Recycling Ti3C2Tx Oxide Nanosheets through Channel Engineering: Implications for High-Capacity Supercapacitors

Channel (hole and interlayer) engineering on two-dimensional (2D) MXenes has been proven to be an effective strategy to solve the issues of congested ion transport pathways, limited active sites, and sluggish ion transport kinetics caused by restacking of MXene nanosheets, which extended the application in the field of energy storage. Herein, a simple channel engineering strategy was proposed to treat the long-term stored Ti3C2Tx nanosheets, resulting in formation of an interlayer-expanded holey Ti3C2Tx film via etching out Ti3C2Tx oxides. The in situ oxides expanded the interlayer spacing and created holes on the Ti3C2Tx nanosheets, which formed channels in all directions. The interlayer-expanded holey Ti3C2Tx film showed outstanding electrochemical performance, with both high capacity (448 F g–1 at 2 mV s–1) and good cyclic stability (95.3% retention after 5000 cycles). Importantly, this strategy effectively recycles the waste MXenes that are oxidized by long-term storage, which embodies the concept of low carbon and environmental protection and promotes the industrialization process of MXenes.