One-Pot Green Process to Synthesize MXene with Controllable Surface Terminations using Molten Salts

Surface terminations of two-dimensional MXene (Ti3C2Tx) considerably impact its physicochemical properties. Commonly used etching methods usually introduce -F surface terminations or metallic impurities in MXene. We present a new molten-salt-assisted electrochemical etching method to synthesize fluorine-free Ti3C2Cl2. Using electrons as reaction agents, cathode reduction and anode etching can be spatially isolated; thus, no metallics are present in the Ti3C2Cl2 product. The surface terminations can be in situ modified from -Cl to -O and/or -S, which considerably shortens the modification steps and enriches the variety of surface terminations. The obtained -O-terminated Ti3C2Tx are excellent electrode materials for supercapacitors, exhibiting capacitances of 225 F g(-1) at 1.0 Ag-1, good rate performance (91.1 % at 10 Ag-1), and excellent capacitance retention (100 % after 10000 charge/discharge cycles at 10 Ag-1), which is superior to multi-layered Ti3C2Tx prepared by other etching methods.

Automated summary

A new molten-salt-assisted electrochemical etching method was developed to synthesize fluorine-free Ti3C2Cl2, allowing for the modification of surface terminations and enhancement of electrode material performance.