Catalytic performance of Ru, Os, and Rh nanoparticles for ammonia synthesis: A density functional theory analysis

Atsushi Ishikawa, Toshiki Doi, Hiromi Nakai

    Research output: Contribution to journalArticle

    20 Citations (Scopus)

    Abstract

    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.

    Original languageEnglish
    Pages (from-to)213-222
    Number of pages10
    JournalJournal of Catalysis
    Volume357
    DOIs
    Publication statusPublished - 2018 Jan 1

    Keywords

    • Density functional theory
    • Kinetic analysis
    • NH synthesis
    • Particle size dependence
    • Transition metal

    ASJC Scopus subject areas

    • Catalysis
    • Physical and Theoretical Chemistry

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