Study On Preparation And Properties Of Iron Oxide

Iron oxides, as an abundant and eco-friendly material, have attracted many researchers’ attention in the field of new energy sources and environmental governance.In this thesis, a one-step and green approach was explored to prepare Fe3O4nanoparticles by using L-Cysteine as reducer and disperser, then Fe3O4nanoparticles were modified with stearic acid (SA) to form Fe3O4@SA core-shell nanocomposites. And hydrophobic/lipophilic performances of product were studied. We also prepared α-Fe2O3nanosheets and α-Fe2O3/Mn3O4nanocomposites by solvothermal method, the electrochemical properties of products as anodes of lithium battery were studied. The main contents are summarized as follows:1. Paramagnetic Fe3O4nanoparticles were synthesized using a one-step, economic and green approach by using L-Cysteine as reducer and disperser without any additional agent and the protection of inert gas. To get optimum conditions, we have designed orthogonal experiments with different reaction temperature and molar ration of n(Fe3+)/n(L-Cys) as main parameters.The results show that samples is black and possess the strongest Ms when the molar ratios of n(Fe3+)/n(L-Cys) is1:2.14at80℃. The core-shell Fe3O4@SA nanocomposites prepared could dispersed stably in the oil medium to form magnetic fluid and remove oil from the water surface due to their hydrophobic and lipophilic properties. Also, Fe3O4@SA nanocomposites could form monolayer on the water surface or films by means of Langmuir-Blodgett (LB) technology.2. The Orzo-like, disk-like and flake-like α-Fe2O3nanocomposites were prepared by a one-step solvothermal method. And their electrochemical propertieswere investigated. Theresults show that, the orzo-like α-Fe2O3nanocomposites exhibit an initial discharge rate capacity of789mAh/g as a kind of anode materials for lithium-ion batteries, but the cycle performance is poor. While the flake-like α-Fe2O3nanocomposites exhibit an initial discharge capacity of819mAh/g and a stable specific discharge capacity of354mAh/g up to20cycles. This indicate that the flake-like α-Fe2O3nanocomposites owns better electrochemical performance and high cycling stability than the orzo-like α-Fe2O3nanocomposites.3. The α-Fe2O3/Mn3O4nanocomposites were prepared by a one-step solvothermal method after dispersing the as-prepared Fe3O4nanoparticles in ethanol/glycol solvent system containing KMnO4. As anode materials for lithium ion batteries, the products show high first discharge capacities of1558mAh/g, and achieved reversible capacities of about528mAh/g after20cycles. The electrochemical measurements show that the Fe2O3/Mn3O4nanocomposites possess higher electrochemical performance and better cycling stability than the α-Fe2O3nanocomposites prepared in the last chapter. The combination of different inorganic materials could expand the research scope of the lithium battery anode materials.