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Journal Article | FZJ-2014-06487 |
; ; ; ;
2014
American Chemical Society
Washington, DC
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Please use a persistent id in citations: doi:10.1021/ja4124658
Abstract: Colloid-based chemical synthesis methodsof bimetallic alloy nanoparticles (NPs) provide goodmonodispersity, yet generally show a strong variation ofthe resulting mean particle size with alloy composition.This severely compromises accurate correlation betweencomposition of alloy particles and their size-dependentproperties. To address this issue, a general CO adsorptionassistedcapping ligand-free solvothermal synthesis methodis reported which provides homogeneous bimetallic NPswith almost perfectly constant particle size over anunusually wide compositional range. Using Pt−Ni alloyNPs as an example, we show that variation of the reactiontemperature between 160 and 240 °C allows for precisecontrol of the resulting alloy particle bulk compositionbetween 15 and 70 atomic % Ni, coupled with a constantmean particle size of ∼4 nm. The size-confining and Nicontent-controlling role of CO during the nucleation andgrowth processes are investigated and discussed. Datasuggest that size-dependent CO surface chemisorption andreversible Ni-carbonyl formation are key factors for theachievement of a constant particle size and temperaturecontrolledNi content. To demonstrate the usefulness ofthe independent control of size and composition, sizedeconvolutedrelations between composition and electrocatalyticproperties are established. Refining earlier reports,we uncover intrinsic monotonic relations between catalyticactivity and initial Ni content, as expected from theoreticalconsiderations.
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