Atomic Pt‐N₄ Sites in Porous N‐Doped Nanocarbons for Enhanced On‐Site Chlorination Coupled with H₂ Evolution in Acidic Water

Abstract Acidic water electrolysis (AWE) has the potential to revolutionize green H₂ generation with flexible partial load range, high gas purity, and rapid system response. However, the extensive usage of noble Ru/Ir metals and sluggish oxygen evolution reaction (OER) with inexpensive O₂ products pose significant challenges in anodes. Herein, it is demonstrated that ultralow Pt single atoms in highly porous N‐doped carbons (Pt₁/p‐NC@CNTs) can effectively catalyze chlorine evolution reaction (CER) for on‐site chlorination to replace OER in AWE, with 200 mV potential saving at 10 mA cm⁻². As a result, various organic halide motifs of pharmaceutical molecules by chlorinating anisole, ketones, and olefins can be realized, along with H₂ coproduction. Combined physicochemical characterizations including synchrotron X‐ray absorption spectroscopy, finite element methodsimulations, and theory calculations indicate that atomic Pt‐N₄ active sites balance the adsorption/desorption of Cl intermediates (Volmer step) and the plentiful porosity of Pt₁/p‐NC@CNTs with high specific surface area of 313 m² g⁻¹ enriches Cl⁻ around active sites (Heyrovský step), collectively promoting the rate‐limiting Volmer–Heyrovský pathway for improved CER.