Potential of zero charge and surface charging relation of metal-solution interphases from a constant-potential jellium-Poisson-Boltzmann model

Jun Huang, Peng Li, and Shengli Chen
Phys. Rev. B 101, 125422 – Published 23 March 2020

Abstract

The potential of zero charge (pzc), a fundamental concept in interfacial electrochemistry, is revisited using a jellium-Poisson-Boltzmann model. Under constant-potential description of the metal-solution interphase, this model is able to calculate the surface charging relation (surface free charge density as a function of the electrode potential) and then to determine the pzc therefrom. The potential corresponding to the minimum of differential double-layer capacitance curve is shown to be lower than the pzc determined from surface charging relation, which is caused by free metal electrons entering the solution phase. The model further reveals that the pzc decreases when the vacuum gap between the solution phase and the metal surface, d, becomes narrower. This is consistent with the common observation that the pzc of metal-solution interphase is lower than that calculated from the work function of metal-vacuum interphase (the latter corresponds to d=). Multifaceted roles played by the solvent, including electrostatic screening, polaron effect, and orthogonalizational repulsion, are analyzed. Also discussed are the effects of specific adsorption of ions and potential-dependent d on the surface charging relation.

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  • Received 20 June 2019
  • Revised 22 February 2020
  • Accepted 26 February 2020

DOI:https://doi.org/10.1103/PhysRevB.101.125422

©2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Jun Huang1,*, Peng Li2, and Shengli Chen2,†

  • 1Hunan Provincial Key Laboratory of Chemical Power Sources, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China
  • 2Hubei Key Laboratory of Electrochemical Power Sources, Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072, China

  • *jhuangelectrochem@qq.com
  • slchen@whu.edu.cn

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Vol. 101, Iss. 12 — 15 March 2020

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