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非常高的表面能，它们很容易相互聚集，从而失去基于纳米级颗粒尺寸的特征性质。本课题采用液相还原法，将<9nm的单纳米金属颗粒选择性沉积在各种载体表面，以防止纳米颗粒聚集。对所获得的纳米颗粒进行了详细的表征，以研究其物理和化学性质，并揭示其生长机制。研究了它们的催化活性，并与几种常规制备方法制备的镍催化剂进行了比较。(1) Ni-Zn纳米颗粒的选择性沉积及其生长机理Ni-Zn纳米颗粒成功地从液相还原到TiO_2颗粒（5-20nm）等载体上选择性沉积。对其生长机理的研究表明，金属配合物在载体上的吸附更多的是作为纳米粒子的核。在母液中加入Zn可以控制表面核的数目。因此，金属颗粒的粒度得到了精确的控制。(2)纳米镍的表征。采用HR-TEM、ESCA、EXAFS对纳米镍进行了表征。它揭示了：1；在母液中加入锌后，纳米镍颗粒的粒径减小。镍被成功还原为金属纳米粒子，而锌则以氧化态存在。(3)纳米镍的催化活性测定了纳米镍在1-辛烯和一氧化碳加氢反应中的催化活性。加入锌后，催化活性得到了很大的提高，这可能是由于锌的粒径较小。结果表明，金属纳米粒子通过沉积在载体（TiO_2）上，具有明显的稳定性，可以长时间保持其高催化活性。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