美国佐治亚理工学院Younan Xia团队报道了不同形貌铑纳米晶的动力学控制合成及其热性能和催化性能的比较研究。 相关研究成果于2021年4月14日发表在国际顶尖学术期刊《美国化学会杂志》。

研究人员报道了通过控制预生成的Rh立方晶种的生长动力学来合成了具有不同形貌的Rh纳米晶体。具体而言，在适当的前驱体还原动力学下，可以从相同的立方晶种中获得立方、立方八面体和八面体形状的Rh纳米晶。其成功合成还依赖于使用无卤化物前体来避免氧化蚀刻，以及足够高的温度来去除种子中的Br-离子，同时确保充分的表面扩散。具有立方体和八面体形貌的Rh纳米晶体的成功合成使得评估热和催化性能的晶面依赖性成为了可能。

原位电子显微镜研究结果表明，立方和八面体Rh纳米晶在700℃和500℃下都能保持其原始形状。当作为肼分解的催化剂进行测试时，八面体纳米晶相对于立方纳米晶对于氢气的选择性提高了4背。至于乙醇氧化，顺序相反，立方纳米晶体的活性是八面体样品的三倍左右。

附：英文原文

Title: Kinetically Controlled Synthesis of Rhodium Nanocrystals with Different Shapes and a Comparison Study of Their Thermal and Catalytic Properties

Author: Ming Zhao, Zitao Chen, Yifeng Shi, Zachary D. Hood, Zhiheng Lyu, Minghao Xie, Miaofang Chi, Younan Xia

Issue&Volume: April 14, 2021

Abstract: We report the synthesis of Rh nanocrystals with different shapes by controlling the kinetics involved in the growth of preformed Rh cubic seeds. Specifically, Rh nanocrystals with cubic, cuboctahedral, and octahedral shapes can all be obtained from the same cubic seeds under suitable reduction kinetics for the precursor. The success of such a synthesis also relies on the use of a halide-free precursor to avoid oxidative etching, as well as the involvement of a sufficiently high temperature to remove Br– ions from the seeds while ensuring adequate surface diffusion. The availability of Rh nanocrystals with cubic and octahedral shapes allows for an evaluation of the facet dependences of their thermal and catalytic properties. The data from in situ electron microscopy studies indicate that the cubic and octahedral Rh nanocrystals can keep their original shapes up to 700 and 500 °C, respectively. When tested as catalysts for hydrazine decomposition, the octahedral nanocrystals exhibit almost 4-fold enhancement in terms of H2 selectivity relative to the cubic counterpart. As for ethanol oxidation, the order is reversed, with the cubic nanocrystals being about three times more active than the octahedral sample.

DOI: 10.1021/jacs.1c02734

Source: https://pubs.acs.org/doi/10.1021/jacs.1c02734