Aqueous Cascade Synthesis of Robust Dual‐Linkage Covalent Organic Frameworks for Efficient Hydrogen and Oxygen Evolution at an Industrial‐Level Current Density

ABSTRACT One‐step integration of robust dual linkages into a covalent organic framework (COF) in H 2 O remains a significant challenge. Herein, we report an aqueous‐phase synthesis strategy for constructing crystalline COFs containing both propenone and meta ‐pyridyl linkages via a one‐pot cascade reaction. This approach ingeniously combines reversible aldol condensation with irreversible Chichibabin pyridine synthesis, leveraging the intermediate role of chalcone units to promote error corrections for crystallization. The resulting dual‐linkage COFs (termed PYP‐1, ‐2, ‐3) exhibit well‐defined crystalline structures. When evaluated as metal‐free electrocatalysts, PYP‐3 delivers superior performance, achieving a low overpotential of 46 mV for the hydrogen evolution reaction (HER) at 10 mA cm −2 and outstanding durability for the oxygen evolution reaction (OER) exceeding 600 h at an industrial current density of 500 mA cm −2 . In situ FTIR spectra and density functional theory calculations reveal that the high‐density pyridinic nitrogen sites function as intramolecular proton relays, facilitating concerted proton‐coupled electron transfer and optimizing intermediate adsorption via donor‐acceptor interactions. This work establishes a green and versatile platform for constructing dual‐linkage COFs and highlights their potential as advanced electrocatalysts for sustainable energy conversion.