【摘要】 系统研究了贵金属引导还原法制备Au-Ni异质结纳米晶中的尺寸控制规律,并通过TEM、紫外-可见光谱对样品进行了表征.研究表明:在240℃条件下,Au-Ni异质结的合成过程中,减少Au前驱体用量,并不能减小异质结中Au端颗粒的尺寸,此时其尺寸保持不变而Ni端颗粒的尺寸明显增大;在反应体系中引入适量的双十二烷基二甲基溴化铵(DDAB)会使异质结Au端颗粒尺寸相应减小,同时Ni端颗粒尺寸保持不变,进而实现异质结两端颗粒尺寸的选择性调控.要实现Au、Ni端颗粒尺寸的同时减小需降低反应温度,但一定范围内的升高温度则不会产生明显作用.以上研究不单提供了纳米异质结的调控方法,也为进一步研究Au-Ni双金属纳米晶的催化等性能打下了材料基础.更多还原

【Abstract】 Size control of Au-Ni heteronanostructure in synthesis was systematically studied in this paper.Monodispersed Au-Ni spindly nanostructures were obtained through noble-metal-induced-reduction(NMIR) strategy.In a typical synthesis,0.05 g of HAuCl4 and 0.25 g of Ni(NO3)2 6H2 O were added into 10 mL of octadecylamine(ODA) at 120 ℃.Then,the system was heated to 240 ℃;under this temperature,products were synthesized after 10 min of magnetic stirring.The products were collected by centrifugation and purified by washing with ethanol for several times.Transmission electron microscopy(TEM) and UV-Visible spectroscopy(UV-vis) were applied to characterize the morphology and size of the as obtained heteronanostructures.Results indicated that the size of Ni tip would increase when the quantity of gold precursor was reduced,while the size of Au tip would not change;it might result from the unchanged temperature which kept the size of Au tip being the same,but comparatively more Ni precursor led to continuous growth on Au nanocrystals.Besides,halogen ions could also tune the size of Au-Ni tips by bring down the surface energy of noble metal nanocrystals,when bromide-ions-containing didodecyldimethylammonium bromide(DDAB) was introduced to the system,Au particle in spindly nanostructures turned out to be smaller while the Ni size remained unchanged,and thus achieving the controllable regulation of both tips of the Au-Ni heteronanostructure under synthetic temperature of 240 ℃.To reducing both Au size and Ni size of the particles simultaneously,lower temperature in the initial reaction stage was used,but little rising of initial temperature did not produce remarkable changes of the size of Au-Ni heteronanostructure.This work not only provides a method for the size control of heteronanostructures,but also leads the material foundation for the further study of the catalytic performance of the Au-Ni bimetallic nanocrystals.更多还原