Origin of symmetry breaking in the seed-mediated growth of bi-metal nano-heterostructures

作     者：Guifen Du Jun Pei Zhiyuan Jiang Qiaoli Chen Zhenming Cao Qin Kuang Zhaoxiong Xie Lansun Zheng 

作者机构：State Key Laboratory of Physical Chemistry of Solid SurfacesCollaborative Innovation Center of Chemistry for Energy MaterialsDepartment of ChemistryCollege of Chemistry and Chemical EngineeringXiamen University Pen-Tung Sah Institute of Micro-Nano Science and TechnologyXiamen University 

出 版 物：《Science Bulletin》 (科学通报（英文版）)

年 卷 期：2018年第63卷第14期

页      面：892-899页

核心收录：

学科分类：07[理学] 070205[理学-凝聚态物理] 0702[理学-物理学] 

基　　金：supported by the National Basic Research Program of China(2015CB93230) the National Key Research and Development Program of China(2017YFA0206801) the National Natural Science Foundation of China(21333008,21671163,21721001,and 21773190) the Fundamental Research Funds for the Central Universities(20720160026) 

主　　题：中心对称 金属片 生长期 膨胀率 种子 起源 电气化学 相对位置 

摘      要：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 Pd@Au 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.