【作者】 葛志强； 齐利民；

【Author】 Zhiqinag Ge;Limin Qi;College of Chemistry and Molecular Engineering,Peking University;

【机构】 北京大学； 北京大学化学与分子工程学院；

【摘要】 树枝状金属纳米结构往往具有高表面积并暴露出高活性晶面,因而呈现出增强的电催化性能[1]。与单一钯金属纳米粒子相比,钯基双金属纳米粒子由于金属间的耦合作用往往能进一步提高其催化性能,因此近年来倍受关注[2,3]。如何实现具有高催化活性的超枝状钯基双金属纳米粒子的可控合成具有较大的挑战性。在本工作中,我们在接近室温的条件下借助阳离子表面活性剂的辅助作用,首次通过一步法合成得到结构新颖的Pd-Ag超枝状纳米球。图1所示的SEM和TEM照片表明,该超枝状纳米球的直径约为50-80nm,其中单个纳米线分支的直径约为5-7 nm。EDX表征结果显示,该纳米粒子含有Pd和Ag两种金属。研究发现,溶液中Ag+的参与是形成纳米线分枝的重要因素,而阳离子表面活性剂十二烷基三甲基溴化铵则有助于纳米线分枝生长为分散的纳米球。初步的氧还原电催化测试结果表明,该Pd-Ag超枝状纳米球具有优良的电催化活性,达到与商业Pt/C催化活性相近的水平,具有潜在的应用价值。更多还原

【Abstract】 Dendritic metal nanostructures with high surface areas and exposed active facets usually exhibit enhanced electrocatalytic activity.Compared with pure Pd nanocrystals,Pd-based bimetallic nanoparticles,which can improve the catalytic properties,have attracted more attention in recent years.However,it remains a challenge to develop novel synthetic methods to prepare hyperbranched Pd-based nanoparticles with high catalytic activity.In this study,we achieved the first one-step synthesis of Pd-Ag hyperbranched nanospheres with the assistance of a cationic surfactant at near room temperature.The Pd-Ag hyperbranched nanospheres had diameters about 50-80 nm,with irradiating branches about 5-7 nm in diameter.In this synthesis,the Ag+ ions largely contributed to the formation of nanowire branches and the cationic surfactant C12 TAB played a key role in the growth of the branches into discrete nanospheres.Preliminary electrochemical measurements showed that the obtained Pt-free nanospheres exhibited excellent electrocatalytic performance toward oxygen reduction reaction(ORR),which was comparable to that for the commercial Pt/C catalysts.更多还原