铸态及快淬态CeMg10Ni2合金电化学储氢热力学及动力学性能研究

为了改善CeMg₁₀Ni₂合金的电化学储氢性能,快淬技术被用来制备具有非晶纳米晶结构的CeMg₁₀Ni₂合金. 运用X射线衍射及高分辨透射电镜对合金的微观结构及其相组成进行分析. 通过恒电流充放电、高倍率放电、交流阻抗以及动电位极化测试对合金的电化学性能进行了详细研究. 研究结果表明,铸态合金由多相结构组成,经过快速凝固处理的合金内部含有大量的非晶纳米晶结构,而且增加的凝固速度可以增强合金内部的非晶纳米晶形成能力. 快速凝固处理减小了合金的热力学参数（ΔH和ΔS）,降低了合金氢化物的热稳定性,改善了电化学放电容量. 另外,快速凝固处理显著改善了合金的电化学动力学性能,合金的表观活化能变化进一步解释了这一结论.     

核壳结构镍的制备及催化性能

利用软化学方法制备出了聚苯乙烯(PS)/镍核壳结构和纳米镍催化剂, 并利用SEM和XRD对材料的形貌和结构进行了表征. 将上述催化剂应用于亚甲基蓝染料加氢反应, 一步实现染料褪色和硼氢化钠水解制氢. 研究表明, 核壳结构极大地提高了镍的催化能力. 在相同条件下, 核壳结构镍的加氢催化效率是纳米镍的1.42倍, 产氢效率是纳米镍的4.76倍, 这说明核壳结构在催化领域具有一定的优势.     

Role of Microstructure and Spectrum Features on the Catalysis Effect of Ce_(1-x)(Nd_(0.5)Eu_(0.5))_xO_(2-δ) Solid Solutions

Nanosized Ce_(1-x)(Nd_(0.5)Eu_(0.5))xO_(2-δ) solid solutions(x = 0.00~0.20) were synthesized by means of hydrothermal method.Then the solid solutions were ball milled with Mg_2Ni and Ni powders for 20 h to get the Mg_2Ni–Ni–5 mol% Ce_(1-x)(Nd_(0.5)Eu_(0.5))xO_(2-δ) composites.The structures and spectrum characteristics of the Ce_(1-x)(Nd_(0.5)Eu_(0.5))xO_(2-δ) solid solutions catalysts were analyzed systemically.XRD results showed that the doped samples exhibited single phase of CeO_2 fluorite structure.The cell parameters and cell volumes were increased with increasing the doped content.Raman spectrum revealed that the peak position of F_(2g) mode shift to higher wavenumbers and the peak corresponding to oxygen vacancies were observed distinctly for the doped samples.UV-Vis technique indicated that the absorption peaks of Eu~(3+) and Nd~(3+) ions appeared; the bandgap energy was decreased linearly.The electrochemical and kinetic properties of the Mg_2Ni–Ni–5 mol% Ce_(1-x)(Nd_(0.5)Eu_(0.5))xO_(2-δ) composites were measured.The maximum discharge capacity was increased from 722.3 mA h/g for x = 0.00 to 819.7 mA h/g for x = 0.16,and the cycle stability S_(20) increased from 25.0%(x = 0.00) to 42.2%(x = 0.20).The kinetic measurement proved that the catalytic activity of composite surfaces and the hydrogen diffusion rate were improved for the composites with doped catalysts,especially for the composites with x = 0.16 and x = 0.20.The catalysis mechanism was analyzed from the point of microstructure and spectrum features of the Ce_(1-x)(Nd_(0.5)Eu_(0.5))xO_(2-δ) solid solutions.