Synthesis And Properties Of Transition Metal Carbides Derivatives

In recent years,the two-dementional transition metal carbides?MXenes?,transition metal oxide/carbon composites and carbide derived carbon materials derived by transition metal carbides are widely used in lithium-ion batteries,super capacitors,water treatment and other fields and show excellent performance,which have aroused great concern of the researchers.However,the news report about the transition metal oxide/carbon composite materials in these transition metal carbide derivatives are relatively less,and the preparation process is more cumbersome.At the same times,the chlorine and other toxic gases used in the preparation of carbide derivatives will not only polluted the environment,but also threaten to human health.Therefore,to explore a more secure and simple synthesis of carbide derivatives path need to be solved.In this paper,we used Ti₃AlC₂ as the precursor to synthesis Ti02/C composites with different methods.Besides,we also explored a new and non-toxic etching agent CDC.All these materials are characterized by XRD,SEM and TEM and so on,and study the lithium storage performance as well.The accomplished results are as followings:?1?Synthesis two-dimensional Ti3C2 material by etching Ti₃AlC₂ with HF.Then to prepare TiO2/C composites through hydrothermal method.Controlling the addition amount of?NH4?2S2O4 and the hydrothermal temperature,we can get the optimum synthetic condition.Electrochemical test indicate that 201 mAh g-1 can be obtained of Ti02/C composites after 100 cycles at 0.2 C.?2?Selecting Na₂CO₃ as etching agent for the first time and Ti₃AlC₂ as precursor to make rutile Ti02/C composites by heating the mixture at high temperature.We got a series of TiO2/C composites with different morphology of TiO2 deposited on carbon layers when with different concentration of HC1 and bath temperature treated.When tested at 0.1 C,the capacity about 253mAh g-1 is obtained,and it can reach 38mAh g-1 at 50 C,which means a good rate capability.?3?Selecting Ti₃AlC₂ and Na₂CO₃ as the precursor and etching agent respectively to make CDC material by heating the mixture and dipping in HC1.The morphologies are different with different heating temperature.A high capacity of 598 mAh g-1 is obtained when tested at 0.1 C,and after 50 cycles at different current density the capacity is about 585 mAh g-1 when the current density come back to 0.1 C.Besides,the capacity maintained 93.4%after 100 cycles at 0.2 C,exhibiting good electrochemical properties.