Investigation of catalytic activity and atomic structure for core-shell nanoparticles

点击翻译按钮获取中文摘要

Au-Pd binary nanoparticles prepared by sonochemical technique were investigated by the analytical transmission electron microscopy, positron annihilation spectroscopy, zeta-potential, X-ray diffraction and catalytic activity reaction experiments. Also, the first principle calculation of Au/Pd slub model and nano clusters have been performed in order to estimate the stability of Au/Pd interface, its electron density and reactive energy between some molecules and Pd surface of core-shell nanoparticles.Following conclusions we reached(1) Au-Pd nanoparticles of same diameter with different thickness ratio of Au-core and Pd-shell were successfully produced by sonochemical reduction method. Alloy nanoparticles with same size of core-shell nanoparticles also have been synthesized by addition of another type of surfactant. Moreover, various kind of irradiation reduction, such as electron, gamma-ray and ion beam, experiments have been performed and successfully synthesized pure Au and Au-Pd nan … More oparticles.(2) It makes clear that Au-Pd nanoparticles synthesized by sonochemical method have perfectly phase separation and surface Pd thin lattice tend to expand. Moreover, it found that expanded Pd-shell lattice epitaxially grows on the fcc Au lattice and with the coherent Au/Pd interface structure.(3) It found by positron annihilation and zeta potential experiments that this lattice expansion near the surface is related to the surface electronic state of which dose not match between pure Au and Pd bulk.(4) From the first principle calculations, expanded Pd thin lattice grow on fcc Au lattice is stable around Au/Pd interface and its lattice space becomes narrow as the stacked Pd layers increases.(5) Another calculation shows following result: in an electronic state of LDOS (local density of state) around surface in core-shell structure it appears that shrinking and up shift of d-band takes places.We proposed that Pd lattice expansion is a very important factor as the peculiar catalytic activity of core-shell Au-Pd nanoparticle. Less