TY - JOUR
T1 - Catalytic performance of Ru, Os, and Rh nanoparticles for ammonia synthesis
T2 - A density functional theory analysis
AU - Ishikawa, Atsushi
AU - Doi, Toshiki
AU - Nakai, Hiromi
N1 - Funding Information:
This study was supported in part by the Core Research for Evolutional Science and Technology (CREST) program from the Japan Science and Technology (JST) Agency, in addition to Grants-in-Aid for Challenging and Exploratory Research ‘‘KAKENHI 16K17860” from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan.
Publisher Copyright:
© 2017 Elsevier Inc.
PY - 2018/1
Y1 - 2018/1
N2 - 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 (Ea) were small at step sites, and Ru and Os step sites exhibited similar Ea 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 Ea 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.
AB - 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 (Ea) were small at step sites, and Ru and Os step sites exhibited similar Ea 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 Ea 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.
KW - Density functional theory
KW - Kinetic analysis
KW - NH synthesis
KW - Particle size dependence
KW - Transition metal
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U2 - 10.1016/j.jcat.2017.11.018
DO - 10.1016/j.jcat.2017.11.018
M3 - Article
AN - SCOPUS:85037062800
SN - 0021-9517
VL - 357
SP - 213
EP - 222
JO - Journal of Catalysis
JF - Journal of Catalysis
ER -