In aqua electrochemistry probed by XPEEM: experimental setup, examples, and challenges.

Recent developments in environmental and liquid cells equipped with electron transparent graphene windows have enabled traditional surface science spectromicroscopy tools, such as X-ray photoelectron spectroscopy (XPS), photoemission electron microscopy (PEEM), and scanning electron microscopy (SEM) to be applied to study solid-liquid and liquid-gas interfaces. Here, we focus on the experimental implementation of PEEM to probe electrified graphene-liquid interfaces using electrolyte-filled microchannel arrays as a new sample platform. We demonstrate the important methodological advantage of these multi-sample arrays: they enable the combination of the wide field of view hyperspectral imaging capabilities from PEEM with the use of powerful data mining algorithms to reveal spectroscopic and temporal behaviors at the level of the individual microsample or the entire array ensemble