Gamler Jocelyn T L, Leonardi Alberto, Sang Xiahan, Koczkur Kallum M, Unocic Raymond R, Engel Michael, Skrabalak Sara E
Department of Chemistry, Indiana University 800 East Kirkwood Avenue Bloomington Indiana 47405 USA
Institute for Multiscale Simulation, IZNF, Friedrich-Alexander University Erlangen-Nürnberg Cauerstrasse 3 91058 Erlangen Germany.
Nanoscale Adv. 2020 Mar 2;2(3):1105-1114. doi: 10.1039/d0na00061b. eCollection 2020 Mar 17.
Bimetallic nanocrystals with a core@shell architecture are versatile, multifunctional particles. The lattice mismatch between core and shell regions induces strain, affecting the electronic properties of the shell metal, which is important for applications in catalysis. Here, we analyze this strain in core@shell nanocubes as a function of lattice mismatch and shell thickness. Coupling geometric phase analysis from atomic resolution scanning transmission electron microscopy images with molecular dynamics simulations reveals lattice relaxation in the shell within only a few monolayers and an overexpansion in the axial direction. Interestingly, many works report core@shell metal nanocatalysts with optimum performance at greater shell thicknesses. Our findings suggest that not strain alone but secondary factors, such as structural defects or structural changes , may account for observed enhancements in some strain-engineered nanocatalysts; , Rh@Pt nanocubes for formic acid electrooxidation.
具有核壳结构的双金属纳米晶体是多功能的粒子。核区与壳区之间的晶格失配会产生应变，影响壳层金属的电子性质，这对于催化应用很重要。在这里，我们分析了核壳纳米立方体中的这种应变与晶格失配和壳层厚度的关系。将原子分辨率扫描透射电子显微镜图像的几何相位分析与分子动力学模拟相结合，揭示了仅在几个单分子层内壳层中的晶格弛豫以及轴向的过度膨胀。有趣的是，许多研究报告称，壳层厚度更大时核壳金属纳米催化剂具有最佳性能。我们的研究结果表明，并非仅应变，而是诸如结构缺陷或结构变化等次要因素，可能是某些应变工程纳米催化剂中观察到的性能增强的原因；例如，用于甲酸电氧化的Rh@Pt纳米立方体。
