Unravelling the electrochemical double layer by direct probing of the solid/liquid interface

Marco Favaro; Beomgyun Jeong; Philip N Ross; Junko Yano; Zahid Hussain; Zhi Liu; Ethan J Crumlin

doi:10.1038/ncomms12695

Unravelling the electrochemical double layer by direct probing of the solid/liquid interface

Nat Commun. 2016 Aug 31:7:12695. doi: 10.1038/ncomms12695.

Authors

Marco Favaro^{1

2

3}, Beomgyun Jeong^{1

4

5}, Philip N Ross⁶, Junko Yano^{2

7}, Zahid Hussain¹, Zhi Liu^{1

8

9}, Ethan J Crumlin^{1

10}

Affiliations

¹ Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA.
² Joint Center for Artificial Photosynthesis, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA.
³ Chemical Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA.
⁴ Ertl Center for Electrochemistry and Catalysis, School of Environmental Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea.
⁵ Center for Advanced X-ray Science, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea.
⁶ Materials Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA.
⁷ Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA.
⁸ State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, People's Republic of China.
⁹ Division of Photon Science and Condensed Matter Physics, School of Physical Science and Technology, ShanghaiTech University, Shanghai 200031, China.
¹⁰ Joint Center for Energy Storage Research, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, USA.

Abstract

The electrochemical double layer plays a critical role in electrochemical processes. Whilst there have been many theoretical models predicting structural and electrical organization of the electrochemical double layer, the experimental verification of these models has been challenging due to the limitations of available experimental techniques. The induced potential drop in the electrolyte has never been directly observed and verified experimentally, to the best of our knowledge. In this study, we report the direct probing of the potential drop as well as the potential of zero charge by means of ambient pressure X-ray photoelectron spectroscopy performed under polarization conditions. By analyzing the spectra of the solvent (water) and a spectator neutral molecule with numerical simulations of the electric field, we discern the shape of the electrochemical double layer profile. In addition, we determine how the electrochemical double layer changes as a function of both the electrolyte concentration and applied potential.

Publication types

Research Support, Non-U.S. Gov't