Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA.
The NUANCE Center, Northwestern University, Evanston, IL, 60208, USA.
Nat Commun. 2023 Jun 24;14(1):3790. doi: 10.1038/s41467-023-39458-6.
Nanoparticles with high-index facets are intriguing because such facets can lend the structure useful functionality, including enhanced catalytic performance and wide-ranging optical tunability. Ligand-free solid-state syntheses of high index-facet nanoparticles, through an alloying-dealloying process with foreign volatile metals, are attractive owing to their materials generality and high yields. However, the role of foreign atoms in stabilizing the high-index facets and the dynamic nature of the transformation including the coarsening and facet regulation process are still poorly understood. Herein, the transformation of Pt salts to spherical seeds and then to tetrahexahedra, is studied in situ via gas-cell transmission electron microscopy. The dynamic behaviors of the alloying and dealloying process, which involves the coarsening of nanoparticles and consequent facet regulation stage are captured in the real time with a nanoscale spatial resolution. Based on additional direct evidence obtained using atom probe tomography and density functional theory calculations, the underlying mechanisms of the alloying-dealloying process are uncovered, which will facilitate broader explorations of high-index facet nanoparticle synthesis.
具有高指数晶面的纳米粒子很有趣，因为这些晶面可以赋予结构有用的功能，包括增强的催化性能和广泛的光学可调谐性。通过与挥发性外来金属的合金-脱合金过程，无配体的固态合成高指数晶面纳米粒子，由于其材料通用性和高收率而具有吸引力。然而，外来原子在稳定高指数晶面以及包括粗化和晶面调节过程在内的动态转变中的作用仍未得到很好的理解。在此，通过气体室透射电子显微镜原位研究了 Pt 盐向球形种子再到四面体的转变。使用原子探针断层扫描和密度泛函理论计算获得了额外的直接证据，揭示了合金-脱合金过程的潜在机制，这将有助于更广泛地探索高指数晶面纳米粒子的合成。
