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学科主题物理化学
A general approach to synthesize thermally stable and highly active Au-Ag alloy nanoparticles supported on inert supports
Liu XY(刘晓燕); Wang AQ(王爱琴); Li L(李林); Zhang T(张涛); Tao Zhang
会议名称GOLD 2009(The 5th international conference on gold science, technology and its applications)
会议日期2009-7-26
2009-07-26
会议地点德国
其他题名一种在惰性载体上制备高热稳定性高活性的Au-Ag合金纳米粒子的通用的方法
页码192/1
部门归属十五室
主办者世界金协会,海德堡大学
英文摘要It has been widely accepted that the particle size of the supported gold catalysts plays a key role in determining the catalytic performances. Generally, small-sized gold nanoparticles are obtained on active supports (TiO2, Fe2O3, Co3O4, etc.) by deposition-precipitation (DP) or co-precipitation (CP) method. While on inert supports such as silica, it still remains a challenge to prepare highly dispersed gold nanoparticles. In this work, we developed a general two-step method to prepare small-sized (~ 3 nm), thermally stable, and highly active Au-Ag alloy nanoparticles supported on inert supports such as commercial silica, Al2O3 and SBA-15. In this two-step method, AuCl4- ions were first adsorbed on amine-modified silica surface and reduced by NaBH4 to form small-sized gold particles. Then, Ag+ cations were allowed to adsorb on the negatively-charged gold surface. The recovered solid was calcined at 500 oC in air and reduced at 550 oC in H2 to obtain the supported Au-Ag alloy nanoparticles. Ultraviolet-visible spectroscopy (UV-vis) and high-resolution transmission electron microscopy (HRTEM) were employed to trace the each preparation step for exploring the formation mechanism of the Au-Ag alloy nanoparticles. The results show that silver plays an important role in stabilizing the particles. During the high-temperature calcination in air, a thin layer of silver oxide species forms on the surface of the gold nanoparticles, serving as a passivating agent and preventing the aggregation of the nanoparticles. The high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image in Figure 1 clearly shows that the Au-Ag alloy nanoparticles supported on the commercial silica are very small and uniform. More intriguing, they are highly stable against the high temperature calcinations. Such-prepared Au-Ag/SiO2 catalyst exhibited very high reactivity in low-temperature CO oxidation, even comparable with that of the Au/TiO2 which is one of the most active gold catalysts. In conclusion, we developed a general strategy to obtain small-sized, thermally stable and highly active Au-Ag nanoparticles on commercially available silica and alumina supports. We believe this method can be extended to a variety of other supports with rich hydroxyl groups on their surfaces. This strategy of stabilizing the gold particles by alloying with a second metal paves a novel way for controlling the particle sizes and for enhancing the thermal stabilities of gold particles, in particular on those inert supports.
语种中文
文献类型会议论文
条目标识符http://cas-ir.dicp.ac.cn/handle/321008/113526
专题中国科学院大连化学物理研究所
通讯作者Tao Zhang
推荐引用方式
GB/T 7714
Liu XY,Wang AQ,Li L,et al. A general approach to synthesize thermally stable and highly active Au-Ag alloy nanoparticles supported on inert supports[C],2009:192/1.
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