Abstract
Most of the world’s hydrogen supply is currently obtained by reforming hydrocarbons. ‘Reformate’ hydrogen contains significant quantities of CO that poison current hydrogen fuel-cell devices. Catalysts are needed to remove CO from hydrogen through selective oxidation. Here, we report first-principles-guided synthesis of a nanoparticle catalyst comprising a Ru core covered with an approximately 1–2-monolayer-thick shell of Pt atoms. The distinct catalytic properties of these well-characterized core–shell nanoparticles were demonstrated for preferential CO oxidation in hydrogen feeds and subsequent hydrogen light-off. For H2 streams containing 1,000 p.p.m. CO, H2 light-off is complete by 30 ∘C, which is significantly better than for traditional PtRu nano-alloys (85 ∘C), monometallic mixtures of nanoparticles (93 ∘C) and pure Pt particles (170 ∘C). Density functional theory studies suggest that the enhanced catalytic activity for the core–shell nanoparticle originates from a combination of an increased availability of CO-free Pt surface sites on the Ru@Pt nanoparticles and a hydrogen-mediated low-temperature CO oxidation process that is clearly distinct from the traditional bifunctional CO oxidation mechanism.
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Acknowledgements
Work at Maryland was supported by the National Science Foundation under Grant No. 0401850, the University of Maryland Energy Research Center (UMERC). Work at UW-Madison was supported by DOE-BES, Chemical Sciences Division (DE-FG02-05ER15731 and DE-FG02-03ER15468), and S.C. Johnson. Supercomputing time at DOE-NERSC, PNNL and ORNL facilities is greatly appreciated. A.U.N. thanks L. Grabow for his valuable help.
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Alayoglu, S., Nilekar, A., Mavrikakis, M. et al. Ru–Pt core–shell nanoparticles for preferential oxidation of carbon monoxide in hydrogen. Nature Mater 7, 333–338 (2008). https://doi.org/10.1038/nmat2156
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DOI: https://doi.org/10.1038/nmat2156
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