Yan Xue, Wang Xiangxiang, Han Jingli, Du Xiangjian, Liu Zhongyi, Yang Yongpeng
Henan Institute of Advanced Technology, Zhengzhou University, Zhengzhou 450003, China.
Henan Engineering Research Center of Catalysis and Separation of Cyclohexanol, School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450001, China.
Phys Chem Chem Phys. 2023 Apr 12;25(15):10405-10416. doi: 10.1039/d2cp05591k.
The reconstruction of bimetals under reaction conditions is critical for precisely controlling the catalytic performance of bimetallic catalysts. The surface diffusion mechanisms of Cu@Ag nanoparticles before and after CO adsorption were studied in this work. The diffusion patterns with the lowest energy barrier were determined by using molecular dynamics and meta-dynamics simulations. The effects of nanoparticle size, surface species and CO adsorption were taken into account. We present a mechanism of multiple atom collaborative diffusion during Cu@Ag bimetal reconstruction: surface atoms diffuse outward to form adatoms first, with nearby atoms occupying the original position of the outward diffused atom, and the outward diffusion can accelerate the inward diffusion of nearby surface atoms. The surface diffusion mechanisms of Cu@Ag under a CO atmosphere are different from those of Pd@Au that we previously presented, due to the different diffusion abilities of metal atoms. Our study provides a potential strategy to control the beginning of reconstruction to change the stability of bimetals under reaction conditions.
在反应条件下双金属的重构对于精确控制双金属催化剂的催化性能至关重要。本工作研究了CO吸附前后Cu@Ag纳米颗粒的表面扩散机制。通过分子动力学和元动力学模拟确定了具有最低能垒的扩散模式。考虑了纳米颗粒尺寸、表面物种和CO吸附的影响。我们提出了Cu@Ag双金属重构过程中多原子协同扩散的机制：表面原子首先向外扩散形成吸附原子，附近原子占据向外扩散原子的原始位置，向外扩散可加速附近表面原子的向内扩散。由于金属原子的扩散能力不同，CO气氛下Cu@Ag的表面扩散机制与我们之前提出的Pd@Au的不同。我们的研究提供了一种潜在策略，可控制重构的起始以改变反应条件下双金属的稳定性。
