Looking below the surface: probing electrochemical and catalytic reactions under real-world conditions

Probing the chemical reactions occurring at electrochemical and catalytic interfaces is critical to selecting and designing improved materials for energy storage, corrosion prevention, and chemical synthesis.

Soft X-ray spectroscopies can provide powerful element- and chemical-state-specific information with the required nanometer-scale interface sensitivity, but have traditionally required high vacuum conditions, impeding studies of interfaces under realistic liquid- and gas-phase environments.

I will introduce several membrane-based approaches we have developed over recent years to bridge this pressure gap, enabling operando x-ray photoelectron and absorption spectroscopy (XPS/XAS) of solid-liquid and solid-gas interfaces at atmospheric pressures and above.

These rely on reaction environments sealed with X-ray/electron-transparent membranes, that can sustain large pressure drops to the high-vacuum measurement chamber. I will show how these membrane-based approaches can be applied to study the chemical evolution of electrode-electrolyte interfaces in Li-ion batteries, and catalyst nanoparticles in atmospheric pressure environments.

I will also give a perspective on future directions that will enable these techniques to be extended to ever more realistic materials systems and operating conditions.

Rob Weatherup has recently joined the Department of Materials in Oxford as an Associate Professor in energy materials.

His group develops interface sensitive characterisation techniques to understand the interfacial processes involved in the synthesis and operation of materials in areas including electrochemical energy storage, heterogeneous catalysis, and electronic devices.

Much of this work involves the use of international synchrotron facilities, and he has worked closely with these facilities over the last decade to extend various X-ray spectroscopy techniques to the study of materials in realistic working environments.