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

Acidic water electrolysis (AWE) has the potential to revolutionize green H 2 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 O 2 products pose significant challenges in anodes. Herein, it is demonstrated that ultralow Pt single atoms in highly porous N‐doped carbons (Pt 1 /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 H 2 coproduction. Combined physicochemical characterizations including synchrotron X‐ray absorption spectroscopy, finite element methodsimulations, and theory calculations indicate that atomic Pt‐N 4 active sites balance the adsorption/desorption of Cl intermediates (Volmer step) and the plentiful porosity of Pt 1 /p‐NC@CNTs with high specific surface area of 313 m 2 g −1 enriches Cl − around active sites (Heyrovský step), collectively promoting the rate‐limiting Volmer–Heyrovský pathway for improved CER.