Preparation,Adsorption And Electrochemical Performance Of Two-dimensional Carbide Crystals Of MXene

MXene,a family of early transition metal carbides and carbonitrides,with like-graphene structure,is a novel 2D materials,which are synthesized by removing A-site elements from M_n+1AX_n phases.Where n=1,2,or 3,M is an early transition metal,A represents an A-group element,and X is carbon and/or nitrogen.In this paper,we research the preparation of Ti₂C and V₂C by successfully selective etching Ti₂AlC and V₂AlC with fluoride salts.The structures of MXene were determined with X-ray diffraction?XRD?and Raman spectroscopy analysis.The morphologies and pore size distribution of MXenes were analyzed by scanning electron microscope?SEM?,transmission electron microscope?TEM?,Nitrogen sorption technique and gas adsorption analyzer.Gas adsorption and electrochemical performance of Ti₂C and V₂C were measured,respectively.Two-dimentional crystals Ti₂C was synthesized by using the same mass fraction and the same molar concentration of fluoride salt solution,respectively.The results of XRD shown that etching temperature and time are the main factors.Ti₂C was further exfoliated by intercalation with dimethylsulfoxide?DMSO?,NH₃·H₂O and urea.The results of nitrogen adsorption showed most pores in Ti₂C mesopores,and the corresponging specific surface area?SSA?of Ti₂C was calculated to be 19.1 m²/g.Methane adsorption analysis showed the methane adsorbed amount at 25oC and 50oC under 5 MPa are 11.58 cm³?STP?/g and 52.76 cm³?STP?/g,respectively.It can be found that the adsorption quantity increases with the temperature rises.Furthermore,after the intercalation,the adsorbed amount of methane at 25oC under 5 MPa is 16.81cm³?STP?/g.The results of CO₂ adsorption indicated CO₂ adsorption capacity increased with the temperature rises.High pure V₂C MXene,a novel two-dimensional carbide,was successfully synthesized by etching V₂AlC with sodium fluoride and hydrochloric acid at 90°C for72 h.And the SSA of V₂C was 9.58 m²/g.Electrochemical measurements showed MXene V₂C has a large lithiation and delithhiation potential as anode for lithium ion batteries.It exhibited a stable capacity of 291 mAh/g at 1C?1C=370 mA/g?rate.The result suggested that V₂C has an excellent structure stability and cycling stability,and V₂C is a promising anode material with excellent performance.