Topological Transformation of MXenes to Non-Van Der Waals Artificial Solids with Well-Defined Structure.

Two-dimensional (2D) transition metal carbides, nitrides, or carbonitrides (MXenes) have become an ideal platform to produce some derivatives with tunable chemical compositions and structures, possessing unique physical and chemical properties beyond their counterparts. Here, a well-defined non-van der Waals artificial solid is developed on the basis of the topological transformation of Cl-terminated MXenes, which involves the substitution of -Cl with -S terminations to enlarge the interlayer spacing of MXenes and subsequent configuration with transition-metal (Cu, Fe, Co, Ni, and Sn) atoms. After the topological transformation, the MXene layers are chemically bonded, showing a higher thermal stability up to 550 °C in air than that of MXenes. The resultant artificial solids with well-defined atomic metal layers exhibit a high electrocatalytic activity to I2/I- redox reaction and a strong adsorption capability toward iodine species. As a result, Zn-I2 batteries deliver a good rate performance of 104 mAh g-1 at 32 C and a long cycling stability of up to 2000 cycles at 8 C.