Synthesis of alloy nanoparticle by liquid phase selective reductive deposition method and its catalytic application

由于金属纳米颗粒具有极高的表面能，基于其纳米尺度的颗粒尺寸，它们很容易相互聚集而失去其特有的性质。在本研究项目中，为了防止纳米颗粒的团聚，采用液相还原的方法在各种载体的表面选择性地沉积了单一的纳米金属颗粒(~lt；9 nm)。对得到的纳米粒子进行了详细的表征，研究了它们的物理化学性质，揭示了它们的生长机理。本文还考察了它们的催化活性，并与几种常规制备方法得到的镍催化剂进行了比较。(1)选择性沉积Ni-Zn纳米颗粒及其生长机理成功地将Ni-Zn纳米颗粒从液相中还原出来，选择性地沉积在载体上，如纳米二氧化钛(5-20 nm)。对其生长机理的研究表明，金属络合物吸附了…更多关于载体作为纳米颗粒的核的作用。研究还发现，在母液中加入锌可以控制表面的晶核数量。纳米镍颗粒的表征利用高分辨电子显微镜、电子能谱、EXAFS等手段对纳米镍颗粒进行了表征。结果表明：1.在母液中加入锌后，镍纳米粒子的尺寸减小。2.镍被成功还原为金属纳米粒子，而锌则以氧化物种的形式存在。(3)纳米镍粒子的催化活性评价了纳米镍粒子在1-辛烯和一氧化碳加氢反应中的催化活性。添加锌可以显著提高催化剂的催化活性，这可能是由于锌颗粒较小所致。研究还表明，金属纳米粒子通过沉积在载体(TiO2)上得到了显著的稳定，使其在较长时间内保持了较高的催化活性。较少

Since metallic nanoparticles have remarkably high surface energy, they easily aggregate each other to lose their characteristic properties based on their nano-scaled particle size. In this research project, single nano-sized metallic particles (<9nm) are deposited selectively on the surface of various supports by using the liquid phase reduction method in order to prevent the nano-sized particles from aggregation. The nanoparticles obtained are characterized in detail to investigate their physical and chemical properties and to reveal their growth mechanism. Their catalytic activities are also investigated and compared with those of nickel catalysts obtained by several conventional preparation methods.(1)Selective deposition of Ni-Zn nanoparticle and its growth mechanismNi-Zn nanoparticles were successfully reduced from the liquid phase to be deposited selectively on supports such as TiO_2 particles (5-20nm). The studies on their growth mechanism indicated that metal complexes adsorbed … More on the support act as a nuclei for a nanoparticle. It is also revealed that the number of nuclei on the surface can be controlled by the addition of Zn to mother liquid. As a result, the particle size of metallic particles was precisely controlled.(2)Characterization of nickel nanoparticlesThe nickel nanoparticles were characterized by using HR-TEM, ESCA, EXAFS. It was revealed :1.the size of nickel nanoparticle decreased by adding zinc to mother liquid.2.nickel was successfully reduced to be a metallic nanoparticle, while zinc existed as an oxidized species.(3)Catalytic activities of nickel nanoparticleThe catalytic activities of the nickel nanoparticles were estimated in the hydrogenation of 1-octene and carbon monoxide. The catalytic activities were highly improved by adding zinc presumably due to the smaller particle size. It was also indicated that the metallic nanoparticle was remarkably stabilized through the deposition onto the support (TiO_2) to maintain its high catalytic activity for a long time. Less