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Self-assembly of noble metal monolayers on transition metal carbide nanoparticle catalysts

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Science  20 May 2016:
Vol. 352, Issue 6288, pp. 974-978
DOI: 10.1126/science.aad8471

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Tough core-shell catalysts

One approach for increasing the activity of precious metals in catalysis is to coat them onto less expensive earth-abundant transition metal cores such as nickel, but often these structures alloy and deactivate during reactions. Hunt et al. synthesized several types of transition metal carbide nanoparticles coated with atomically thin precious-metal shells. Titanium-doped tungsten carbide nanoparticles with platinum-ruthenium shells were highly active for methanol electrooxidation, stable over 10,000 cycles, and resistant to CO deactivation.

Science, this issue p. 974

Abstract

We demonstrated the self-assembly of transition metal carbide nanoparticles coated with atomically thin noble metal monolayers by carburizing mixtures of noble metal salts and transition metal oxides encapsulated in removable silica templates. This approach allows for control of the final core-shell architecture, including particle size, monolayer coverage, and heterometallic composition. Carbon-supported Ti0.1W0.9C nanoparticles coated with Pt or bimetallic PtRu monolayers exhibited enhanced resistance to sintering and CO poisoning, achieving an order of magnitude increase in specific activity over commercial catalysts for methanol electrooxidation after 10,000 cycles. These core-shell materials provide a new direction to reduce the loading, enhance the activity, and increase the stability of noble metal catalysts.

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