Seed-mediated growth is the most general way to controllably synthesize bimetal nano-heterostructures. Despite successful instances through trial and error were reported, the way for second metal depositing on the seed, namely whether the symmetry of resulted nano-heterostructure follows the original crystal symmetry of seed metal, remains an unpredictable issue to date. In this work, we propose that the thermodynamic factor, i.e., the difference of equilibrium electrochemical potentials (corresponding to their Fermi levels) of two metals in the growth solution, plays a key role for the symmetry breaking of bimetal nano-heterostructures during the seed-mediated growth. As a proof-of-principle experiment, by reversing the relative position of Fermi levels of the Pd nanocube seeds and the second metal Au with changing the concentration of reductant (L-ascorbic acid) in the growth solution, the structure of as-prepared products successfully evolved from centrosymmetric [email protected] core-shell trisoctahedra to asymmetric Pd-Au hetero-dimers. The idea was further demonstrated by the growth of Ag on the Pd seeds. The present work intends to reveal the origin of symmetry breaking in the seed-mediated growth of nano-heterostructures from the viewpoint of thermodynamics, and these new insights will in turn help to achieve rational construction of bimetal nano-heterostructures with specific functions.

种子介导的生长是可控合成双金属纳米异质结构的最常用方法。尽管通过反复试验报告了成功的实例，但第二种金属在晶种上沉积的方式，即所得纳米异质结构的对称性是否遵循晶种金属的原始晶体对称性，迄今为止仍然是一个不可预测的问题。在这项工作中，我们提出热力学因素，即生长溶液中两种金属的平衡电化学势（对应于它们的费米能级）的差异，对种子过程中双金属纳米异质结构的对称性破坏起着关键作用-介导的增长。作为原理验证实验，通过改变生长溶液中还原剂（L-抗坏血酸）的浓度，逆转 Pd 纳米立方体种子和第二金属 Au 的费米能​​级的相对位置，所制备产品的结构成功地从中心对称进化而来 [电子邮件保护]核壳三八面体到不对称的 Pd-Au 异二聚体。Ag 在 Pd 种子上的生长进一步证明了这一想法。目前的工作旨在从热力学的角度揭示种子介导的纳米异质结构生长中对称性破缺的起源，这些新见解反过来将有助于实现具有特定功能的双金属纳米异质结构的合理构建。所制备产品的结构成功地从中心对称 [电子邮件保护] 核壳三八面体演变为不对称 Pd-Au 异质二聚体。Ag 在 Pd 种子上的生长进一步证明了这一想法。目前的工作旨在从热力学的角度揭示种子介导的纳米异质结构生长中对称性破缺的起源，这些新见解反过来将有助于实现具有特定功能的双金属纳米异质结构的合理构建。所制备产品的结构成功地从中心对称 [电子邮件保护] 核壳三八面体演变为不对称 Pd-Au 异质二聚体。Ag 在 Pd 种子上的生长进一步证明了这一想法。目前的工作旨在从热力学的角度揭示种子介导的纳米异质结构生长中对称性破缺的起源，这些新见解反过来将有助于实现具有特定功能的双金属纳米异质结构的合理构建。