Magnetism And Application Of Fe₃N和fe₄N Composites Prepared From Organic Nitrogen Source

Apart from the excellent magnetism and stability,iron nitrides perform wide perspective and significance,due to their particular structure and chemical properties.Yet the relevant study is still at the initial stage and one important reason is the metastability,leading to the huge challenges in material fabrication.Thus,it is imperative to develop a flexible synthetization of iron nitrides,prompting their applications.Based on the analysis above,we design a series of precursors of Metal-Organics to fabricate the iron nitride composites with good magnetic performance in the optimized conditions.Besides,the probable mechanism of Iron-Organics precursors transferring into iron nitride composites is also investigated.A series of Iron-Organics precursors have been designed from the organic amines,which can be calcinated into Fe₃N/C and Fe₄N/C composites.The as-synthesized composites show the obvious core-shell structure with good magnetic behaviors.Besides,the further study shows the Fe-N coordination bonds play the crucial role in fabricating the iron nitrides and the doped carbon in crystal lattice is beneficial for adjusting the properties of materials.To further investigate the effect of organic functional groups to the fabrication of iron nitrides,some common organic functional groups with nitrogenhas been utilized to systemically study the effect to the preparation and magnetism of iron nitrides.It is shown that the amino can coordinate to Fe³⁺ions,transfering into Fe₃N/C and Fe₄N/C composites.Besides,the adjustment of the components and structure of the Fe³⁺-Amine precursors realizes the selective preparation of Fe₃N/C and Fe₄N/C composites.Moreover,the component,structure and spatial effect of organic part except the functional groups with nitrogen also have important influence on the component,structure and purity of products.We design a gas-phase synthesis ofε-Fe₃N sub-microrods from the ethanediamine.Theε-Fe₃N sub-microrods show the distinguishable quadrangular morphology,good saturation magnetization and stable dispersion in normal saline.The as-synthesizedε-Fe₃N sub-microrods perform typical T₂ property with the r₂relaxivity of 549.18 mM^-1s^-1,which is superior to the medical Fe₃O₄ contrast agent and can be regarded as a potential MRI contrast agent with a good study perspective.We also study the application of hydrogen generation induced by the visible light,hydrazine decomposition and oxygen reduction reaction of Fe₃N/C and Fe₄N/C composites.The as-synthesized Fe₃N/C composites show an average efficiency of31.2μmolg^-1h^-1 to generate the hydrogen gas in the range of the visible light.Besides,the Fe₃N/C composites can realized 100%decomposition of hydrazine in relatively low temperature range.Moreover,in the optimized condition,the Fe₄N/C composites show a 0.03 V onset potential and a-0.15 V ORR peak,performing a good ORR catalytic activity.