Solar energy conversion such as solar fuel catalysis requires multiple coordinated reaction steps in a series of electron and proton transfers across multiple timescales. In order to resolve detail mechanisms underlying solar energy conversion, the electronic and structural changes must be followed in-situ, across the full time domain of the reaction coordinate. We have implemented X-ray Multi-Probe (XMP) Transient X-ray Absorption Spectroscopy (MXTA) capability that can acquire a large number of time-resolved X-ray absorption spectra simultaneously over a wide time window from tens of picoseconds to hundreds of microseconds. This capability is extremely useful in studying complex solar energy conversion processes with multiple reaction channels and mixtures of intermediate species. Two examples that applying MXTA will be presented. The first is tracking how charge flows in a lead-free photovoltaic perovskite material: Cs3Bi2Br9. The photo-induced polaron formation as well as asynchronous structural and electronic dynamics have been observed. The second study is on a molecular-based photocatalytic hydrogen generation reaction using an organic photosensitizer and an iron-porphyrin based catalyst. The detailed electron transfer dynamics as well as the complete photoreaction pathways have been revealed with unprecedented detail.

Resolving multiple-step photochemical reaction mechanisms underlying solar energy conversion

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.