Single‐Atom Photocatalysts on TiO ₂ : Insights from X‐Ray Absorption Spectroscopy

Surface modification of TiO 2 with single‐atom catalysts (SACs) is an effective strategy for enhancing photocatalytic efficiency. However, thorough characterization of SACs at the atomic scale remains challenging. X‐ray absorption spectroscopy (XAS) offers unique advantages for the in‐depth analysis of TiO 2 ‐supported SACs. By employing XAS, the local atomic structure, oxidation state, and electronic properties of the SACs, as well as the underlying photocatalytic mechanism, can be revealed. Herein, we present a short review on the application of XAS in studying TiO 2 ‐supported SACs. We first elucidate the key role of XAS in simultaneously probing the structure and electronic properties of monometallic SACs across different periods. Next, we discuss XAS studies of bimetallic SACs from the perspective of each constituent element and highlight the element‐specific capabilities of XAS for analyzing multi‐element SACs. Finally, we demonstrate how in situ XAS can effectively monitor structural and electronic property changes in SACs under real photocatalytic reaction conditions. Overall, this review highlights the unique advantages of XAS in achieving a more comprehensive understanding of the structure−property relationships in SACs, ultimately aiding the rational design of future photocatalysts. Additionally, we provide practical suggestions for utilizing XAS more efficiently in the analysis of various SAC systems.