Synthesis And Characterization Of Titanium Nitride And Nickel Sulfide Nanomaterials

In this dissertation, new chemical methods were explored to synthesize of titanium nitride and nickel sulfide. Pyrolysis synthesis method and solution-based chemical method were all developed. TiN hollow nanocages were successfully synthesized Via Mg-thermal reduction, the possible growth mechanism was also studied at the same time. Nickel sulfide with different phases was synthesized by a simple mix-solvents sovothermal method. The morphologies of the as-prepared inorganic nanomaterials were characterized and the properties were investigated. The main contents are summarized as follows:1. Titanium nitride combines the characteristic properties of metal and ceramics, it is considered as promising refractory functional material, electronic material and catalytic material, so it attracts much attention in the basic study and the application In our experiment, TiN hollow nanocages have been successfully synthesized in large scale through a simple route by the reaction of TiO₂, N₂H₄·2HCl and Mg in a stainless-steel autoclave of about 20 ml capacity at 300-500℃. To the best of our knowledge, this is the first report about the synthesis of TiN hollow nanocages at such low temperature. When the experiment was carried out at relatively high/low temperature while keeping other conditions unchanged, the results indicated that relatively high temperature was favorable for the formation of TiN hollow nanocages while relatively low temperature tended to decrease the ratio of TiN hollow nanocages and only irregular TiN nanoparticals were obtained. TiN hollow nanocages mainly had diameters of 300 to 500 nm and shell thicknesses ranging from 20 to 35 nm, and the sample was well crystalline.Many TEM observations were carried out to further investigate the possible growth process and formation mechanism. When the sample was without any purification process, the sample was solid nanocage according to the TEM image. The inner content of the core-shell product was deduced to be MgO according to many experiments. Based on previous research and our experiment, a hard-template of MgO for the formation of TiN hollow nanocages was proposed. TiN hollow nanocages had a relative high thermal stability below 300℃in the air.In our experiment, Mg played an important role, decrease the Mg amount would appear TiN hollow nanocages, but also result in the appearance of impurities such as MgTiO₃, while increase Mg would appear TiN nanoparticles without any impurities. In absence of Mg or Na was used instead of Mg, no TiN was found. When NaN₃ was used instead of N₂H₄·2HCl, only TiN nanoparticles were found with few hollow nanocages2. It is well known that nickel sulfide has special photoelectric properties and they are widely applied as semiconductor materials. In our experiment, based on the complex solvothermal route, nanocrystalline NiS with different morphologies and different phases were synthesized by selecting NiCl₂·6H₂O as Ni-source and CH₅N₄S as S-source.Firstly, flower-like NiS (r-phase) was successfully prepared by a solvothermal synthetic route using ethylenediamine as solvent at 230℃. Based on the TEM observation results, it was found that the reaction time had influence on the morphology of the products. If the reaction time was prolonged the size of flower-like nickel sulfide became larger.Secondly, a capping agent-assisted solution-phase approach was developed to prepare rod-like NiS and NiS nanoparticles(r-phase).Thirdly, a solvothermal reduction method using the mixed solvents was developed to prepare h-NiS nanospheres and h-NiS nanoparticles. These nanospheres were generated by using glycol and water as mixed solvent at 180℃.