UV-induced Photoelectron Spectroscopy UVPS

Ru-based catalysts have been identified as highly active catalysts for ammonia synthesis [156]. The catalytic activity of an Ru-based catalyst can be improved by the addition of alkali or earth-alkali promoters [157, 158]. Many kinetic and theoretic studies have been carried out in order to understand the role of these promoters in ammonia synthesis. Guraya et al. [159] investigated the alkali- and earth-alkali-promoted ruthenium eatalysts supported on graphitized carbon by 

Pt-based electrocatalysts in fuel cells are severely poisoned by the CO intermediate, which is strongly adsorbed on the Pt surface and considerably reduces its electroactivity. It has been widely accepted that the addition of Ru to Pt-based catalysts can promote CO removal by the so-called bifunctional mechanism [160, 161]. However, recent theoretical and experimental studies suggest that Mo-Pt combinations could be not only much cheaper but even more efficient catalysts for CO oxidation than Ru-Pt [162, 163]. To explore more effective metal promoters for CO removal, a fundamental understanding of the adsorption of CO on the metal promoter is very important. UVPS is a powerful surface analysis tool in adsorption studies. It can tell whether the adsorbate species on a solid surface is associative or dissociative, because the contributions of the two species to the valence electronic stracture should be quite different. 

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