Quantitative 3D evolution of colloidal nanoparticle oxidation in solution
Quantitative 3D evolution of colloidal nanoparticle oxidation in solution
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DOI：
10.1126/science.aaf6792
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发表时间：
2017-04-21
期刊：
影响因子：
56.9
通讯作者：
Kamath, Ganesh
中科院分区：
文献类型：
--
作者：
Sun, Yugang;Zuo, Xiaobing;Kamath, Ganesh
实时跟踪溶液中胶体纳米颗粒的三维（3D）演化对于理解纳米颗粒生长和转化的复杂机制至关重要。我们同时使用时间分辨的小角和广角x射线散射来监测高度均匀的胶体铁纳米颗粒的氧化，从而能够以类似于5埃的空间分辨率重建纳米颗粒的中间三维形态。现场观察与大规模反应分子动力学模拟相结合，揭示了通过纳米级Kirkendall过程从固体金属纳米颗粒转变为空心金属氧化物纳米壳的细节，例如，随着它们的生长，空洞的聚并以及依赖于结晶度的质量扩散方向的逆转。我们的研究结果强调了缺陷化学和缺陷动力学在决定纳米颗粒转化和形成方面的复杂相互作用。
Real-time tracking of the three-dimensional (3D) evolution of colloidal nanoparticles in solution is essential for understanding complex mechanisms involved in nanoparticle growth and transformation. We used time-resolved small-angle and wide-angle x-ray scattering simultaneously to monitor oxidation of highly uniform colloidal iron nanoparticles, enabling the reconstruction of intermediate 3D morphologies of the nanoparticles with a spatial resolution of similar to 5 angstroms. The in situ observations, combined with large-scale reactive molecular dynamics simulations, reveal the details of the transformation from solid metal nanoparticles to hollow metal oxide nanoshells via a nanoscale Kirkendall process-for example, coalescence of voids as they grow and reversal of mass diffusion direction depending on crystallinity. Our results highlight the complex interplay between defect chemistry and defect dynamics in determining nanoparticle transformation and formation.