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Jaeker_Insitucell_11042020_final2.pdf (4.65 MB)
Flow Cell for Operando X-Ray Photon-in-Photon-out Studies on Photo-Electrochemical Thin Film Devices
Preprints are manuscripts made publicly available before they have been submitted for formal peer review and publication. They might contain new research findings or data. Preprints can be a draft or final version of an author's research but must not have been accepted for publication at the time of submission.
submitted on 28.05.2020 and posted on 29.05.2020by Philipp Jäker, Dino Aegerter, Till Kyburz, Roman Staedler, Rea Fonjallaz, Blanka Detlefs, Dorota Koziej
Photo-electro-chemical (PEC) water splitting represents a promising technology towards an artificial photosynthetic device but many fundamental electronic processes, which govern long-term stability and energetics are not well understood. X-ray absorption spectroscopy (XAS), particularly its high energy resolution fluorescence-detected (HERFD) mode, emerges as a powerful tool to study photo-excited charge carrier behavior under operating conditions. The established thin film device architecture of PEC cells provides a well-defined measurement geometry, but it puts many constraints on conducting operando XAS experiments. So far, operando cells have not been developed that enable to concurrently measure highly intense X-ray fluorescence and photo-electro-chemical current without experimental artifacts caused by O2 and H2 bubbles formation. Moreover, we are missing a standardized thin film exchange procedure. Here, we address and overcome the instrumental limitations for operando HERFD-XAS to investigate photo- and electrochemical thin film devices. Our cell establishes a measurement routine that will provide experimental access to a broader scientific community, particularly due to the ease of sample exchange. Our operando photo-electro-chemical cell is optimized for the HERFD-XAS geometry and we demonstrate its operation by collecting high-resolution Fe K-edge spectra of hematite (α-Fe2O3) and ferrite thin film (MFe2O4, M= Zn, Ni) photoelectrodes during water oxidation.