Preparation And Properties Of Nanomaterials Of Germanium Compounds

In recent years, due to their wide applications in semiconductors, photoelectronics, photocatalysis, and lithium ion batteries, synthesis and properties research of germanium contained compounds nanomaterials has attracted much attention and being a hot research field.Based on the above, a series of germanium contained compounds nanomaterials with high purity and crystallinity as well as GeS2-rGO nanostructures were prepared using a low temperature solvothermal technique. Systematic characterizations were carried out on the products by using XRD, HRTEM, XPS, EDX, FT-IR, Raman, and UV-vis-NIR. In the meanwhile, influences of temperatures, capping agents, pH, reaction time, and concentrations on compositions, morphologies, and crystallinity of the products were discussed. Furthur more, photocatalytic activity, electrochemical and photoelectrochemical behaviors of the as-prepared products were tested. After systematic study, some interesting results were obtained in this thesis:Firstly, crystalline GeS2 nanoplates were obtained successfully through a low-temperature (140℃) solvothermal process by using GeCl4 and thioacetamide as germanium and sulphur source respectively. Hydrogen evolution from photocatalytic water splitting over the as-prepared GeS2 nanoplates was explored using Na2S and K2SO3 as sacrificial reagents. The results indicated that the as-prepared GeS2 nanoplates can serve as a potential photocatalyst. During 13 hours’irradiation, a mean rate of 144 μmol·g-1·h-1 of H2 evolution was oberserved. What’s more, the synthesis method we have established may contribute to further studies of single layer or few layer germanium disulphide nanosheets.Secondly, GeS2-rGO nanocomposites were prepared in a one-pot solvothermal process. Electrochemical and photoelectric behaviors of the as-prepared GeS2-rGO nanocomposites were studied. Several conclusions can be obtained from the studies:the addition of rGO can significantly enhance the optoelectric property of GeS2. When rGO content is 4.8%, the photocurrent density of rGO-GeS2 nanocomposites is 11 times higher than bare GeS2. Besides, GeS2-rGO nanocomposites is a promising electrode material for lithium ion batteries. When the nanocomposites (9% rGO) were used as electrode material in a lithium ion battery, the discharge capacity of first cycle can be as high as 2469.3 mA h·g-1. Thus, the rGO-GeS2 nanocomposites can be potentially applied to photodetectors and lithium ion batteries.Lastly, zinc germanate nanorods were synthesized through a hydrothermal process by using GeO2 and hydrate zinc acetate as germanium and zinc precursors respectively. Research results indicated that as crystal modifiers, oleylamine can lead to zinc germanate with high draw ratios while lactic acid can result in short zinc germanate nanorods. What’s more, pH is the key to hydrothermal synthesis of zinc germanate nanorods and only in weak alkaline environment can zinc germanate nanorods with high quality be obtained. Zinc germanate nanomaterials are potential photocatalysts according to their optical and electrochemical research results.