First-principles kinetics study of carbon monoxide promoted Ostwald ripening of Au particles on FeO/Pt(111)

The dynamic and kinetic evolution of supported metal particles in the presence of reactants is decisive in shaping the nature of the catalytic active sites and the deactivation process. Ostwald ripening of FeO/Pt(111) supported Au particles in the presence of carbon monoxide is addressed here by firstprinciples kinetics. It is found that CO stabilizes the ripening monomer(Au atom) by forming favorable Au carbonyls with lower total activation energy, and corresponding phase diagram at wide range of temperature and CO pressures is constructed. Evolution of particle number, dispersion and particle size distribution of supported Au particles are explored. Great influence of CO promotion on ripening kinetics is revealed and explored in details, and mbar range of CO can lower the onset temperature of ripening by a few hundred kelvins. The present work reveals the crucial role of the metal-reactant complexes formed under reaction conditions on ripening of metal catalysts.

盐酸羟胺还原法制备Fe_3O_4/Au磁性纳米复合微粒

Fe3O4/Au磁性纳米复合微粒由于具有一些奇异的物理特征而被广泛的应用于各个领域。因此,有关磁性纳米复合颗粒的制备已成为目前的一个研究热点。实验中用还原法制备了Fe3O4/Au纳米复合微粒,通过扫描电子显微镜对其表面形貌进行了观测,结果表明,制备的FeO/Au纳米复合微粒呈球形,颗粒间没有明显团聚,大小均匀,分散性好。