In Situ Synthesis of MXene with Tunable Morphology by Electrochemical Etching of MAX Phase Prepared in Molten Salt

摘要

MXenes, a rapidly growing family of 2D transition metal carbides, carbonitrides,and nitrides, are one of the most promising high-rate electrode materialsfor energy storage. Despite the significant progress achieved, the MXenesynthesis process is still burdensome, involving several procedures includingpreparation of MAX, etching of MAX to MXene, and delamination. Here, aone-pot molten salt electrochemical etching (E) method is proposed to achieveTi_2C MXene directly from elemental substances (Ti, Al, and C), which greatlysimplifies the preparation process. In this work, different carbon sources, suchas carbon nanotubes (CNT) and reduced graphene oxide (rGO), are reactedwith Ti and Al micro-powders to prepare Ti_2AlC MAX with 1D and 2D tunedmorphology followed by in situ electrochemical etching from Ti_2AlC MAX toTi_2CT_x MXene in low-cost LiCl-KCl. The introduction of the O surface groupvia further ammonium persulfate (APS) treatment can act in concert with Cltermination to activate the pseudocapacitive redox reaction of Ti_2CCl_yO_z in thenon-aqueous electrolyte, resulting in a Li+ storage capacity of up to 857 C g~(?1)(240 mAh g~(?1)) with a high rate (86 mAh g~(?1) at 120 C) capability, which makesit promising for use as an anode material for fast-charging batteries or hybriddevices in a non-aqueous energy storage application.