Jump to main content
Jump to site search

Issue 24, 2016
Previous Article Next Article

Partial oxidation of step-bound water leads to anomalous pH effects on metal electrode step-edges

Author affiliations

Abstract

The design of better heterogeneous catalysts for applications such as fuel cells and electrolyzers requires a mechanistic understanding of electrocatalytic reactions and the dependence of their activity on operating conditions such as pH. A satisfactory explanation for the unexpected pH dependence of electrochemical properties of platinum surfaces has so far remained elusive, with previous explanations resorting to complex co-adsorption of multiple species and resulting in limited predictive power. This knowledge gap suggests that the fundamental properties of these catalysts are not yet understood, limiting systematic improvement. Here, we analyze the change in charge and free energies upon adsorption using density-functional theory (DFT) to establish that water adsorbs on platinum step edges across a wide voltage range, including the double-layer region, with a loss of approximately 0.2 electrons upon adsorption. We show how this as-yet unreported change in net surface charge due to this water explains the anomalous pH variations of the hydrogen underpotential deposition (Hupd) and the potentials of zero total charge (PZTC) observed in published experimental data. This partial oxidation of water is not limited to platinum metal step edges, and we report the charge of the water on metal step edges of commonly used catalytic metals, including copper, silver, iridium, and palladium, illustrating that this partial oxidation of water broadly influences the reactivity of metal electrodes.

Graphical abstract: Partial oxidation of step-bound water leads to anomalous pH effects on metal electrode step-edges

Back to tab navigation

Publication details

The article was received on 10 Mar 2016, accepted on 26 May 2016 and first published on 26 May 2016


Article type: Paper
DOI: 10.1039/C6CP01652A
Citation: Phys. Chem. Chem. Phys., 2016,18, 16216-16223
  • Open access: Creative Commons BY-NC license
  •   Request permissions

    Partial oxidation of step-bound water leads to anomalous pH effects on metal electrode step-edges

    K. Schwarz, B. Xu, Y. Yan and R. Sundararaman, Phys. Chem. Chem. Phys., 2016, 18, 16216
    DOI: 10.1039/C6CP01652A

    This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material and it is not used for commercial purposes.

    Reproduced material should be attributed as follows:

    • For reproduction of material from NJC:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS) and the RSC.
    • For reproduction of material from PCCP:
      [Original citation] - Published by the PCCP Owner Societies.
    • For reproduction of material from PPS:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC.
    • For reproduction of material from all other RSC journals:
      [Original citation] - Published by The Royal Society of Chemistry.

    Information about reproducing material from RSC articles with different licences is available on our Permission Requests page.

Search articles by author

Spotlight

Advertisements