ABSTRACT The electrocatalytic chlorine evolution reaction (CER) is central to chlor‐alkali industries and water treatment, yet its practical deployment is still constrained by high energy demands and insufficient selectivity. Here, we report a “mortise‐and‐tenon” strategy using a tulip‐shaped covalent organic framework (Tu‐COF) precursor to construct heteronuclear Ru‐Ln dual‐atom catalysts (Ln = La, Ce, Pr). The pre‐organized micropores of Tu‐COF serve as atomic‐scale nanoreactors, enabling precise confinement and pairing of Ru and lanthanide atoms. Among them, Ru‐Ce delivers outstanding CER performance, achieving 150 mA cm −2 at 1.45 V versus RHE with nearly 100% Faradaic efficiency for Cl 2 evolution and over 500 h stability in a flow cell. Mechanistic studies identify the in situ formed RuCeCl‐N 6 motif as the active site. Density functional theory calculations reveal that adjacent Ce modulates the Ru center's d‐band structure and charge distribution, enhancing initial Cl adsorption on RuCe‐N 6 while optimizing subsequent Cl adsorption on RuCeCl‐N 6 . This lowers the free‐energy barrier for Cl–Cl coupling and suppresses competing OOH * formation, thereby accelerating CER kinetics and intrinsically improving activity and selectivity. This work offers a generalizable strategy for heteronuclear DAC construction and highlights lanthanide‐mediated electronic engineering as a powerful approach to electrocatalyst design.
Zhang et al. (Tue,) studied this question.