In Aqua Electrochemistry Probed by XPEEM: Experimental Setup, Examples, and Challenges

Abstract

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.

The rise of electrochemical NAPXPS operated in the soft X-ray regime exemplified by the oxygen evolution reaction on IrOx electrocatalysts

“…Another approach for the investigation of solid-liquid interfaces with so Xrays is based on free standing 2D (graphene) membranes. [49][50][51] With this approach, the X-rays easily penetrate the graphene that, in turn, is also semitransparent to photoelectrons, i.e., the photoelectrons can escape the conned environment and be detected in the vacuum side where the hemispherical analyzer is placed. To enhance the mechanical stability of larger graphene layers, the graphene is transferred onto a holey SiN x membrane with an array of micro holes.…”

X‐Ray Microscopy of Halide Perovskites: Techniques, Applications, and Prospects

“…Recent advancements in PEEM acquisition have enabled time-resolved PEEM (TR-PEEM), and in-situ PEEM studies (temperature, pressure, and aqueous). [151][152][153][154] By applying time-resolved ultraviolet light excited PEEM (UV-PEEM), frame-by-frame imaging of the dynamics of carriers at localized traps at halide perovskite surfaces has been explored. [155] With temporal resolution on the picosecond timescale and ~100 meV energy resolution, Winchester et al identified nanoscopic, heterogeneously distributed hole traps at the surface of triple-cation perovskite (CsFAMAPbI 3 ) perovskite film, Figure 8d-f.…”

Operando X-ray characterization of interfacial charge transfer and structural rearrangements

“…26 A similar analysis was also performed for illumination and detection through a thin membrane. 129 For our electrocatalyst example from section 2.2, the situation is very different compared to the previous discussions in refs. 25,26 : not only the total signal of the interfacial layer but also the interface-sensitivity need to be considered.…”