Vaso Tileli1
EPFL1
The design of active and stable oxygen-evolving oxide catalysts can be aided by their real-time probing, which provides information on how the catalysts perform and evolve under operating conditions [1]. Among the operando characterization techniques applied to electrocatalysis, electrochemical liquid-phase transmission electron microscopy (ec-LPTEM) is capable of visualizing the electrochemically induced processes in liquid environments at the single particle level. In this talk, I will discuss the progress made in the application of ec-LPTEM for monitoring solid-liquid interface processes occurring on Co-based and iridium oxide OER catalysts [2,3]. By analyzing the contrast of the lateral liquid electrolyte surrounding the catalyst particle in TEM images, the surface wetting dynamics with respect to the applied potential is revealed. The overall decrease in the lateral liquid thickness indicates a switch from hydrophobic to hydrophilic character under anodic potential due to electrowetting induced by ion accumulation at the interface. Within the pre-OER potential, the change in the surface wetting behavior on Co-based oxides suggests a link to the underlying Co II/III redox reaction and surface transformation of the oxyhydroxide phase. I will also demonstrate the direct probing of electrocatalytic molecular oxygen using operando electron energy-loss spectroscopy (EELS). Progress toward facet selectivity probing of the evolving molecular oxygen will be discussed and evidence of highly-pressurized electrocatalytic gas formation in the microcells will be presented.<br/><br/>References<br/>[1] J. T. Mefford et al., Nature <b>593</b>, 67 (2021)<br/>[2] T.-H. Shen, L. Spillane, J. Peng, Y. Shao-Horn, and V. Tileli, Nature Catalysis <b>5</b>, 30 (2022)<br/>[3] T. -H. Shen, R. Girod, J. Vavra, and V. Tileli, The Journal of The Electrochemical Society <b>170</b>, 056502 (2023)