Recent progress in the design of advanced MXene/metal oxides-hybrid materials for energy storage devices

The family of two-dimensional (2D) transition metal carbides, nitrides, and carbonitride, also called MXenes, have emerged as an attractive platform for constructing functional materials with enhanced properties for various energy applications. Transition metal oxides (TMOs) nanostructures supported on MXene nanosheets based on van der Waals interactions are facile, highly efficient, and low-cost, with self-assemble properties that can easily control their packing density. The resulting TMOs/MXene nanocomposites perfectly integrate the advantages of both components. MXene nanosheets can serve as conductive substrates to grow TMOs nanostructures which can facilitate fast electron and ion transport to prevent aggregation of TMOs nanostructures in energy applications. In turn, the TMOs nanostructures act as spacers to isolate the MXene nanosheets and prevent their re-stacking during assembly, enriching interfacial contacts and preserving the active sites. In this review, the recent advances of MXene/TMOs-based nanocomposites with enhanced performance for energy storage devices, such as supercapacitors (SCs), metal-ion hybrid capacitors (MIHCs), and various kinds of rechargeable batteries (RBs), are summarized and highlighted. We briefly discuss the synthesis methods, properties of MXenes, and the structural engineering of MXenes by introducing functionalized TMOs to achieve high-performance energy storage devices, such as in SCs, MIHCs, and RBs. Special attention is also given to MXene/TMOs nanocomposites-based SCs, HCs, metal-ion batteries, and metal-air/sulfur batteries. Finally, the crucial future outlook and perspective for developing MXene/TMOs nanocomposites for energy storage applications are also outlined.