Research On Synthesis Of Low Dimensional Carbon Nano Structured Materials By Gas-liquid Detonation

The preparation of nanomaterials by detonation method is an integrated result of many different subjects which covering explosion mechanics,fluid mechanics,materials science,detonation physics,detonation chemistry and many other disciplines.It is one of the most dynamic topics in the field of explosion and also one of the most advanced topics in the world today.The instantaneous high temperature and high pressure generated by the detonation reaction can provide a favorable growth environment for the formation of nano materials,and the method for preparing nanomaterials has many advantages,like simple,efficient,green and low-cost.The gasliquid detonation method is an innovative technology in the detonation method.The high-energy igniter is used to detonate the gas-liquid mixed precursor to prepare nanomaterials and the products have higher purity and dispersibility compared with explosive detonation.In this paper,the carbon nano onion(CNOs),carbon nanotubes(CNTs)and carbon-coated titanium dioxide(Ti O2@C)were successfully synthesized by gas-liquid detonation for the first time,and the morphology,phase composition,elemental composition and thermal stability of the synthesized carbon nanostructured materials were analyzed with transmission electron microscopy and energy spectrometer(TEM-EDX),X-ray diffractometry(XRD),X-ray photoelectron spectroscopy(XPS),Raman spectroscopy(Raman),thermogravimetric analyzer(TG)and so on.The internal relations of gas-liquid detonation technology and the growth mechanism of carbon-based nanomaterials were discussed.The main research contents are as follows:1.The detonation pressure and detonation velocity during the detonation process were measured in real time using self-made of combustible gas driven multiphase precursor detonation device and detonation parameter test instrument.According to the experimental test results,the variation rules of key basic parameters during the detonation reaction were analyzed.Based on the detonation theory and the laws of thermodynamics,the theoretical calculations and experimental analysis are combined to study the variation of the characteristic parameters of the detonation environment.The results show that the actual measured detonation velocity and detonation pressure are slightly smaller than the theoretical solution,but the theoretical results can predict the actual results to a certain extent,which can provide a theoretical basis for the subsequent experimental study of efficient preparation of carbon nanostructured materials.2.Preparation of CNOs by gas-liquid detonation in a closed detonation tube with benzene,methane and oxygen as precursors.The effects of different gas concentrations on the preparation of carbon nano-onions were studied.With the increase of oxygen concentration in the precursor,the detonation velocity,pressure and temperature will increase correspondingly during the detonation reaction,the product particle size will decrease and the degree of graphitization will increase.When the detonation pressure is higher than 2.2MPa,detonation velocity exceeds 2000m/s and detonation temperature exceeds 4000 K,the carbon matrix is more easily graphitized and aggregated into the onion structure.3.Iron-based multi-walled CNTs were prepared by using ferrocene as metal catalyst and a mixture of methane,oxygen and camphor as precursor.When the carbon/iron atom is relatively low,the product mainly consists of CEMNPs,and as the carbon/iron atom ratio increases,carbon nanotubes are gradually formed.The detonation parameters of the formation environment of CEMNPs and CNTs are similar.The detonation pressure is about 1.7Mpa,detonation velocity is about 1700m/s,and detonation temperature is about 2800 K.4.Methane,oxygen,titanium tetrachloride and benzene were used as precursors for gas-liquid detonation and the effect of carbon concentration on the preparation of Ti O2@C was investigated.With the benzene content in the precursor increases,the diameter of the titanium dioxide gradually decreases,and the coated particles are also more and more.When the atomic ratio of carbon/titanium is about 26/1,the product coating effect is good.The particles are mainly spherical with diameter in 10-30 nm,and the core-shell structure is obvious.At this time,the detonation velocity is about 1700m/s,detonation pressure is about 1.7Mpa and detonation temperature is about 2500 K.Combined with Kruis model,it is found that both detonation temperature and carbon/titanium atomic ratio have an impact on the growth of titanium dioxide.When the temperature is lower and the carbon/titanium atomic ratio is higher,the particles diameter of titanium dioxide is smaller,which is easier to be coated.