Operando EXAFS and XANES of Catalytic Solids and Related Materials

The continuous improvement of X-ray sources, optics, and detectors since the start of the twenty first century has paved the way for unprecedented studies of functional materials at work. Studying these typically highly complex materials while they are working requires a sophisticated combination of analysis techniques that can provide chemical information about the ongoing processes at multiple time- and/or length scales. This makes X-rays an excellent probe for such studies, as they are (usually) non-destructive, can be used for relatively fast processes (0.01–2 s), and can operate in harsh environments, for example under high pressure or temperature. In order to link the (spatio-)temporal chemical information obtained by X-ray absorption spectroscopy (XAS) to the task performed by the functional material, it is necessary to collect additional complementary information about the running process (performance). It is this simultaneous measurement together with a combined data analysis that defines “operando” studies.