Liu Maochang, Zhou Siyu, Choi Sang-Il, Xia Younan
The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332, United States.
International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow, Xi'an Jiaotong University, Xi'an, Shanxi 710049, P. R. China.
Precis Chem. 2023 Jul 24;1(6):372-381. doi: 10.1021/prechem.3c00060. eCollection 2023 Aug 28.
Noble-metal nanocrystals enclosed by high-index facets are of growing interest due to their enhanced catalytic performance in a variety of reactions. Herein, we report the deterministic synthesis of Pd nanocrystals encased by high-index facets by controlling the rate of deposition () relative to that of surface diffusion (). For octahedral seeds with truncated corners, a reduction rate (and thus deposition rate) faster than that of surface diffusion (i.e., > 1) led to the formation of concave trisoctahedra (TOH) with high-index facets. When the reduction was slowed down, in contrast, surface diffusion dominated the growth pathway. In the case of ≈ 1, truncated octahedra with enlarged sizes were produced. When the reduction rate was between these two extremes, we obtained concave tetrahexahedra (THH) without or with truncation. Similar growth patterns were also observed for the cuboctahedral seeds. When the Pd octahedra, concave TOH, and concave THH were tested for electrocatalyzing the formic acid oxidation (FAO) reaction, those with high-index facets were advantageous over the conventional Pd octahedra enclosed by {111} facets. This work not only contributes to the understanding of surface diffusion and its role in nanocrystal growth but also offers a general protocol for the synthesis of nanocrystals enclosed by high-index facets.
由于其在各种反应中具有增强的催化性能，被高指数晶面包围的贵金属纳米晶体越来越受到关注。在此，我们报告了通过控制沉积速率（）相对于表面扩散速率（），确定性地合成被高指数晶面包围的钯纳米晶体。对于具有截角的八面体晶种，还原速率（进而沉积速率）快于表面扩散速率（即>1）会导致形成具有高指数晶面的凹面三八面体（TOH）。相反，当还原速率减慢时，表面扩散主导生长路径。在≈1的情况下，会生成尺寸增大的截角八面体。当还原速率处于这两个极端之间时，我们获得了无截角或有截角的凹面四六面体（THH）。对于立方八面体晶种也观察到了类似的生长模式。当测试钯八面体、凹面TOH和凹面THH对甲酸氧化（FAO）反应的电催化性能时，具有高指数晶面的那些比由{111}面包围的传统钯八面体更具优势。这项工作不仅有助于理解表面扩散及其在纳米晶体生长中的作用，还提供了一种合成被高指数晶面包围的纳米晶体的通用方法。
