Xue Fan, Li Qiang, Lv Mingxin, Song Yuanfei, Yang Tianxing, Wang Xiaoge, Li Tianyi, Ren Yang, Ohara Koji, He Yufei, Li Dianqing, Li Qiheng, Chen Xin, Lin Kun, Xing Xianran
Beijing Advanced Innovation Center for Materials Genome Engineering, Institute of Solid State Chemistry, University of Science and Technology Beijing, Beijing 100083, China.
State Key Laboratory of Chemical Resource Engineering, Beijing Engineering Center for Hierarchical Catalysts Beijing University of Chemical Technology, Beijing 100029, China.
J Am Chem Soc. 2023 Dec 13;145(49):26728-26735. doi: 10.1021/jacs.3c08619. Epub 2023 Nov 28.
Deciphering the three-dimensional (3D) insight into nanocatalyst surfaces at the atomic level is crucial to understanding catalytic reaction mechanisms and developing high-performance catalysts. Nevertheless, better understanding the inherent insufficiency of a long-range ordered lattice in nanocatalysts is a big challenge. In this work, we report the local structure of Pd nanocatalysts, which is beneficial for demonstrating the shape-structure-adsorption relationship in acetylene hydrogenation. The 5.27 nm spherical Pd catalyst (Pd) shows an ethylene selectivity of 88% at complete acetylene conversion, which is much higher than those of the Pd octahedron and Pd cube and superior to other reported monometallic Pd nanocatalysts so far. By virtue of the local structure revelation combined with the atomic pair distribution function (PDF) and reverse Monte Carlo (RMC) simulation, the atomic surface distribution of the unique compressed strain of Pd-Pd pairs in Pd was revealed. Density functional theory calculations verified the obvious weakening of the ethylene adsorption energy on account of the surface strain of Pd. It is the main factor to avoid the over-hydrogenation of acetylene. The present work, entailing shape-induced surface strain manipulation and atomic 3D insight, opens a new path to understand and optimize chemical activity and selectivity in the heterogeneous catalysis process.
在原子水平上解析纳米催化剂表面的三维（3D）见解对于理解催化反应机理和开发高性能催化剂至关重要。然而，更好地理解纳米催化剂中长程有序晶格的固有不足是一项巨大挑战。在这项工作中，我们报道了钯纳米催化剂的局部结构，这有利于阐明乙炔加氢中的形状-结构-吸附关系。5.27纳米的球形钯催化剂（Pd）在乙炔完全转化时显示出88%的乙烯选择性，这远高于钯八面体和钯立方体的选择性，并且优于目前报道的其他单金属钯纳米催化剂。借助结合原子对分布函数（PDF）和反向蒙特卡罗（RMC）模拟的局部结构揭示，揭示了钯中钯-钯对独特压缩应变的原子表面分布。密度泛函理论计算证实，由于钯的表面应变，乙烯吸附能明显减弱。这是避免乙炔过度加氢的主要因素。目前这项涉及形状诱导表面应变调控和原子三维见解的工作，为理解和优化多相催化过程中的化学活性和选择性开辟了一条新途径。
