aam.pdf (5.37 MB)
Download file

In situ observation of the pH gradient near the gas diffusion electrode of CO2 reduction in alkaline electrolyte

Download (5.37 MB)
journal contribution
posted on 19.10.2020, 10:58 authored by Xu Lu, Chongqin Zhu, Zishan Wu, Jin Xuan, Joseph S Francisco, Hailiang Wang
The local pH variation near the surface of CO2 reduction electrodes is important but hard to study. We develop a continuous-flow Raman electrochemical cell that enables the first experimental study of the local pH near a CO2 reduction gas diffusion electrode under reaction conditions. At zero current, CO2 chemically reacts with the 1 M KOH electrolyte at the interface to form HCO3- and CO32-. The local pH on the cathode surface is 7.2, and the HCO3- concentration profile extends a distance of 120 μm into the electrolyte, which verifies that the nominal overpotential reduction from using alkaline electrolyte originates from the Nernst potential of the pH gradient layer at the cathode/electrolyte interface. The CO2-OH- neutralization reaction and the pH gradient layer still persist, albeit to a reduced extent, at CO2 reduction current densities up to 150 mA/cm2.

Funding

National Science Foundation (Grant CHE-1651717)

National Science Foundation (Grant CHE1665324)

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Chemical Engineering

Published in

Journal of the American Chemical Society

Volume

142

Issue

36

Pages

15438 - 15444

Publisher

American Chemical Society (ACS)

Version

AM (Accepted Manuscript)

Rights holder

© American Chemical Society

Publisher statement

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/jacs.0c06779

Publication date

2020-07-21

Copyright date

2020

ISSN

0002-7863

eISSN

1520-5126

Language

en

Depositor

Prof Jin Xuan. Deposit date: 15 October 2020