Xia Yu, Nelli Diana, Ferrando Riccardo, Yuan Jun, Li Z Y
School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, UK.
Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, China.
Nat Commun. 2021 May 21;12(1):3019. doi: 10.1038/s41467-021-23305-7.
Controlled growth of far-from-equilibrium-shaped nanoparticles with size selection is essential for the exploration of their unique physical and chemical properties. Shape control by wet-chemistry preparation methods produces surfactant-covered surfaces with limited understanding due to the complexity of the processes involved. Here, we report the controlled production and transformation of octahedra to tetrahedra of size-selected platinum nanocrystals with clean surfaces in an inert gas environment. Molecular dynamics simulations of the growth reveal the key symmetry-breaking atomic mechanism for this autocatalytic shape transformation, confirming the experimental conditions required. In-situ heating experiments demonstrate the relative stability of both octahedral and tetrahedral Pt nanocrystals at least up to 700 °C and that the extended surface diffusion at higher temperature transforms the nanocrystals into equilibrium shape.
对具有尺寸选择性的远离平衡形状纳米颗粒进行可控生长，对于探索其独特的物理和化学性质至关重要。由于湿法化学制备方法所涉及过程的复杂性，通过这些方法进行形状控制会产生表面覆盖有表面活性剂的情况，对此的了解有限。在此，我们报告了在惰性气体环境中，对具有清洁表面的尺寸选择性铂纳米晶体从八面体到四面体的可控制备和转变。生长过程的分子动力学模拟揭示了这种自催化形状转变的关键对称性破缺原子机制，证实了所需的实验条件。原位加热实验表明，八面体和四面体铂纳米晶体至少在高达700°C时都具有相对稳定性，并且在较高温度下扩展的表面扩散会使纳米晶体转变为平衡形状。
