Preparation And Characterization Of Core-Shell Structured Nickel And Iron Oxide By A Novel Liquild Phase Deposition Method

In recent years, there is an intense interesting in the fabrication of core/shell materials in the field of material science. Core-shell materials are known to exhibit unique and advanced properties than single-component materials. They also can be used as a precursor to prepare hollow spheres or to lower the cost of precious materials by coating them on inexpensive cores. The hard template method is one of the most effective approach to prepare core-shell materials. There are many merits such as simplicity, high repeating and being foreseeable for this method.Liquid Phase Deposition (LPD) method was widely used for preparing metal oxide films, but traditional LPD method has its own shortcomings of poor response flexibility. A novel LPD method was developed in this paper, in which metal(Fe,Ni) ion salt as the precursors and hydrofluoric acid solution as metal(Fe,Ni) ion ligands to form iron-fluoro and nickel-fluoro complex, ammonia hydroxide solution as hydroxyl ion suppliers and supplemental metal(Fe,Ni) ion ligands. SiO2 microspheres were prepared by hydrolyzing of Tetraethoxysilane(TEOS). Then, metal(Fe,Ni) oxide/silica core-shell microspheres were prepared by hydrolyze of metal ion ligands on the surface of SiO2. The hollow microspheres were obtained by reacting the core-shell microspheres with NaOH solution.The noval LPD method has many advantages: room temperature operation, simple production process, easy controlment, short period and low cost. In this paper,α-Fe2O3/SiO2 andα-Ni(OH)2/SiO2 core-shell micrespheres were prepared by this noval LPD method andα-Fe2O3 andα-Ni(OH)2 hollow microspheres wre successfully prepared by reacting with NaOH solution.The following influence conditions were discussed in this paper: solution pH values, coating times, and diameter of SiO2 microspheres. The prepared core-shell and hollow microspheres exhibited excellent mondispersibility, stabilization and large Brunauer-Emmett-Teller(BET) surface area.