Interfacial engineering of COFs-MXene hybrids: Advances and applications in high-performance supercapacitors

The growing demand for efficient energy storage systems with high energy output has driven significant interest in the development of supercapacitors with improved energy density and enhanced electrochemical performance. Two-dimensional transition metal carbides (MXenes) and covalent organic frameworks (COFs) have become the most promising electrode materials because of their distinct physicochemical characteristics. Despite their promising properties, covalent organic frameworks suffer from intrinsically low electrical conductivity and limited structural stability, while MXenes are constrained by challenges such as layer restacking, aggregation, and susceptibility to oxidative degradation. This review highlights advanced interfacial engineering strategies employed to integrate COFs with MXenes, enabling the formation of hybrid architectures that effectively mitigate the inherent limitations of individual components. Particular emphasis is placed on the fundamental charge storage mechanisms at COF-MXene interfaces, including electric double-layer capacitance and pseudocapacitive contributions. Furthermore, various synthesis methodologies-such as in situ growth, self-assembly, electrostatic interactions, and covalent bonding-are critically analyzed with respect to their influence on interfacial properties and overall electrochemical performance. The review presents the latest developments showing that rationally engineered COF-MXene hybrids have better specific capacitance (up to 390 Fg⁻¹), high-rate performance, and high cycling stability (more than 98% retention after 30,000 cycles). Moreover, we discuss the actual issues, such as scalability, stability in the long-run, and optimization of the interfaces, and suggest the perspectives of the research to be developed in the future in the direction of practical use in flexible, wearable and high-performance energy storage devices.