发表机构
University of California Berkeley; Fudan University（加州大学伯克利分校; 复旦大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究报道双金属纳米颗粒可形成热力学控制的亚纳米“壳-二聚体”覆盖层结构，以Au-Rh为模型揭示其由表面、界面和应变能竞争稳定，受各向异性应变限制，为多金属表面结构调控提供基础。
AI 中文摘要
纳米颗粒的性质由其表面决定，但其原子尺度的表面结构仍难以预测。在此，我们报道双金属纳米颗粒可以形成一种热力学控制的“壳-二聚体”结构，其中一种金属在另一种金属上形成仅几个原子层厚的覆盖层。以Au-Rh为模型体系，原子分辨成像和分子动力学表明，在Rh上形成了超薄Au覆盖层，该覆盖层由表面能、界面能和应变能之间的竞争所稳定。各向异性应变将其生长限制在亚纳米尺度，表面化学性质的变化可使覆盖层完全失稳。在一系列双金属纳米颗粒中，我们发现覆盖层的形成与元素不混溶性和晶格失配相关。这些发现为理解和控制多金属纳米颗粒的表面结构提供了基础。
英文摘要
Nanoparticle properties are governed by their surfaces, yet their atomic-scale surface structures remain challenging to predict. Here, we report that bimetallic nanoparticles can form a thermodynamically controlled "shell-dimer" architecture in which one metal forms an overlayer only a few atomic layers thick on another. Using Au-Rh as a model system, atomic-resolution imaging and molecular dynamics show that an ultrathin Au overlayer forms on Rh, stabilized by competition among surface, interfacial, and strain energies. Anisotropic strain limits its growth to the subnanometer scale, and changes in surface chemistry can destabilize the overlayer altogether. Across a range of bimetallic nanoparticles, we found that overlayer formation is associated with elemental immiscibility and lattice mismatch. These findings provide a basis for understanding and controlling surface structures in multimetallic nanoparticles.
Commentsmain text: 18 pages, 5 figures; SI: 62 pages, 53 figures
