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The increasing demand for new catalysts for the generation and storage of clean energy requires sophisticated techniques to better understand the reaction mechanisms and ultimately improve the performance of these systems. Although ex-situ characterization is already very useful, the behavior of the catalyst may differ significantly when placed under real operating conditions such as, for example, the presence of the electrolyte and applied potential. Therefore, in-situ techniques are desirable, since they allow us to not only follow in real time and conditions the modifications in the catalyst structure, but also to unravel the linked reaction mechanism. In this work, in-situ X-ray absorption spectroscopy (XAS) is used to monitor the structural changes in the catalyst, such as oxidation state, coordination number, composition, and bond distance in dependence on electrode potential.
However, one of the major challenges in the XAS-Electrochemistry coupling is the disturbance of the transmittance measurement by the presence of gas bubbles (e.g. oxygen evolution reaction) in the detection region. This problem is usually solved by using the fluorescence mode, but for samples that show strong self-absorbance (highly concentrated or very rough samples), this is not a possibility. Quick-EXAFS (QEXAFS) is used to obtain time-resolved measurements during the very fast measurements but can also be applied to reduce the interferences from bubbles, since many spectra are acquired in a few seconds, which allows the measurements that show distorted signals due to the gas evolution to be excluded. In this talk, results obtained at P64 for NiFe layered double hydroxides catalysts applied for water electrolysis will be presented.