Site-selective and real-time observation of bimolecular electron transfer during photocatalytic water splitting

TL;DR

This study employs time-resolved X-ray absorption spectroscopy combined with ab initio calculations to observe bimolecular electron transfer in photocatalytic water splitting, providing insights for optimizing photocatalytic efficiency.

Contribution

First-time real-time observation of bimolecular electron transfer during photocatalytic water splitting using advanced X-ray spectroscopy and computational methods.

Findings

Identified specific molecular transitions involved in electron transfer.

Demonstrated the feasibility of time-resolved X-ray spectroscopy for studying photocatalysis.

Enhanced understanding of electron transfer mechanisms in water splitting.

Abstract

Time-resolved X-ray absorption spectroscopy has been utilized to monitor the bimolecular electron transfer in a photocatalytic water splitting system for the first time. 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$^{\rm III}$(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. The present findings enhance our understanding of functionally relevant bimolecular electron transfer reactions and thus will pave the road to rational optimization of photocatalytic performance.