Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon, 305-701, Korea.
Langmuir. 2012 Apr 17;28(15):6441-7. doi: 10.1021/la300148e. Epub 2012 Apr 5.
The surface of Pd@SiO(2) core-shell nanoparticles (1) was simply modified by the formation of nickel phyllosilicate. The addition of nickel salts formed branched nickel phyllosilicates and generated pores in the silica shells, yielding Pd@SiO(2)-Niphy nanoparticles (Niphy = nickel phyllosilicate; 2, 3). By removal of the silica residue, Pd@Niphy yolk-shell nanoparticles (4) was uniformly obtained. The four distinct nanostructures (1-4) were employed as catalysts for Suzuki coupling reactions with aryl bromide and phenylboronic acid, and the conversion yields were in the order of 1 < 2 < 3 < 4 as the pore volume and surface area of the catalysts increased. The reaction rates were strongly correlated with shell porosity and surface exposure of the metal cores. The chemical inertness of nickel phyllosilicate under the basic conditions rendered the catalysts reusable for more than five times without loss of activity.
Pd@SiO(2)核壳纳米粒子（1）的表面通过镍硅酸盐的形成进行了简单修饰。添加镍盐会形成支化的镍硅酸盐，并在二氧化硅壳中产生孔，从而得到 Pd@SiO(2)-Niphy 纳米粒子（Niphy = 镍硅酸盐；2、3）。通过去除二氧化硅残留物，均匀地获得了 Pd@Niphy 蛋黄壳纳米粒子（4）。这四种不同的纳米结构（1-4）被用作芳基溴化物和苯硼酸的 Suzuki 偶联反应的催化剂，转化率的顺序为 1 < 2 < 3 < 4，随着催化剂的孔体积和表面积的增加。反应速率与壳的多孔性和金属核的表面暴露强烈相关。在碱性条件下，镍硅酸盐的化学惰性使催化剂在不失去活性的情况下可重复使用超过 5 次。
