Bimetallic Au@Cu core–shell nanocrystals have been synthesized by a two-step seed-mediated growth method through controlled heteroepitaxial growth of Cu shells on Au nanorods serving as seeds. The final crystal structures have cubic morphology with edge lengths from 50 to 100 nm due to a strong affinity of hexadecylamine, which is a selective capping agent for the {100} facets of Cu. Various characterizations reveal that the epitaxial growth mechanism is based on block-type growth mode, rather than layer-by-layer growth mode, owing to the larger mismatch in the different lattice constants between Au core and Cu shell. Moreover, contrastive experiments using Au nanobipyramids as seeds were carried out to gain further insight into the heteroepitaxial growth mechanism. Combining first-principles density-functional theory with experimental results, the binding energies of Cu atoms at different sites on Au surfaces are explored to clarify the aspects of nanostructure formation. This study provides useful insights into the effective synthesis method and the further investigation of the proposed growth mechanism.

中文翻译：

---

简便合成和@铜Au中的异质外延生长机制的核心-壳通过第一原理研究探查双金属纳米立方体†

双金属Au @ Cu核壳纳米晶体是通过两步种子介导的生长方法，通过在用作种子的Au纳米棒上控制铜壳的异质外延生长而合成的。由于十六烷基胺的强亲和力，最终的晶体结构具有边长为50至100 nm的立方形态，十六烷基胺是Cu {100}晶面的选择性封端剂。各种特征表明，由于Au核与Cu壳之间的不同晶格常数存在较大的不匹配，因此外延生长机制基于块状生长模式，而不是逐层生长模式。此外，进行了使用金纳米双锥体作为种子的对比实验，以进一步了解异质外延生长机理。将第一原理密度泛函理论与实验结果相结合，探索了Au表面不同位置的Cu原子的结合能，以阐明纳米结构形成的各个方面。这项研究为有效的合成方法和拟议的生长机制的进一步研究提供了有益的见解。