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Seminar - Robert S. Weatherup

Monday 9th September 2019 at 11h00, Robert S. Weatherup (University of Manchester at Harwell, Diamond Light Source, Didcot, Oxfordshire, UK) will give a seminar on "Probing Electrochemical Interfaces Under Working Conditions with X-ray Spectroscopies"

Abstract:
Probing the chemical reactions occurring at electrochemical interfaces under realistic conditions is critical to selecting and designing improved materials for energy storage, chemical production, and corrosion prevention. Soft X-ray spectroscopies offer powerful element- and chemical-state-specific information with the required nm-scale interface sensitivity, but have traditionally required high vacuum conditions, impeding studies of liquid-phase environments [1].
Here we introduce several membrane-based approaches developed in recent years in order to bridge this pressure gap, enabling operando x-ray photoelectron and absorption spectroscopy (XPS/XAS) of solid-liquid interfaces [2–5]. These rely on reaction cells sealed with X-ray/electron-transparent membranes, that can sustain large pressure drops to the high-vacuum measurement chamber [2,3]. Thin (<100 nm) silicon nitride membranes are commercially available and transparent to even soft X-rays, whilst graphene membranes have thicknesses below the inelastic mean free path of photoelectrons (typically < 2 nm) and yet remain highly impermeable to gases and liquids [4]. We show how these membrane-based approaches can be applied to study the chemical evolution of solid-liquid interfaces under electrochemical control, including the oxidation/reduction of Ni electrodes [5], and the solid-electrolyte interphase formation on Li-ion battery anodes. The extension of soft x-ray spectroscopies to liquid environments offered by these approaches is expected to be valuable for the study of a wide range of interfacial reactions across the electrochemical sciences.

[1] Wu et al. Phys. Chem. Chem. Phys. 17, 30229 (2015).
[2] Velasco-Velez et al. Angew. Chemie 54, 14554 (2015).
[3] Weatherup et al. J. Phys. Chem. Lett. 7, 1622 (2016).
[4] Weatherup et al. Top. Catal. 61, 2085 (2018).
[5] Weatherup et al. J. Phys. Chem. B 122, 737 (2018).

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