ChemRxiv
These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
1/1
2 files

Solvation-Induced Onsager Reaction Field Rather than Double Layer Field Controls CO2 Reduction on Gold

preprint
submitted on 14.04.2021, 02:37 and posted on 15.04.2021, 08:28 by quansong zhu, Spencer Wallentine, Ganghua Deng, L. Robert Baker

The selectivity and activity of the carbon dioxide reduction reaction (CO2R) are sensitive functions of the electrolyte cation. By measuring the vibrational Stark shift of in-situ generated CO on Au in the presence of alkali cations, we quantify the total electric field present during turnover and deconvolute this field into contributions from 1) the electrochemical Stern layer and 2) the Onsager, or solvation-induced, reaction field. The magnitude of the Onsager field is shown to be on the same order as the Stern layer field (∼10 MV/cm) but follows an opposite trend with cation, increasing from Li+< Na+< K+< Rb+≈Cs+. Contrary to theoretical reports,CO2R kinetics are not correlated with the Stern field but instead are controlled by the strength of the Onsager reaction field with Cs+ as an exception. Spectra of interfacial water as a function of cation show that Cs+ induces a change in the interfacial water structure correlated with a dramatic drop in CO2R activity, highlighting the importance of cation-dependent interfacial water structure on reaction kinetics. These findings show that both the Onsager reaction field and interfacial solvation structure must be explicitly considered for accurate modeling of CO2R reaction kinetics.


Funding

SusChEM: CO2 Photo-Electrochemistry on Metal Oxides Surfaces Studied by Vibrational Sum Frequency Generation Spectroscopy and Density Functional Theory

Directorate for Mathematical & Physical Sciences

Find out more...

History

Email Address of Submitting Author

wallentine.1@osu.edu

Institution

Ohio State University

Country

United States

ORCID For Submitting Author

0000-0001-5539-018X

Declaration of Conflict of Interest

The authors declare no conflict of interest.

Version Notes

Cation_Version1

Exports