Efficient electrocatalytic water oxidation at neutral and high pH by adventitious nickel at nanomolar concentrations

Roger, I. and Symes, M. D. (2015) Efficient electrocatalytic water oxidation at neutral and high pH by adventitious nickel at nanomolar concentrations. Journal of the American Chemical Society, 137(43), pp. 13980-13988. (doi: 10.1021/jacs.5b08139) (PMID:26477432)

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Electrolytic water oxidation using earth-abundant elements is a key challenge in the quest to develop cheap, large surface area arrays for solar-to-hydrogen conversion. There have been numerous studies in this area in recent years, but there remains an imperative to demonstrate that the current densities reported are indeed due to the species under consideration and not due to the presence of adventitious (yet possibly highly active) contaminants at low levels. Herein, we show that adventitious nickel at concentrations as low as 17 nM can act as a water oxidation catalyst in mildly basic aqueous solutions, achieving stable (tens of hours) current densities of 1 mA cm–2 at overpotentials as low as 540 mV at pH 9.2 and 400 mV at pH 13. This nickel was not added to the electrolysis baths deliberately, but it was found to be present in the electrolytes as an impurity by ICP-MS. The presence of nickel on anodes from extended-time bulk electrolysis experiments was confirmed by XPS. In showing that such low levels of nickel can perform water oxidation at overpotentials comparable to many recently reported water oxidation catalysts, this work serves to raise the burden of proof required of new materials in this field: contamination by adventitious metal ions at trace loadings must be excluded as a possible cause of any observed water oxidation activity.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Symes, Professor Mark
Authors: Roger, I., and Symes, M. D.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Journal of the American Chemical Society
Publisher:American Chemical Society
ISSN (Online):1520-5126
Copyright Holders:Copyright © 2015 American Chemical Society
First Published:First published in Journal of the American Chemical Society 137(43):13980-13988
Publisher Policy:Reproduced under a Creative Commons License
Data DOI:10.5525/gla.researchdata.227

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
621311Upgrading the small scale equipment base for early career researchers in the engineering and physical sciencesMiles PadgettEngineering & Physical Sciences Research Council (EPSRC)EP/K031732/1S&E P&A - PHYSICS & ASTRONOMY