Perxés Perich Marta, O'Connor Christopher R, Draijer Koen M, Visser Nienke L, Artrith Nongnuch, Reece Christian, de Jongh Petra E, van der Hoeven Jessi E S
Materials Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University 3584 CG Utrecht The Netherlands
Rowland Institute at Harvard, Harvard University Cambridge Massachusetts 02142 USA.
J Mater Chem A Mater. 2024 Jun 27;12(47):32760-32774. doi: 10.1039/d4ta03030c. eCollection 2024 Dec 9.
The catalytic and plasmonic properties of bimetallic gold-palladium (Au-Pd) nanoparticles (NPs) critically depend on the distribution of the Au and Pd atoms inside the nanoparticle bulk and at the surface. Under operating conditions, the atomic distribution is highly dynamic. Analyzing gas induced redistribution kinetics at operating temperatures is therefore key in designing and understanding the behavior of Au-Pd nanoparticles for applications in thermal and light-driven catalysis, but requires advanced characterization strategies. In this work, we achieve the analysis of the gas dependent alloying kinetics in bimetallic Au-Pd nanoparticles at elevated temperatures through a combination of CO-DRIFTS and gas-phase transmission electron microscopy (TEM), providing direct insight in both the surface- and nanoparticle bulk redistribution dynamics. Specifically, we employ a well-defined model system consisting of colloidal Au-core Pd-shell NPs, monodisperse in size and uniform in composition, and quantify the alloying dynamics of these NPs in H and O under isothermal conditions. By extracting the alloying kinetics from TEM measurements, we show that the alloying behavior in Au-Pd NPs can be described by a numerical diffusion model based on Fick's second law. Overall, our results indicate that exposure to reactive gasses strongly affects the surface composition and surface alloying kinetics, but has a smaller effect on the alloying dynamics of the nanoparticle bulk. Both our methodology as well as the quantitative insights on restructuring phenomena can be extended to a wider range of bimetallic nanoparticle systems and are relevant in understanding the behavior of nanoparticle catalysts under operating conditions.
双金属金钯（Au-Pd）纳米颗粒（NPs）的催化和等离子体特性关键取决于金和钯原子在纳米颗粒内部及表面的分布。在工作条件下，原子分布具有高度动态性。因此，分析工作温度下气体诱导的再分布动力学是设计和理解用于热催化和光驱动催化的Au-Pd纳米颗粒行为的关键，但这需要先进的表征策略。在这项工作中，我们通过结合CO-DRIFTS和气相透射电子显微镜（TEM），实现了对高温下双金属Au-Pd纳米颗粒中气体依赖的合金化动力学的分析，从而直接洞察表面和纳米颗粒内部的再分布动力学。具体而言，我们采用了一个明确的模型系统，该系统由尺寸单分散且组成均匀的胶体Au核Pd壳NPs组成，并在等温条件下量化了这些NPs在H和O中的合金化动力学。通过从TEM测量中提取合金化动力学，我们表明Au-Pd NPs中的合金化行为可以用基于菲克第二定律的数值扩散模型来描述。总体而言，我们的结果表明，暴露于反应性气体强烈影响表面组成和表面合金化动力学，但对纳米颗粒内部的合金化动力学影响较小。我们的方法以及对重组现象的定量见解都可以扩展到更广泛的双金属纳米颗粒系统，并且对于理解纳米颗粒催化剂在工作条件下的行为具有重要意义。
