Silane-Functionalized MXene-Templated Bimetallic Metal–Organic Framework Composites with Tailored Surface Chemistry for High-Performance Asymmetric Supercapacitors

This study functionalizes MXene surfaces using silane coupling agents to prepare organo-MXene (MX-C═C, MX-NH2, MX-NHC) with distinct functional groups (C═C, NH2, NHC), which are further in situ composited with bimetallic metal–organic frameworks (Ni, Co-MOF) to develop NiCo-MOF@organo-MX composite electrode materials. Structural characterizations confirm that the functionalization effectively alleviates MXene sheet stacking and regulates the morphology and distribution density of MOF particles. Electrochemical tests reveal that NiCo-MOF@MX-NHC exhibits optimal performance, achieving a specific capacitance of 1682.6 F g–1 at 1 A g–1 and retaining 68% capacity after 5000 cycles at 20 A g–1. The NH–CH3 functional group enhances pseudocapacitive behavior and charge transfer efficiency by modulating MXene surface active site density and MOF dispersion. Furthermore, an asymmetric supercapacitor assembled with tetraethylammonium tetrafluoroborate/acetonitrile (TEMA-BF4/AN) organic electrolyte demonstrates a wide voltage window of 2.4 V, delivering a high energy density of 41.5 Wh kg–1 at 24,000 W kg–1 power density, while successfully powering LED devices, validating its practical potential. This work provides theoretical and technical foundations for designing high-performance MOF@MXene composite electrodes.