Site‐Selective Real‐Time Observation of Bimolecular Electron Transfer in a Photocatalytic System Using L‐Edge X‐Ray Absorption Spectroscopy. Issue 7 (16th March 2021)

• Record Type: Journal Article
• Authors: Britz, Alexander; Bokarev, Sergey I.; Assefa, Tadesse A.; Bajnóczi, Èva G.; Németh, Zoltán; Vankó, György; Rockstroh, Nils; Junge, Henrik; Beller, Matthias; Doumy, Gilles; March, Anne Marie; Southworth, Stephen H.; Lochbrunner, Stefan; Kühn, Oliver; Bressler, Christian; Gawelda, Wojciech
• Is Part Of: Chemphyschem. Volume 22:Issue 7(2021)
• Page Start: 693
• Page End: 700
• Publication Date: 2021-03-16
• Subjects: homogeneous catalysis -- photocatalytic water splitting -- electron transfer -- x-ray absorption spectroscopy -- high energy-resolution -- fluorescence detection XAS -- ultrafast XAS -- restricted active space self-consistent field calculations; Chemistry, Physical and theoretical -- Periodicals; 541.05
• DOI: 10.1002/cphc.202000845
• Languages: English
• ISSNs: 1439-4235

Abstract

Abstract: Time‐resolved X‐ray absorption spectroscopy has been utilized to monitor the bimolecular electron transfer in a photocatalytic water splitting system. This has been possible by uniting the local probe and element specific character of X‐ray transitions with insights from high‐level ab initio calculations. The specific target has been a heteroleptic [Ir III (ppy)2 (bpy)] + photosensitizer, in combination with triethylamine as a sacrificial reductant and Fe 3 ( CO ) 12 as a water reduction catalyst. The relevant molecular transitions have been characterized via high‐resolution Ir L‐edge X‐ray absorption spectroscopy on the picosecond time scale and restricted active space self‐consistent field calculations. The presented methods and results will enhance our understanding of functionally relevant bimolecular electron transfer reactions and thus will pave the road to rational optimization of photocatalytic performance. Abstract : The light induced dynamics of an Iridium‐based photosensitizer for hydrogen generation were studied by picosecond‐resolved X‐ray absorption spectroscopy (XAS) during the primary steps of the photocatalytic cycle. We used total fluorescence yield and high‐resolution energy detection (HERFD) XAS spectra to follow the oxidation state of the central metal of an iridium‐based photosensitizer subject to photoinduced electron transfer. The detailed analysis of the main X‐ray transitions from the ground and excited states are guided by high‐level ab initio calculations.