论文-铁钴镍基二元合金微纳米结构控制合成磁学催化性能

1、-铁钴镍基二元合金论文：铁钴镍基二元合金微纳米构造的控制合成、磁学及催化性能【中文摘要】磁性合金材料作为一类重要的功能材料,引起了科学家的广泛关注,并在很多领域得到广泛的应用,如:磁流体、催化、生物科技和生物医药、磁共振成像、数据存储、环境治理等领域。而纳米材料的性能常常受其尺寸、形貌和组成的影响,因此,可控制合成磁性微纳米材料与性能研究成为了化学和材料学研究的重要领域之一。本论文旨在开展不同的合成方法制备具有不同形貌、尺寸和组成的铁钴镍基二元合金微纳米材料,同时,对其形成机理、相关磁学性能和在对硝基苯酚【英文摘要】Magnetic alloys materials are very impo

2、rtant functional materials, which have attracted e*tensive attention because of their special physical, chemical properties and their potential applications in ferrofluids, magnetic resonance imaging, biotechnology, biomedicine, data storage, catalytsis, and environmental remediation, etc., and whic

3、h strongly depended on their size, morphology, position, and structure etc. In this thesis, we focused on developing different methods to synthesize magnetic binary alloys micro-/nanostructures based on Fe, Co and Ni with different morphologies, sizes, and positions. At the same time, their formatio

4、n mechanism, magnetic properties, and catalytic applications in reduction of 4-Nitrophenol were studied. The main contents and major results are given as follows:1. Uniform-sized, monodisperse, and single crystalline 3-dimensional NiCo2 dendritic microstructures were successfully synthesized in high

5、 yield by a simple and facile solution phase route in presence of CTAB. By adjusting the e*perimental parameters NiCo alloys nanostructures with different morphologies, sizes, and positions were controllable synthesized, at the same time, the formation mechanism was investigated. While NiCo2 alloys

6、micro-structure with shapes of sphere-like and flower-like were prepared by hydrothermal and solvothermal methods, respectively. Magnetic measurements revealed that all of the NiCo2 alloys obtained are ferromagnetic at room temperature. The saturation magnetization value of the Ni33.8Co66.2 dendrite

7、s 163.55 emu/g is lower than that of the Ni32.3Co67.7 spheres 212.29 emu/g and Ni33.4Co66.6 flower-likes 195.79 emu/g, but the Ni33.8Co66.2 dendritic structures e*hibit an enhanced coercivity value. NiCo2 alloys with different shapes (Ni33.8Co66.2 dendrites, Ni33.4Co66.6 flower-likes and Ni32.3Co67.

8、7 spheres) have been used as reusable heterogeneous catalysts to reduce 4-nitrophenol 4-NP into 4-aminophenol 4-AP by NaBH4. From the average reaction rate constants at three different temperatures, we determined the activation energy, the entropy of activation, and the pre-e*ponential factor for ea

9、ch shape of NiCo2 alloys. The kinetic data indicate that Ni33.8Co66.2 dendrites are catalytically more active than that of both the Ni33.4Co66.6 flower-likes and Ni32.3Co67.7 spheres probably due to its largest surface-to-volume ratio and surface areas.2. The Ni-based metals, such as Ni, and FeNi al

10、loy nanostructures with different shapes were synthesized by solvothermal method in polyol system. The reaction parameters such as reaction time, the concentration of NaOH, temperature, solvent, and the initial concentration of metals ions that affected the morphology of FeNi alloys were investigate

11、d systematically. When we changed the type of solvents, the Ni nanostructures with chain-like were obtained, and the possible formation mechanism was also discussed. Magnetic data show that all of the Ni and FeNi2 alloys obtained are ferromagnetic at room temperature. The saturation magnetization va

12、lue of the Fe34.8Ni65.2 spheres with size of ca. 300 nm 174.62 emu/g is higher than that of the Fe34.1Ni65.9 spheres with size of ca. 230 nm 166.71 emu/g and Fe33.5Ni66.5 spheres with size of ca. 170 nm 160.05 emu/g, but the Fe33.5Ni66.5 spheres ca. 170 nm e*hibit an enhanced coercivity value. The s

13、aturation magnetization value of the chain-like Ni nanostructures 68.3 emu/g is lower than that of flower-like Ni nanostreutures 84.9 emu/g, but all higher than that of the bulk nickel 55 emu/g. Especially, the flower-like Ni nanostructures e*hibit an enhanced coercivity value ca. 204.81 Oe. At last

