Room-temperature prepared MXene foam via chemical foaming methods for high-capacity supercapacitors

Constructing 3D porous MXene from 2D nanosheets is the most efficient method to avoid restacking of nanosheets and enhance the application of nanomaterials at macroscale. Direct foaming from solids is an ideal means to obtain 3D porous structure. However, MXene is difficult to be physically foamed because its plasticity is not enough. Herein, we invent a chemical foaming method to convert MXene films into foams with good porosity. The wet film of Ti ₃C ₂T _x precursor with interlayer water has super high plasticity, which is more conducive to the introduction of foaming agent and the foaming process. The obtained Ti ₃C ₂T _x foams exhibits good porosity and higher specific surface area than Ti ₃C ₂T _x films, resulting in outstanding capacitive performance (426 F g ⁻¹ at 1 A g ⁻¹) with good rate performance (190 F g ⁻¹ at 10 A g ⁻¹ ) and excellent cycle stability (92% retention after 10,000 cycles). The supercapacitor fabricated with Ti ₃C ₂T _x foams display an outstanding energy density of 14.1 Wh kg ⁻¹ at a power density of 250 W kg ⁻¹. Moreover, the foaming method creates a up-bottom construction patterns, which is simple, low cost and easy for scalable fabricating porous MXene.