中文摘要：

在PEG-丙酮溶液体系中，采用紫外光辐射还原Au（Ⅲ），Pd（Ⅱ）离子混合物和以Au晶种为核、紫外光辐射还原Pd（Ⅱ）使其沉积在Au晶种表面上这两种方法，合成了Au核@Pd壳复合纳米粒子．通过改变Au（Ⅲ）离子或Au晶种对Pd（Ⅱ）离子的摩尔比调节复合粒子的尺寸和Pd壳厚度，分别获得了直径范围为5．6～4．6nm和4．6～6．2nm的复合粒子．利用UV—Vis吸收光谱、TEM、HR—TEM和XPS等表征手段，证明了合成的纳米粒子为核-壳复合结构．研究了Au@Pd纳米粒子的直径随溶液中Au（Ⅲ）／Pd（Ⅱ）摩尔比的改变而变化的规律；对Au核向Pd壳的供电子作用以及复合粒子的光化学形成机理进行了讨论．

英文摘要：

The combined gold and palladium bimetallic nanoparticles were received significant attention because of their special catalytic properties and Surface-enhanced Raman scatterings. In this paper, we report a new synthesis of Au @ Pd core-shell composite nanoparticles by the photochemical method. The bimetallic nanoparticles with an Au core@ Pd shell composite structure were synthesized in PEG-acetone solution by UV photochemical reduction, using both approaches of simultaneous reduction of Au （Ⅲ ） and Pd （ Ⅱ ） ions and Au seeding growth in the presence of Pd （ Ⅱ ）. The bimetallic nanoparticles sizes obtained by two approaches are between 5.6-4. 6 and 4.6-6.2 nm, respectively. The sizes of composite particles and the thickness of the palladium shell can be tuned by varying molar ratio of Au （Ⅲ ） or Au （0） and Pd （ Ⅱ）. Based on the characterizations by UV-Vis, XPS, TEM and HR-TEM, an Au core@ Pd shell nanostructure was confirmed and a special changing tendency of the composite particle size with a changing of Au： Pd molar ratio was found. The effect of the Pd shell gaining d-electrons from the Au core and the mechanism of forming Au core @ Pd shell nanostructure were discussed.