Formation of Pt-Ru nanoparticles in ethylene glycol solution: An in situ X-ray absorption spectroscopy study
Formation of Pt-Ru nanoparticles in ethylene glycol solution: An in situ X-ray absorption spectroscopy study
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DOI：
10.1021/la0637418
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发表时间：
2007-05-08
期刊：
影响因子：
3.9
通讯作者：
Hwang, Bing-Joe
中科院分区：
文献类型：
--
作者：
Sarma, Loka Subramanyam;Chen, Ching-Hsiang;Hwang, Bing-Joe
采用原位x射线吸收光谱（XAS）研究了以乙二醇（EG）为还原剂合成的Pt-Ru纳米颗粒（NPs）的化学状态、形成机理及其稳定性。用EG还原Pt（IV）和Ru（III）前驱盐似乎不是一个简单的反应，而是涉及不同的中间步骤。将EG中含有Pt（IV）和Ru（III）前驱盐的反应混合物的pH控制在11，导致Pt（IV）还原为Pt(II)，对应于[PtCl4](2-)，而(RuCl3)- cl -III则变为[Ru(OH)(6)]（3-）。含有[PtCl4]（2-）和[Ru(OH)(6)]（3-）两种物质的混合物在160℃回流0.5 h，产生Pt-Ru NPs，这是由Pt和Ru在各自金属的第一配位壳中的存在所表明的。随着反应时间的增加，XAS的结构参数没有变化，说明形成的Pt-Ru NPs非常稳定，不易聚集。XAS结构参数表明最终的Pt-Ru np具有富pt核和富ru壳结构。由于EG还原法的固有优势，EG法合成的Pt-Ru NPs中Pt和Ru的原子分布和合金化程度高于改进Watanabe法合成的Pt-Ru/C NPs。
The chemical state and formation mechanism of Pt-Ru nanoparticles (NPs) synthesized by using ethylene glycol (EG) as a reducing agent and their stability have been examined by in situ X-ray absorption spectroscopy (XAS) at the Pt L-III and Ru K edges. It appears that the reduction of Pt(IV) and Ru(III) precursor salts by EG is not a straightforward reaction but involves different intermediate steps. The pH control of the reaction mixture containing Pt(IV) and Ru(III) precursor salts in EG to 11 led to the reduction of Pt(IV) to Pt(II) corresponding to [PtCl4](2-) whereas (RuCl3)-Cl-III is changed to the [Ru(OH)(6)](3-) species. Refluxing the mixture containing [PtCl4](2-) and [Ru(OH)(6)](3-) species at 160 degrees C for 0.5 h produces Pt-Ru NPs as indicated by the presence of Pt and Ru in the first coordination shell of the respective metals. No change in XAS structural parameters is found when the reaction time is further increased, indicating that the Pt-Ru NPs formed are extremely stable and less prone to aggregation. XAS structural parameters suggest a Pt-rich core and a Ru-rich shell structure for the final Pt-Ru NPs. Due to the inherent advantages of the EG reduction method, the atomic distribution and alloying extent of Pt and Ru in the Pt-Ru NPs synthesized by the EG method are higher than those of the Pt-Ru/C NPs synthesized by a modified Watanabe method.