Constructing titanium carbide MXene/reduced graphene oxide superlattice heterostructure via electrostatic self-assembly for high-performance capacitive deionization.

Capacitive deionization has attracted wide concern on accountof its high energy efficiency, low manufacturing cost and environmental friendliness. Nevertheless, the development of capacitive deionization is still impeded because of the scarcity of suitable electrode materials with superior performance. Herein, we successfully prepared the two-dimensional (2D) titanium carbide (TiCT) MXene/ reduced graphene oxide (rGO) superlattice heterostructure by a facile electrostatic self-assembly strategy and systematically investigated its performance as capacitive deionized electrode materials. The unique 2D/2D superlattice heterostructure not only effectively alleviates the self-stacking problem of TiCT MXene nanosheets, but also endows the heterostructure with superior conductivity and fast ion diffusion rate. As a result, the MXene/rGO superlattice heterostructure exhibits an outstanding salt (Na) adsorption capacity (48 mg g) at 1.2 V significantly superior to pristine TiCT MXene nanosheets, along with outstanding long-term cycling performance. Furthermore, the mechanism involved was elucidated through comprehensive characterizations. Therefore, this study offers a new pathway for designing high-performance electrode materials for capacitive deionization.