Template Method And Application Of Low Dimensional Carbon Materials

Electromagnetic absorbing and shielding material play a vital important role in the field of electromagnetic protection,energy conversion and stealth technology.Different from traditional electromagnetic materials,the new electromagnetic materials are developing in the direction of low-dimensional,lightweight and multifunctional.The main purpose of this thesis is to prepare low-dimensional and lightweight carbon materials by template-assisted pyrolysis for electromagnetic absorbing and shielding to meet the modern demand for new electromagnetic materials.Furthermore,the electromagnetic performance of the material is regulated by changing the precursors and templates,as well as the reaction temperature.The materials were prepared with sodium chloride（Na Cl）as template with phthalocyanine and iron phthalocyanine as the carbon source.According the Atomic Force Microscope test results showed that few-layer graphene was successfully prepared.What’s more,the use of template method can successfully inhibit the phenomenon that small molecules phthalocyanine agglomerate to form bulk carbon materials.The influence of sintering temperature on product quality was studied,it was found that sintering temperature had a certain influence on the degree of graphitization of carbon materials.The general rule was that the degree of graphitization of carbon materials would increase with the increase of temperature.By changing the precursor to add iron,it was found that iron has an effect on the relative content of pyridine nitrogen and graphitic nitrogen,and the addition of iron will increase the relative content of pyridine nitrogen.The defect brought by pyridine nitrogen can become a polarization center,which can improve the absorbing performance.The samples obtained by sintering phthalocyanines with Na Cl as the template can achieve an effective absorption bandwidth of 6.7 GHz with a filling loading of 4 wt.% and a coating thickness of 2.5 mm.However,when the carbon source was changed and iron phthalocyanine was used as the carbon source,the effective absorption bandwidth was 6.4 GHz when the coating thickness was2.3 mm,and the loss value at this time was as high as-35.7 d B,and the prepared lowdimensional carbon material has a shielding efficiency of 30 d B.Thesis found that due to the different surface adsorption energies of small molecules phthalocyanine to sodium chloride and potassium chloride,when potassium chloride was used as a template,the surface adsorption energy of potassium chloride and small molecules phthalocyanine was small,so an extremely thin transparent graphene film is formed.And the specific surface area of the samples obtained after sintering with potassium chloride as a template has a substantial increase.Potassium chloride as template iron phthalocyanine as carbon source,the samples obtained by sintering at 700 ℃due to the introduction of iron elements and the increase of the interface polarization absorption performance was great.The filling degree is only 1 wt.% and the coating thickness of 3.1 mm is thinner,but the effective absorption bandwidth of 7.8 GHz can be achieved at the layer thickness,and the absorption in the X-band is a full-screen segment when the coating thickness is 3.9 mm.Based on this work,a new type of carbon-based light absorbing material with excellent performance was prepared by a simple and green template method,which improved the absorbing performance while reducing the filling degree of the material,which is the application of new low-dimensional carbon-based absorbing materials.The research provides a new way of thinking.