Nayak Chandrani, Bhattacharyya D, Bhattacharyya K, Tripathi A K, Bapat R D, Jha S N, Sahoo N K
Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
J Synchrotron Radiat. 2017 Jul 1;24(Pt 4):825-835. doi: 10.1107/S1600577517006257. Epub 2017 May 18.
Au-Pt bimetallic nanoparticles have been synthesized through a one-pot synthesis route from their respective chloride precursors using block copolymer as a stabilizer. Growth of the nanoparticles has been studied by simultaneous in situ measurement of X-ray absorption spectroscopy (XAS) and UV-Vis spectroscopy at the energy-dispersive EXAFS beamline (BL-08) at Indus-2 SRS at RRCAT, Indore, India. In situ XAS spectra, comprising both X-ray near-edge structure (XANES) and extended X-ray absorption fine-structure (EXAFS) parts, have been measured simultaneously at the Au and Pt L-edges. While the XANES spectra of the precursors provide real-time information on the reduction process, the EXAFS spectra reveal the structure of the clusters formed in the intermediate stages of growth. This insight into the formation process throws light on how the difference in the reduction potential of the two precursors could be used to obtain the core-shell-type configuration of a bimetallic alloy in a one-pot synthesis method. The core-shell-type structure of the nanoparticles has also been confirmed by ex situ energy-dispersive spectroscopy line-scan and X-ray photoelectron spectroscopy measurements with in situ ion etching on fully formed nanoparticles.
通过一锅合成法，以嵌段共聚物为稳定剂，从各自的氯化物前驱体合成了金-铂双金属纳米颗粒。在印度印多尔RRCAT的Indus-2 SRS的能量色散EXAFS光束线（BL-08）上，通过同时原位测量X射线吸收光谱（XAS）和紫外可见光谱，研究了纳米颗粒的生长情况。原位XAS光谱包括X射线近边结构（XANES）和扩展X射线吸收精细结构（EXAFS）部分，已在金和铂的L边同时测量。前驱体的XANES光谱提供了还原过程的实时信息，而EXAFS光谱揭示了生长中间阶段形成的团簇结构。对形成过程的这种洞察揭示了如何利用两种前驱体还原电位的差异，通过一锅合成法获得双金属合金的核壳型结构。纳米颗粒的核壳型结构也通过对完全形成的纳米颗粒进行原位离子蚀刻后的非原位能量色散光谱线扫描和X射线光电子能谱测量得到了证实。
