posted on 2023-11-28, 15:44authored byFan Xue, Qiang Li, Mingxin Lv, Yuanfei Song, Tianxing Yang, Xiaoge Wang, Tianyi Li, Yang Ren, Koji Ohara, Yufei He, Dianqing Li, Qiheng Li, Xin Chen, Kun Lin, Xianran Xing
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 (Pdsph) 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 Pdsph was revealed. Density functional
theory calculations verified the obvious weakening of the ethylene
adsorption energy on account of the surface strain of Pdsph. 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.