Radiation‐Induced in Situ Construction of 2D Conductive Defect‐Rich Metal‐Organic Frameworks for High‐Performance Supercapacitor

2D conductive metal-organic frameworks (2D c-MOFs), featuring ordered 1D pore channels, extended 2D π-conjugated layered structures, and reversible redox-active sites, are identified as promising electrode materials for high-performance supercapacitors (SCs). Herein, a representative Cu-based 2D c-MOF (Cu-CAT) is synthesized for the first time through gamma ray radiation. The resulting Cu-CAT exhibited abundant defective structures and a higher proportion of low-valence Cu metal centers, attributed to in situ radiation-induced etching and reduction, while maintaining decent crystallinity and porosity. Interestingly, beneficial to the increased active sites resulting from the defects, the as-synthesized Cu-CAT electrode demonstrated remarkable capacitive performance in aqueous electrolytes (3.0 m KCl solution), achieving a specific capacitance of up to 508 F g^-1 at a current density of 0.2 A g^-1, surpassing that Cu-CAT synthesized via the conventional solvothermal processes (285 F g^-1 at 0.2 A g^-1) and most reported 2D c-MOFs. Furthermore, a symmetric two-electrode button cell fabricated using the as-synthesized Cu-CAT exhibited a high gravimetric capacitance of 365 F g^-1 at 0.5 A g^-1, a notable energy density of 50.72 W h kg^-1 at a power density of 0.25 kW kg^-1, and excellent cycling stability, retaining ≈91.6% of its initial capacitance after 10,000 cycles.