Approaches to achieve surface sensitivity in the in situ XAS of electrocatalysts

In situ and operando techniques providing information regarding adsorbate bonding and atomic arrangements on the electrode surface along with pure electrochemical measurements are needed to more fully understand the detailed mechanism of electrocatalytic reactions on high surface areas/nanoparticle electrocatalysts. X-ray adsorption spectroscopy (XAS) is a powerful tool to interrogate the electronic structure and local coordination environment of such electrocatalysts under working conditions, but it should be acknowledged that standard XAS methods are not intrinsically surface sensitive. This review will present recent in situ XAS studies on single-atom, metal, and metal oxide electrocatalysts, highlighting the approaches taken to achieve surface sensitivity by careful designing of the sample under investigation.