Interface-Engineered Flexible Conductive Metal–Organic Framework Films for Multimodal Energy Applications

Conspectus Conductive metal–organic frameworks (c-MOFs) represent a distinct class of porous conductive materials. Compared with conventional MOFs, c-MOFs integrate intrinsically high electrical conductivity with a high surface area and an ordered porous structure, enabling efficient electron and ion transport. Engineering c-MOFs into continuous and flexible films offers a promising strategy for translating their properties into practical devices. Key strategies for film engineering include solution processing, interfacial growth, and chemical vapor deposition, which allow precise control over the film morphology, thickness, and alignment of conductive channels. Thin-film fabrication preserves structural integrity and pore connectivity, enhances interfacial contact, and facilitates device integration, thereby promoting coupled ionic and electronic transport. These properties render c-MOF films suitable for multimodal energy transformation. In energy storage, their mechanical compliance, flexibility, and high porosity enable conformal integration with deformable and wearable devices while maintaining rapid charge transport and long-term cycling stability. In energy harvesting and conversion, their ordered porous networks, tunable electronic structures, and freestanding mechanically flexible architectures enable efficient adaptation to diverse energy inputs, facilitating energy conversion involving electrical, mechanical, chemical, thermal, and optical processes while maintaining the structural integrity under dynamic deformation. This versatility supports the development of integrated systems capable of simultaneously storing, harvesting, and converting multiple energy modalities for wearable and portable devices. This Account highlights our recent studies on the nanoengineering of c-MOFs on the surface of cellulose nanofibers (CNFs) through interfacial synthesis, enabling the fabrication of freestanding, flexible, and mechanically robust CNF@c-MOF nanopapers, as well as their applications in energy harvesting, conversion, and storage. We discuss the fundamental principles governing the interfacial growth of c-MOF nanostructures on flexible nanofibrous substrates, including the regulation of metal–ligand coordination and interfacial chemical interactions that govern hierarchical assembly toward functional flexible architectures. This Account also summarizes recent advances in the fabrication of flexible c-MOF films, covering representative preparation strategies, structural design approaches, and their unique roles in emerging energy technologies. Future progress in metal center selection, ligand electronic modulation, pore architecture optimization, interface engineering, and composite integration will further improve electron–ion transport, mechanical durability, and device-level compatibility. By combining flexible substrates with multiscale hierarchical structures, flexible c-MOF films can establish interconnected transport networks and adaptive functional interfaces, enabling high-performance, lightweight, and multifunctional energy devices. These advances highlight flexible c-MOF films as a promising platform for next-generation energy technologies that simultaneously demand mechanical flexibility, structural stability, and efficient synergistic electron–ion transport.