Hollow bimetallic nanoparticles generated in situ inside a polymer thin film: fabrication and catalytic application of silver–palladium–poly(vinyl alcohol)
Hollow bimetallic nanoparticles generated in situ inside a polymer thin film: fabrication and catalytic application of silver–palladium–poly(vinyl alcohol)
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DOI：
10.1039/c3ta12807e
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发表时间：
2013-10
影响因子：
--
通讯作者：
V. K. Rao;T. Radhakrishnan
中科院分区：
文献类型：
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作者：
V. K. Rao;T. Radhakrishnan
采用两步法在聚乙烯醇(PVA)薄膜中原位制备了中空的银-钯双金属纳米颗粒(Ag-Pd)。在第一阶段，通过对旋涂薄膜进行温和的热处理来制备Ag-PVA，聚合物既是嵌入的金属前驱体离子的还原剂，又是生成的纳米粒子的稳定剂。在第二阶段中，在常温下将氯化钯钾水溶液(K2PdCl4)铺展在薄膜上，然后通过电偶置换反应将钯沉积在银纳米颗粒上并与其合金化。在第二阶段可以作为牺牲模板的相对较大的银纳米颗粒的关键要求通过在第一阶段中添加催化量的铜离子来满足。在原位过程中使用的K2PdCl4溶液浓度的逐渐变化使得系统地展示了双金属纳米颗粒的演变，最终形成了具有Ag-Pd合金壁的中空颗粒。Ag-Pd中空纳米粒子包埋PVA薄膜在Suzuki-Miyaura反应中的应用证明了其高催化效率。
Hollow bimetallic nanoparticles of silver–palladium (Ag–Pd) are generated in situ inside poly(vinyl alcohol) (PVA) thin films by a two-stage process. In the first stage, Ag–PVA is fabricated by mild thermal treatment of a spin-coated thin film, with the polymer functioning as the reducing agent for the embedded metal precursor ions as well as the stabilizer for the generated nanoparticles. In the second stage, an aqueous solution of potassium palladium chloride (K2PdCl4) is spread on this film under ambient conditions, whereupon Pd gets deposited on the Ag nanoparticles through a Galvanic displacement reaction and alloys with it. A crucial requirement of relatively large Ag nanoparticles that can act as the sacrificial template in the second stage is met by the addition of catalytic amounts of cupric ions in the first stage. A gradual variation of the concentration of K2PdCl4 solution used in the in situ process allowed a systematic demonstration of the evolution of the bimetallic nanoparticles with the eventual formation of hollow particles with Ag–Pd alloy walls. The high catalytic efficiency of the Ag–Pd hollow nanoparticle-embedded PVA thin film is demonstrated by its application in the Suzuki–Miyaura reaction.