Facile fabrication of Ag-Pd bimetallic nanoparticles in ultrathin TiO2-gel films:: Nanoparticle morphology and catalytic activity
Facile fabrication of Ag-Pd bimetallic nanoparticles in ultrathin TiO2-gel films:: Nanoparticle morphology and catalytic activity
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DOI：
10.1021/ja035970b
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发表时间：
2003-09-10
影响因子：
15
通讯作者：
Toshima, N
中科院分区：
文献类型：
--
作者：
He, JH;Ichinose, I;Toshima, N
采用分步离子交换/还原法在TiO 2凝胶膜上直接制备了Ag-Pd纳米粒子。离子交换网站创建在SiO2膜使用Mg 2+离子作为模板。然后通过离子交换将Ag+离子引入，并通过低温H-2等离子体将其转化为金属纳米颗粒，再生离子交换位点。然后对Pd 2+离子进行相同的程序，产生Pd-on-Ag纳米颗粒，如TEM观察和等离子体共振吸收所示。相比之下，反向金属掺入程序似乎得到单个Ag和Pd纳米颗粒的混合物，如通过TEM、吸收光谱和X射线光电子能谱所证实的。对丙烯酸甲酯的加氢反应，Pd-on-Ag纳米粒子的催化活性是商品Pd黑的367倍，是单Pd纳米粒子的1.6倍。突出的催化活性是由表面暴露的Pd原子的大部分解释。讨论了纳米粒子的形成过程及其一般形态特征。
Ag-Pd bimetallic nanoparticles were prepared directly in ultrathin TiO2-gel films by a stepwise ion-exchange/reduction approach. Ion-exchange sites were created in ultrathin films using Mg2+ ions as template. Ag+ ion was then incorporated by ion exchange, and converted into metallic nanoparticles by low-temperature H-2 plasma, regenerating ion-exchange sites. The same procedure was then carried out for Pd2+ ion, producing Pd-on-Ag bimetallic nanoparticles, as TEM observation and plasmon resonance absorption indicate. By contrast, reversed metal incorporation procedure appeared to give a mixture of individual Ag and Pd nanoparticles, as confirmed by TEM, absorption spectroscopy and X-ray photoelectron spectroscopy. For hydrogenation of methyl acrylate, the catalytic activity of the Pd-on-Ag nanoparticle is 367 times as large as that of commercial Pd black and 1.6 times as large as that of Pd monometallic nanoparticle. The outstanding catalytic activity was explicable by the large fraction of the surface-exposed Pd atoms. The formation process of the bimetallic nanoparticle and their general morphological feature are discussed.