Report

Interfacial Effects in Iron-Nickel Hydroxide–Platinum Nanoparticles Enhance Catalytic Oxidation

Science  02 May 2014:
Vol. 344, Issue 6183, pp. 495-499
DOI: 10.1126/science.1252553

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Improving Reactions at Interfaces

Alloying precious metals such as platinum with more abundant transition metals, such as iron and nickel, can both improve their catalytic reactivity and lower catalyst cost. Chen et al. (p. 495) explored using coatings of iron oxide–hydroxide layers on supported platinum nanoparticles for CO oxidation. The presence of this layer allowed the reaction to run rapidly at room temperature by bringing together different reaction sites on the two metals. The addition of nickel improved catalyst lifetime, and an oxidative transformation created a more complex nanoparticle morphology that increased platinum utilization.

Abstract

Hybrid metal nanoparticles can allow separate reaction steps to occur in close proximity at different metal sites and accelerate catalysis. We synthesized iron-nickel hydroxide–platinum (transition metal-OH-Pt) nanoparticles with diameters below 5 nanometers and showed that they are highly efficient for carbon monoxide (CO) oxidation catalysis at room temperature. We characterized the composition and structure of the transition metal–OH-Pt interface and showed that Ni2+ plays a key role in stabilizing the interface against dehydration. Density functional theory and isotope-labeling experiments revealed that the OH groups at the Fe3+-OH-Pt interfaces readily react with CO adsorbed nearby to directly yield carbon dioxide (CO2) and simultaneously produce coordinatively unsaturated Fe sites for O2 activation. The oxide-supported PtFeNi nanocatalyst rapidly and fully removed CO from humid air without decay in activity for 1 month.

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