Controlled Synthesis Of ?-Fe₂O₃ Nanomaterials And Its Composites For Application

Nanoparticles with different surface environment,microstructures and morphologies may have a great influence on their properties.Hence,it will be meaningful to improve the performance by building the relationship of morphologies and properties of as-prepared materials that were obtained through controlled synthesis.Based on the advantage of liquid-liquid interface approach,herein,we proposed a very simple one-step n-octanol/water interface reaction for the controlled synthesis of series of ?-Fe₂O₃ nanostructures.What's more,the nanocomposites of?-Fe₂O₃/GN and ?-Fe₂O₃/GN/Ag were also synthesized on this basis.The formation mechanism of the ?-Fe₂O₃ nanomaterials was investigated,and the magnetic,photocatalytic,electrochemical and gas sensing properties of the ?-Fe₂O₃ nanomaterials and its composites were also researched in detail.The main research works are shown as follows:1.A series of ?-Fe₂O₃ nanomaterials with controlled morphologies?hollow ellipsoids,nanocup and octahedraln nanomaterials?were synthesized by a simple liquid-liquid interface reaction.The results indicated that the solvent ratio of n-octanol vs deionized water,concentration of reactants and reaction temperature all play important roles in preparing different morphologies of ?-Fe₂O₃ nanomaterial.And also,n-octanol was assumed to have multiple functions such as solvent,surfactant,and forming a liquid-liquid interface with water.The as-obtained product showed good magnetic and photocatalytic properties.Compared to the hollow structure,the coercivity of the nanomaterial with octahedra structure is much higher?up to 40000e?.The nanocup and small-size octahedra nanostructures exhibit better visible-light photocatalytic properties towards RhB?up to ca.95%?.As to 1000ppm of acetone gas,the maximum gas sensitivity is up to 32.55 for the sample synthesized in a typical experiment.2.?-Fe₂O₃ nanorods were synthesized via a simple liquid-liquid interface reaction and sequential calcinations using FeCl₃·6H₂O as the only source materials,where a mixture of n-octanol and water was used as solvent.A series of morphologies of the products?nanocube,nanoplate etc?can be easily adjusted by controlling the reaction parameters such as the solvent,concentration of the reactants and additives etc.In order to improve the electrochemical performance,?-Fe₂O₃ nanorod/GN was synthesized via a common reduction method.Compared with ?-Fe₂O₃ nanorods,the electrochemical performance of ?-Fe₂O₃/GN nanocomposites has been improved significantly.The discharge capacity of nanocomposites was up to 1101 mA h g-1 and the reversible capacity was 58%,and it can still be maintained after 100 cycles at a current density of 0.1C.At a rate of 0.5C,the specific capacity of ?-Fe₂O₃/GN is up to 345 mAh g-1,25 times higher than that of ?-Fe₂O₃ nanorods.3.In order to improve the photocatalytic performance of the product,the?-Fe₂O₃/GN/Ag nanocomposites were synthesized via a reduction method.The prepared silver nanoplates were loaded on the composite of ?-Fe₂O₃/GN to form a novel ?-Fe₂O₃/GN/Ag nanocomposite.The photocatalytic behaviour was improved as the synergistic effect of components,effectively enhancing the absorbance of visible light and the separation of photocharges from vacancies on the surface.Compared to?-Fe₂O₃ nanorods and ?-Fe₂O₃ nanorod/GN,the relative degradation rate of hematite/GN/Ag nanocomposites has been improved,up to 91%in 60min,1.65 and 1.34 times to that of ?-Fe₂O₃ nanorods and ?-Fe₂O₃ nanorod/GN,respectively.