Chemical Modification And Electrochemical Properties And Gas-Sensitive Study Of Magnetic Nano-Fe₃O₄

Nano-Fe₃O₄is more widely applied in practical production due to its specialphysicochemical properties, low-price and pollution-free. The study on single Fe₃O₄nanoparticles cannot satisfy the desire for knowledge of scientists. Surface modification ofnano-Fe₃O₄particles by inorganic matter, which attracts more and more researchers. Usingcoating technology to reach the purpose of changing the nano-Fe₃O₄particles of surfaceproperties, such as, surface charge, functional groups and reaction characteristics, whichcan improve the stability and dispersion of core. Nuclear material exhibits excellentproperties in electricity after introducing the shell materials.The study on the surface modification of nano-Fe₃O₄is divided into three parts. Firstly,the surface of Fe₃O₄microsphere coated with a layer of SiOx to produce Fe₃O₄/SiO_Xcore/shell nano-particles. Secondly, the Fe₃O₄/NSO particles coated with silicate layerstructure was obtained from the Fe₃O₄/SiO_Xprecursors. Finally, the α-Fe₂O₃were formedthrough a hydrothermal route based on a Fe₃O₄/SiO_Xsacrificial templating process.The Fe₃O₄Nano-particles with the average size of abount50nm were prepared byusing chemical oxidation method, and the particles were crystalline and well dispersed,the saturation magnetization is75emu/g, coercivity is90Oe, the specific capacitancereached35.4F/g. This silica coating step by a modified Stober’s process is highlyreproducible, the shell thickness is about20nm and the specific capacitance is34.6F/g. Bythe hydrothermal method, the average size of the Fe₃O₄/NSO particles is about120nm, theshell thickness is about70nm and the specific capacitance reached94.2F/g. The flakyα-Fe₂O₃were formed through a hydrothermal route based on a Fe₃O₄/SiO_Xprecursor andintroducing ferric ion.The width of the flake-shape α-Fe₂O₃is about50nm and the thicknessis approximately5nm.The specific capacitance reached94.2F/g. The flake-shape α-Fe₂O₃have high gas seNSOitive property with ethanol and acetone, it exhibited the bestgas-sensoing property to ethanol at290℃, the gas sensoitive property of the sampleincreased with the rise of temperature toacetone.