Time-Resolved X‑ray Absorption Spectroscopy and Diffraction toward Solar Energy Conversion

Time-resolved X-ray absorption spectroscopy (TR-XAS) and diffraction (TR-XRD), employing a laser pump-X-ray probe scheme, have emerged as pivotal tools for unraveling the intricate electronic and structural dynamics of light-driven excited and intermediate states in materials that are crucial for solar energy conversion. At the Advanced Photon Source (APS), these approaches enable investigations spanning time scales from picoseconds (ps) to microseconds (μs), providing element-specific and atomic-level insights into transient states to inform the rational design of next-generation materials with enhanced solar energy conversion efficiencies. This review highlights the recent technical advancements in TR-XAS and TR-XRD at APS, with an emphasis on applications for solar energy conversion. By integrating X-ray and laser pulses using different timing-pattern schemes, we develop several innovative TR-XAS and XRD methodologies. Representative scientific studies are presented to illustrate their use in characterizing molecular photocatalysts, metal halide perovskites, and traditional semiconductor materials in diverse forms, including solutions, suspensions, and solids.