Catalytic performance of Ru, Os, and Rh nanoparticles for ammonia synthesis: A density functional theory analysis
Catalytic performance of Ru, Os, and Rh nanoparticles for ammonia synthesis: A density functional theory analysis
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DOI：
10.1016/j.jcat.2017.11.018
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发表时间：
2018-01-01
影响因子：
7.3
通讯作者：
Nakai, Hiromi
中科院分区：
文献类型：
--
作者：
Ishikawa, Atsushi;Doi, Toshiki;Nakai, Hiromi
用密度泛函理论方法研究了Ru、Os和Rh纳米粒子催化剂上NH3的合成。Ru和Os纳米粒子的形状相似，而Rh的形状明显不同。对于所有金属物种，台阶位置出现在纳米颗粒直径(D)>；2-4 nm。计算的活化势垒(E-a)在台阶位置较小，而Ru和Os的台阶位置具有相似的E-a值，尽管前者具有较高的转换频率。这可能是由于Ru上空置场地的地表覆盖率较高。虽然在d=2-4 nm处NH3合成速率的增加与Ru、Os和Rh相同，但反应速率按Ru&Gt；Os&Gt；Rh的顺序递减。结果表明，E-a值、表面空位和台阶点数是影响NH3合成的重要因素。由于满足所有这三个因素，Ru纳米颗粒表现出高活性。(C)2017 Elsevier Inc.保留所有权利。
NH3 synthesis on Ru, Os, and Rh nanoparticle catalysts was investigated using density functional theory calculations. The Ru and Os nanoparticles exhibited similar shapes, while that of Rh differed significantly. For all metal species, step sites appeared at nanoparticle diameters (d) >2-4 nm. The calculated activation barriers (E-a) were small at step sites, and Ru and Os step sites exhibited similar E-a values despite the former having a higher turnover frequency. This is likely due to the surface coverage of vacant sites being higher on Ru. Although the increase in NH3 synthesis rate at d = 2-4 nm was common to Ru, Os, and Rh, the reaction rates decreased in the order: Ru > Os > Rh. Our results show that E-a values, surface vacant sites, and the number of step sites are important factors for NH3 synthesis. The Ru nanoparticles exhibited high activity due to satisfying all three factors. (C) 2017 Elsevier Inc. All rights reserved.