Operando TEY-STXM—Spectromicroscopy of the Solid-Liquid Interface

Rational design of electrochemically active materials requires a better understanding of the structure and chemistry of solid-liquid interfaces. However, the buried nature of these interfaces makes them especially challenging to probe <i>in-operando</i> with high surface-sensitivity. The use of faceted nanoparticles in practical devices further necessitates the development of <i>operando</i> techniques that combine high spatial resolution with surface sensitivity and chemical specificity.<br/><br/>In this talk, I will discuss our development of <i>operando</i> total electron yield scanning transmission x-ray microscopy (TEY-STXM). This new technique combines the 25 nm spatial resolution of <i>operando</i> STXM¹ with the 3 nm surface-sensitivity of <i>operando</i> TEY-XAS,² enabling simultaneous spectromicroscopy of the surface and bulk of electrochemically active materials under reaction conditions. Beyond the solid, <i>operando</i> TEY-STXM enables spatially resolved investigation of the electric double layer, including how its structure depends on electrolyte speciation, electrode material and applied voltage. This talk will discuss instrumentation and image contrast mechanism, as well as highlight novel insights into the interfacial reaction microenvironment on aqueous battery electrodes and oxygen electrocatalysts.<br/><br/><br/>[1] Mefford, J.T. <i>et al.</i> <i>Nature.</i> <b>593</b>, 67–73 (2021).<br/>[2] Velasco-Velez, J-J. <i>et al</i>. <i>Science. </i><b>346</b>, 831-834 (2014).