NATURE COMMUNICATIONS, 13, 5482 (2022).
Electrocatalysis, whose reaction venue locates at the catalyst- electrolyte interface, is controlled by the electron transfer across the electric double layer, envisaging a mechanistic link between the electron transfer rate and the electric double layer structure. A fine example is in the CO2 reduction reaction, of which rate shows a strong dependence on the alkali metal cation (M+) identity, but there is yet to be a unified molecular picture for that. Using quantum-mechanics-based atom-scale simulation, we herein scrutinize the M+-coupling capability to possible intermediates, and establish H+- and M+-associated ET mechanisms for CH4 and CO/C2H4 formations, respectively. These theoretical scenarios are successfully underpinned by Nernstian shifts of polarization curves with the H+ or M+ concentrations and the first- order kinetics of CO/C2H4 formation on the electrode surface charge density. Our finding further rationalizes the merit of using Nafion- coated electrode for enhanced C2 production in terms of enhanced surface charge density. CO2 reduction rate shows a strong dependence on alkali metal cation identity but a unified molecular picture for underlying mechanism requires further investigation. Using advanced molecular simulations and experimental kinetic studies, here the authors establish a unified mechanism for cation-coupled electron transfer.
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