14、, the FeNi2 alloys with three different sizes were applied to reduce the 4-Nitrophenol to 4-Aminophenol by NaBH4 in aqueous solution, and the reaction rate constants were obtained. The kinetic data indicate that Fe33.5Ni66.5 nanospheres ca. 170 nm are catalytically more active than that of both the

15、Fe34.1Ni65.9 nanospheres ca. 230 nm and Fe34.8Ni65.2 nanospheres ca. 300 nm probably attribute to its smallest size, which induces the largest surface-to-volume ratio and surface areas. The BET3. Crystalline FeCo alloys Fe59Co41, Fe37Co63 nanoparticles in diameter of 6?12 nm were synthesized by redu

16、ction of FeCl3 with hydrazine under ultrasonic wave, which is a simple, low-cost, surfactant-free route, and may stimulate technological interests. The reaction parameters such as temperature, the total concentration of Fe3+ + Co2+, and the initial ratio of Fe3+/Co2+ that affected the FeCo sizes and

17、 morphologies were investigated systematically. As-synthesized Fe59Co41 nanocrystallite shows e*cellent soft magnetic behaviour with high saturation magnetization up to 216.2 emu/g that is parable with that of bulk Fe and Fe60Co40 alloy, and could have applications in catalysis, biotechnology, and m

18、agnetic storage devices.4. The metals/r-graphene and alloys/r-graphene hybrid materials, such as Ni/r-graphene, Co/r-graphene, Cu/r-graphene, NiCo/r-graphene, FeCo/r-graphene, FeNi/r-graphene, CoCu/r-graphene and NiCu/r-graphene hybrid materials were successfully synthesized by a fiacle two steps me

19、thod used hydrazine as reduction reagent. The samples were characterizated by SEM, TEM, HRTEM, *RD, ED*, and ICP, respectively, the results shown that the nanoparticles were uniform dispersed on the surface of the graphene sheets. The reaction parameters such as reaction time, the concentration of m

20、etals ions, the modified of graphene, and the added sequence of the materials that affected the formation of hybrid materials were investigated systematically, based on which possible formation mechanism for the hybrid materials was proposed. The room temperature magnetic properties were characteriz

21、ated by SQUID MPMS *L-7, the metal or alloy/r-graphene hybrid materials e*hibited an enhanced saturation magnetization or coercivity. At last, the reduction of 4-NP to 4-AP were carried out used five different materials as catalysts. The rate constants of the five catalysts is 5.82×10-3 S-1S1,

22、Ni/r-graphene, 4.63×10-3 S-1S2, Ni/r-graphene, 4.95×10-3 S-1S3, Ni/r-graphene, 2.60×10-3 S-1r-graphene, 3.50×10-3 S-1Ni nanoparticles, 4.15×10-3 S-1the mi*ture of Ni nanoparticles and r-graphene, respectively. Here, the r-graphene shows a good catalytic property for this red

23、uction reaction, which was needed further investigation.【关键词】铁钴镍基二元合金 微纳米构造 磁性材料 控制合成 催化应用 复合材料 石墨烯【英文关键词】Fe, Co and Ni-based binary alloy Micro-/Nanostructure Magnetic materials Controlled-synthesis Catalytic application posite materials Graphene【目录】铁钴镍基二元合金微纳米构造的控制合成、磁学及催化性能摘要5-8Abstract8-10第一章 绪言

24、13-261.1 引言13-171.1.1 液相复原法14-151.1.2 水热/溶剂热法15-161.1.3 超声化学合成法16-171.2 论文选题意义及论文设想17-181.2.1 论文选题目的及意义171.2.2 论文研究容17-18参考文献18-26第二章 镍钴合金磁性微纳米合金材料的制备及其催化应用研究26-572.1 引言26-272.2 实验局部27-282.2.1 试剂与仪器272.2.2 样品制备27-282.2.3 样品表征282.3 结果与讨论28-412.3.1 NiCo_2枝茎样品的形貌和构造分析28-382.3.2 花状Ni_(33.4)Co_(66.6)合金构造的分析38-392.3.3 球状Ni_(32.3)Co_(67.7)合金构造的分析39-402.3.4 不同形貌的NiCo_2合金微构造的磁学性能40-412.4 不同形貌的镍钴合金在对硝基苯酚催化中的应用41-452.4.1 催化实验412.4.2 催化可行性分析以及催化过程的跟踪41-422.4.3 催化结