Solvothermal Synthesis Of Cobalt And Nickel Selenides And Their Properties

Nickel and cobalt selenides are widely applied in the fields of catalyst, sensor materials, magnetic materials, cell and so on. It is important to explore novel synthesis and expand application extents of nickel and cobalt selenides. In this thesis, solvothermal routes have been chosen to synthesize Co0.85Se and NiSe nanosturctuers, and their applications in environmental protection have also been studied. The main contents are as follows:1. Nano nickel selenides with octahedral morphology were successfully synthesized via a simple mild solvothermal method. In the process, glycol was used as both solvent and reducing agent. The as-synthesized nano-sized nickel selenide was characterized by SEM, XRD, TEM, and so on. The results indicated that the formation of the octahedral NiSe was strongly dependent on the reaction temperature and reaction time. Interestingly, it was found that the as-prepared octahedral NiSe showed efficient catalytic performance for decomposition of hydrazine hydrate at room temperature.2. Hexagonal Co0.85Se with Ni0.85Se-type structure has been successfully synthesized without any surfactants by a solvothermal reduction route. X-ray diffraction (XRD), scanning electron microscopy (SEM), selected area electron diffraction pattern (SAED), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) method were used to characterize the structure, morphology and specific surface area of the Co0.85Se nanocrystals. SEM observation indicated that the obtained Co0.85Se nanocrystals were of Graphene-like morphology with thickness less than10nm. The as-prepared products have ferromagnetic at room temperature from magnetic measurement. And the products with high specific surface area could be used as adsorbent in wastewater treatment, which may be very useful for the environment.3. Uniform Graphene-like Co0.85Se nanosheets which exhibit a remarkable catalytic activity for the reduction of p-nitrophenol and a high adsorption capacity for Methyl Blue were prepared via a modified solvothermal process. The prepared nanosheets were applied to catalyze the reduction of p-nitrophenol in the presence of NaBHt, and the results indicated that the kinetic constant of the reaction increased when the concentrations of NaBH4and the amount of catalyst increased. The catalyst can be recycled a number of times after the quantitative reduction of4-nitrophenol. In addition, the adsorption efficiency for methyl blue was evaluated by the product and possible influence factors were discussed.