Fabrication and characterization of Ag/Pd colloidal nanoparticles as stable platforms for SERS and catalytic applications
Fabrication and characterization of Ag/Pd colloidal nanoparticles as stable platforms for SERS and catalytic applications
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DOI：
10.1016/j.matchemphys.2015.10.029
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发表时间：
2015-11-01
影响因子：
4.6
通讯作者：
Giorgetti, Emilia
中科院分区：
文献类型：
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作者：
Muniz-Miranda, Maurizio;Caporali, Stefano;Giorgetti, Emilia
我们通过在纯水中脉冲激光烧蚀Ag和连续添加硝酸Pd（II）的电替换，制备了稳定的Ag/Pd胶体，作为sers活性和催化平台。除了紫外可见吸收和微观表征外，我们还进行了XPS测试，通过使用不同的Ar溅射时间，可以评估纳米颗粒中的Pd/Ag比率，并确认TEM分析结果。在银/钯胶体悬浮液中进行的拉曼测量可以评估其SERS活性。我们评估了钯银比和获得稳定的双金属胶体所需的时间。银胶体老化对其与Pd（II）离子反应性的影响可以用吸附在银粒子表面的带电物质诱导的效应来解释。这一过程是通过观察到的银胶体的ζ电位的时间演变来描述的。最后，我们通过SERS监测Pd诱导的2-氨基，5-硝基吡啶的硝基还原，随后形成2,5-二氨基吡啶，证明了我们的Ag/Pd纳米结构的双重功能。这些银/钯胶体颗粒可以通过SEAS测量来观察纳米级钯诱导的反应，而不会受到残留还原剂或副产物的干扰，而化学途径获得的金属胶体可能会发生这种情况。(C) 2015 Elsevier B.V.版权所有
We prepared stable Ag/Pd colloids to be used as both SERS-active and catalytic platforms by combining pulsed laser ablation of Ag in pure water and galvanic replacement with a successive addition of Pd(II) nitrate. Beyond UV-vis absorption and microscopic characterization, we also performed XPS tests that, by utilizing different Ar sputtering times, permitted to evaluate the Pd/Ag ratio in the nanoparticles and to confirm the results of the TEM analysis concerning their structure; Raman measurements performed in Ag/Pd colloidal suspensions allowed evaluating their SERS activity. We assessed both the Pd/Ag ratio and the timing that are required to obtain stable bimetallic colloids. The influence of the Ag colloid ageing on its reactivity with Pd(II) ions has been explained by the effects induced by the adsorbed charged species on the surface of the silver particles. This process is described by the observed temporal evolution of the zeta-potential of the Ag colloid. Lastly, we demonstrated the double functionality of our Ag/Pd nanostructures by SERS monitoring the Pd-induced catalytic reduction of the nitro group of 2-amino, 5-nitropyridine with subsequent formation of 2,5-diaminopyridine. These Ag/Pd colloidal particles allowed observing reactions induced by nanosized palladium by SEAS measurements, without interference of residual reducing agents or by-products, as instead could occur for metal colloids obtained by chemical routes. (C) 2015 Elsevier B.V. All rights reserved.