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Bi-Functional Iron-Only Electrodes for Efficient Water Splitting with Enhanced Stability through in Situ Electrochemical Regeneration

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Martindale, BCM 


jats:pScalable and robust electrocatalysts are required for the implementation of water splitting technologies as a globally applicable means of producing affordable renewable hydrogen. It is demonstrated that iron‐only electrode materials prove to be active for catalyzing both proton reduction and water oxidation in alkaline electrolyte solution with superior activity to that of previously established bi‐functional catalysts containing less abundant elements. The reported bi‐functionality of the iron electrodes is reversible upon switching of the applied bias through electrochemical interconversion of catalytic species at the electrode surface. Cycling of the applied bias results in in‐situ electrochemical regeneration of the catalytic surfaces and thereby extends the catalyst stability and lifetime of the water electrolyzer. Full water splitting at a current density of jats:italicI</jats:italic> = 10 mA cmjats:sup−2</jats:sup> is achieved at a bias of ≈2 V, which is stable over at least 3 d (72 one hour switching cycles). Thus, potential‐switching is established as a possible strategy of stabilizing electrode materials against degradation in symmetrical water splitting systems.</jats:p>



electrocatalysis, charge transport, electrodes, hydrogen, water splitting

Journal Title

Advanced Energy Materials

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Engineering and Physical Sciences Research Council (EP/H00338X/2)
The author’s thank the Oppenheimer Fund (University of Cambridge), the EPSRC (Grant EP/H00338X/2), the Christian Doppler Research Association (Austrian Federal Ministry of Science, Research and Economy and National Foundation for Research, Technology and Development) and OMV Group for financial support. We also thank the National EPSRC XPS User’s Service (NEXUS) at Newcastle University, UK, where XPS spectra were obtained. Dr Chia-Yu Lin is acknowledged for his invaluable help in initial experiments.