Measurement cell for in situ elemental mapping of (photo-)catalytically active substances in wet soft matter samples by micro X-ray fluorescence spectroscopy

To meet the demand for analyzing the spatial distribution of elements in native soft matter materials for (light-driven) catalysis using two-dimensional micro X-ray fluorescence, a measurement cell and clamping tool setup was developed. The cell features a large measurement area, isolates the sample to prevent evaporation, provides structural support and can be easily assembled. For the first time, this setup enables the measurement of moist samples of functionalized soft matter materials without additional preparation over prolonged periods without falsification of the measurements due to changes during the measurement. This development enables semi-quantitative comparisons of the elemental composition and distribution of different samples, as well as within the same sample, over time. The applicability and reproducibility of the measurement cell is demonstrated for so-called POMbranes, nanoporous block copolymer membranes functionalized with the polyoxometalate cluster [Co4(H2O)2(PW9O34)2]10-, which could be measured under wet conditions. For these samples, the improved homogeneity of the elemental distribution with increased loading time was proven quantitatively. The improved measurement conditions enable identification of small variations that occurred accidentally during the experiments.