Zhai Peng, Shi Yifeng, Wang Qiuxiang, Xia Younan, Ding Kunlun
Department of Chemical Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
Nanoscale. 2021 Nov 18;13(44):18498-18506. doi: 10.1039/d1nr05636k.
The catalytic behaviors or properties of bimetallic catalysts are highly dependent on the surface composition, but it has been a grand challenge to acquire such information. In this work, we employ Pd@Pt core-shell nanocrystals with an octahedral shape and tunable Pt shell thickness as a model system to elucidate their surface compositions using catalytic reactions based upon the selective hydrogenation of butadiene and acetylene. Our results indicate that the surface of the core-shell nanocrystals changed from Pt-rich to Pd-rich when they were subjected to calcination under oxygen, a critical step involved in the preparation of many industrial catalysts. The inside-out migration can be attributed to both atomic interdiffusion and the oxidation of Pd atoms during the calcination process. The changes in surface composition were further confirmed using infrared and X-ray photoelectron spectroscopy. This work offers insightful guidance for the development and optimization of bimetallic catalysts toward various reactions.
双金属催化剂的催化行为或性质高度依赖于表面组成，但获取此类信息一直是一项巨大的挑战。在这项工作中，我们使用具有八面体形状且铂壳厚度可调的钯@铂核壳纳米晶体作为模型系统，通过基于丁二烯和乙炔选择性加氢的催化反应来阐明其表面组成。我们的结果表明，当核壳纳米晶体在氧气中煅烧时，其表面从富铂变为富钯，这是许多工业催化剂制备过程中的关键步骤。这种由内向外的迁移可归因于煅烧过程中的原子相互扩散和钯原子的氧化。表面组成的变化通过红外光谱和X射线光电子能谱进一步得到证实。这项工作为双金属催化剂针对各种反应的开发和优化提供了有见地的指导。
