<i>Operando</i> XAFS Reveals Dynamic Structural Evolution of Pt Single‐Atom Catalysts for Efficient Chlorine Electrosynthesis

Abstract Metal single‐atom catalysts (SACs) with near‐100% metal utilization and flexible coordination environments are promising candidates for electrochemical chlorine evolution reaction (CER) to produce valuable Cl 2 —a key raw material for plastics manufacturing, water treatment, and pharmaceuticals. However, it remains challenging to assess specific coordination environments for structure–activity relationships and monitor their dynamic structural evolution under catalytic reaction conditions. Herein, operando X‐ray absorption fine structure (XAFS) revealed distinct dynamic structural evolution on the low‐coordinated Pt site, compared to the conventional PtN 4 site. Specifically, the low‐coordinated Pt site transformed into an asymmetry PtN 2 Cl 2 structure upon exposure to a Cl − ‐containing solution, transiently evolved to PtN 2 Cl 4 intermediate at low overpotentials, and reverted to PtN 2 Cl 2 after CER. By overcoming the limitation of *Cl intermediate coverage on PtN 4 SAC, the low‐coordinated Pt SAC displayed superior CER performance to commercial RuO 2 and PtN 4 benchmarks. This work provides new insights into the rational design of coordination geometry in SACs for electrocatalysis.