Linker-Engineered Interfaces in MXene/COF Heterostructures: Synthesis to Structure-Property-Performance Relationships in Electrochemical Energy Storage.
Electrochemical energy storage systems demand electrode materials that simultaneously combine high electrical conductivity, large ion-accessible surface area, chemical stability, and mechanical integrity, requirements that are rarely satisfied by single-component materials. Rationally engineered heterostructures have therefore emerged as an effective strategy to integrate complementary functionalities. Among them, MXenes, a class of two-dimensional (2D) transition-metal carbides and nitrides, provide metallic conductivity, hydrophilic surfaces, and abundant functional terminations, while covalent organic frameworks (COFs) offer ordered porosity, tunable chemistry, and intrinsic redox activity. The integration of these materials into MXene/COF heterostructures has demonstrated significant performance improvements; however, achieving true synergy critically depends on the nature of the interface. Here, we establish a linker-centric framework, highlighting that the MXene/COF interface acts as an active regulator of charge-transfer kinetics, ion transport, and structural stability rather than a passive boundary. We systematically classify interfacial interactions into covalent linkers (imine, azine, β-ketoenamine, amide, and hydrazone) and non-covalent interactions (hydrogen bonding, electrostatic coupling, and π-π stacking), and evaluate how their bonding characteristics govern the trade-offs among electronic coupling, ion accessibility, and durability. Finally, synthesis strategies, characterization approaches, representative applications, and future directions are discussed to guide the rational design of next-generation MXene/COF energy storage systems.