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

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Abstract
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.
Funding Information
  • Natural Science Foundation of Shanghai Municipality (19ZR14668300, 21ZR1476200)
  • Youth Innovation Promotion Association of the Chinese Academy of Sciences (Y201842)
  • Key Laboratory of Receptor Research, Chinese Academy of Sciences (XDA 21000000)

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