Han Shaobo, Cai Chao, Xia Guang-Jie, Sun Congli, Shi Xiaobo, Zhou Weidong, Li Jun, Wang Yang-Gang, Gu Meng
State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China.
State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China.
Inorg Chem. 2020 Oct 5;59(19):14415-14423. doi: 10.1021/acs.inorgchem.0c02209. Epub 2020 Sep 18.
The hexagonal 4H phase gold nanostructures shows great potential for catalysis, optical, and biomedical fields. However, its phase stability remains largely unclear. Here, we report the 4H-to-face-centered cubic () phase transformation of gold induced by CO gas interactions and an electron beam observed through transmission electron microscopy ( TEM). The atomic scale transformation mechanism is revealed experimentally and supported by first-principle calculations. Density functional theory calculations show that the 4H-to- phase transformation processes via the transition of layer sliding with expanded layer spacing, which can be facilitated by both the adsorbed CO molecules and the extra electron provided by the electron beam. The transformation first takes place at the edges of the nanorods with the collective assistance of both CO and extra electrons, and then the inner portion of the bulk crystal follows with extra electrons as the lubricant. These results promote the understanding of the toxic effect of CO gas and shining light on the structural conversion and atomic migration of noble metal catalysts when they interact with CO molecules.
六方4H相金纳米结构在催化、光学和生物医学领域显示出巨大潜力。然而，其相稳定性在很大程度上仍不清楚。在此，我们报告了通过透射电子显微镜（TEM）观察到的由CO气体相互作用和电子束诱导的金的4H相向面心立方（）相转变。实验揭示了原子尺度的转变机制，并得到了第一性原理计算的支持。密度泛函理论计算表明，4H相向相的转变过程是通过层间距扩大的层滑动转变实现的，吸附的CO分子和电子束提供的额外电子都可以促进这一过程。转变首先在纳米棒的边缘在CO和额外电子的共同作用下发生，然后块状晶体的内部在额外电子作为润滑剂的情况下随之转变。这些结果促进了对CO气体和光照在贵金属催化剂与CO分子相互作用时对其结构转变和原子迁移的毒性作用的理解。
