Solvothermal Synthesis And Electrochemical Properties Of Nickel Selenide Compounds

Facing the gradual depletion of fossil fuels and imminent situation of new energy research, nickel selenide compounds gain increasing attention and will be developed into some significant and widely used applications because of its excellent properties in electricity, magnetism, optics and so on. Currently, there are many methods to synthesize nickel selenide compounds, in which solvothermal method has received special attention for easy controlment and growth. In this paper, the experiment used diethylene glycol as solvent to synthesize different morphologies of nickel selenide compounds by one-step solvothermal method, and the morphology of the products were characterized and the electrochemical properties of the product were tested. The main contents of this paper are listed as follows: 1 NiSe2 with different morphologies were successfully synthesized by solvothermal method with diethylene glycol（DEG） as solvent, NiCl2·6H2O as Ni source and SeO2 as Se source. The structure and morphology of the product were characterized by scanning electron microscope（SEM）, X-ray diffraction（XRD）, energy dispersive spectroscopy（EDS）, Raman spectroscopy. The electrochemical properties of NiSe2 were analyzed by electrochemical workstation. In this thesis, the effect of n（Ni）: n（Se）, reaction time, temperature, surfactant to the shape of NiSe2 were investigated. We analyzed the effects of different factors on the products’ morphologies. We found a suitable reaction conditions for preparing the morphology of octahedron, polyhedron, dendritic, and quasi-spherical.2 Ni_0.85 Se with different morphologies were successfully synthesized using diethylene glycol（DEG） as solvent, NiCl₂·6H₂O as Ni source and SeO₂ as Se source. In this process, NaOH and hexadecyltrimethylammonium bromide（CTAB） were used as additive. The morphology of the samples was characterized by SEM and XRD. Comparing with the influence of different amounts of NaOH or CTAB on the morphology of the samples, we find that NaOH has a significant influence on the morphology of the product, and excessive CTAB can make the shape of the sample more regular and the dispersion of the sample better.3 NiSe with different morphologies were synthesized by polyol method in the presence of PVP and NaOH as additive. In this process, DEG was used as a solvent with NiCl₂·6H₂O as Ni source and SeO₂ as Se source. The morphology of the samples was characterized by SEM and XRD. We studied the effect of PVP, NaOH and reaction time on the morphology of the product. Experimental results show that PVP and reaction time have a significant influence on the morphology of the product, and the effect of NaOH on the morphology of the product is small.4 Based on the analysis of the experimental phenomena and results, this master’s thesis expounds the growth mechanism of NiSe₂ and Ni1-xSe（x=0⁰.15） compounds. The suitable reaction conditions of samples with different morphologies are summarized.