Highly Selective and Stable Covalent Organic Framework Electrocatalysts for Sustainable Chlorine Evolution

The electrochemical chlorine evolution reaction (CER) is crucial for the chlor-alkali industry but is often hindered by the competing oxygen evolution reaction (OER). The current electrocatalysts for CER have been predominantly metal-based or noble-metal-based materials, such as dimensionally stable anodes (DSAs). Herein, we synthesized a series of metal-free covalent organic frameworks (Tp-Pa-COFs), showing an unexpected CER activity with an overpotential (102 mV) lower than DSA (182 mV) at a current density of 400 mA cm^-² at 90 °C. The Tp-Pa-COF showed superior CER selectivity (100 ± 4%) and stability (over 200 h) compared to noble metal and non-noble metal catalysts. Through operando characterization and theoretical calculations, we identified carbonyl and amine groups as active sites, where preferential Cl^- adsorption breaks the conventional CER-OER scaling relationship. This study highlights the potential of COF-based materials as highly efficient, sustainable alternatives for industrial chlorine production, advancing the development of metal-free electrocatalysts.