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Seed-Mediated Growth of Pt on High-Index Faceted Au Nanocrystals: The Ag Lining and Implications for Electrocatalysis
ACS Applied Nano Materials ( IF 5.3 ) Pub Date : 2021-08-23 , DOI: 10.1021/acsanm.1c01714
Debashree Roy 1 , Ranguwar Rajendra 1 , Pranav K. Gangadharan 2 , Ajmal Pandikassala 2 , Sreekumar Kurungot 2 , Nirmalya Ballav 1
Affiliation  

Bimetallic Au@Pt nanocrystals (NCs) offer a unique combination of plasmonic and catalytic properties and are a growing field of research. Herein, we report an unusual observation in the behavior of silver ions (Ag+), which was found to play a dominant role in dictating the Pt deposition in a seed-mediated growth method. While the literature is replete with various instances of Ag-assisted Pt deposition whereby higher concentration of Ag+ translates into a thicker Pt shell, in the present study, contradictory observations were made. In the presence of lower amounts of Ag+, thick Pt shells were visualized, while at higher concentrations of Ag+, the extent of Pt deposition via the galvanic replacement reaction was reduced. Additionally, the presence of Ag was deemed necessary for the Pt deposition to take place, either in the form of an underpotential deposition layer on the Au NCs or by introducing Ag+ in the growth solution. We have demonstrated our findings on two different Au NCs enclosed with high-index facets, concave cuboid, and elongated tetrahexahedra, which mirror similar observations and provide generality to our claim. To the best of our knowledge, the time required for Pt deposition on the Au core in the present work is the least among the reported seed-mediated routes. Furthermore, this work, besides presenting a facile and general route for the amalgamation of catalytic and plasmonic properties in hybrid Pt–Au NCs, sheds light on the mechanistic aspects of Ag-assisted wet-chemical generation of bimetallic Au@Pt NCs. The overall electrocatalytic performance of our Au@Pt NCs toward the oxygen reduction reaction was realized to be impressive.

中文翻译:

Pt 在高指数多面 Au 纳米晶体上的种子介导生长:Ag 衬里及其对电催化的影响

双金属 Au@Pt 纳米晶体 (NCs) 提供了等离子体和催化性能的独特组合,并且是一个不断发展的研究领域。在这里,我们报告了银离子 (Ag + )行为的一个不寻常的观察结果,发现它在指示种子介导的生长方法中的 Pt 沉积中起主导作用。虽然文献中充斥着各种 Ag 辅助 Pt 沉积的实例,其中较高浓度的 Ag +转化为较厚的 Pt 壳,但在本研究中,进行了相互矛盾的观察。在较低量的 Ag +存在下,可以看到厚的 Pt 壳,而在较高浓度的 Ag + 下,通过电置换反应的 Pt 沉积程度降低。此外,Ag 的存在被认为是发生 Pt 沉积所必需的,无论是在 Au NCs 上以欠电位沉积层的形式还是通过引入 Ag +在增长解决方案中。我们已经证明了我们在两个不同的 Au NC 上的发现,这些 Au NC 被高折射率面、凹立方体和细长的四面体包围,它们反映了类似的观察结果并为我们的主张提供了普遍性。据我们所知,在目前的工作中,Pt 在 Au 核上沉积所需的时间是报道的种子介导途径中最短的。此外,这项工作除了为混合 Pt-Au NCs 中催化和等离子体特性的融合提供了一种简单而通用的途径外,还揭示了 Ag 辅助湿化学生成双金属 Au@Pt NCs 的机制方面。我们的 Au@Pt NCs 对氧还原反应的整体电催化性能令人印象深刻。
更新日期:2021-09-24
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