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Title: One-Step Polyol Synthesis and Langmuir-Blodgett MonolayerFormation of Size-tunable Monodisperse Rhodium Nanocrystals withCatalytically Active (111) Surface Structure

Abstract

No abstract prepared.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE Director, Office of Science
OSTI Identifier:
929679
Report Number(s):
LBNL-63525
TRN: US200812%%712
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry C; Journal Volume: 111; Journal Issue: 33; Related Information: Journal Publication Date: 2007
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; RHODIUM; SYNTHESIS; CATALYTIC EFFECTS; SURFACE PROPERTIES; MORPHOLOGY

Citation Formats

Zhang, Y., Grass, M.E., Habas, S.E., Tao, F., Zhang, T., Yang,P., and Somorjai, G.A. One-Step Polyol Synthesis and Langmuir-Blodgett MonolayerFormation of Size-tunable Monodisperse Rhodium Nanocrystals withCatalytically Active (111) Surface Structure. United States: N. p., 2007. Web. doi:10.1021/jp073350h.
Zhang, Y., Grass, M.E., Habas, S.E., Tao, F., Zhang, T., Yang,P., & Somorjai, G.A. One-Step Polyol Synthesis and Langmuir-Blodgett MonolayerFormation of Size-tunable Monodisperse Rhodium Nanocrystals withCatalytically Active (111) Surface Structure. United States. doi:10.1021/jp073350h.
Zhang, Y., Grass, M.E., Habas, S.E., Tao, F., Zhang, T., Yang,P., and Somorjai, G.A. Tue . "One-Step Polyol Synthesis and Langmuir-Blodgett MonolayerFormation of Size-tunable Monodisperse Rhodium Nanocrystals withCatalytically Active (111) Surface Structure". United States. doi:10.1021/jp073350h.
@article{osti_929679,
title = {One-Step Polyol Synthesis and Langmuir-Blodgett MonolayerFormation of Size-tunable Monodisperse Rhodium Nanocrystals withCatalytically Active (111) Surface Structure},
author = {Zhang, Y. and Grass, M.E. and Habas, S.E. and Tao, F. and Zhang, T. and Yang,P. and Somorjai, G.A.},
abstractNote = {No abstract prepared.},
doi = {10.1021/jp073350h},
journal = {Journal of Physical Chemistry C},
number = 33,
volume = 111,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}
  • Monodisperse sub-10 nm (6.5 nm) sized Rh nanocrystals with (111) and (100) surface structures were synthesized by a seedless polyol reduction in ethylene glycol, with poly(vinylpyrrolidone) as a capping ligand. When using [Rh(Ac){sub 2}]{sub 2} as the metal precursor, (111)-oriented Rh nanopolyhedra containing 76% (111)-twined hexagons (in 2D projection) were obtained; whereas, when employing RhCl{sub 3} as the metal precursor in the presence of alkylammonium bromide, such as tetramethylammonium bromide and trimethyl(tetradecyl)ammonium bromide, (100)-oriented Rh nanocubes were obtained with 85% selectivity. The {l_brace}100{r_brace} faces of the Rh nanocrystals are stabilized by chemically adsorbed Br{sup -} ions from alkylammonium bromides, whichmore » led to (100)-oriented nanocubes. Monolayer films of the (111)-oriented Rh nanopolyhedra and (100)-oriented Rh nanocubes were deposited on silicon wafers in a Langmuir-Blodgett trough to make model 2D nanoarray catalysts. These nanocatalysts were active for CO oxidation by O{sub 2}, and the turnover frequency was independent of nanoparticle shape, consistent with that previously observed for Rh(111) and Rh(100) single crystals.« less
  • The present study describes in-situ synthesis of noble metal nano structures (MNCs) (Au and Ag) within a nematic liquid crystalline medium MBBA [N-(4-methoxybenzylidene)-4-butylaniline] without using any seed mediated growth protocol or without using any external stabilizing or reducing agent. Detailed Transmission Electron Microscopy (TEM) study indicates that apart from Kinetic based mechanism, the thermodynamical parameters also influence greatly the morphological evolution of these MNCs. The MNCs are of diverse shapes including nano prisms, hexagons, urchins, cubes, and rods which depend on the time of reaction and the choice of nanoparticle precursor.
  • Synthesis of monodisperse and shape-controlled colloidal inorganic nanocrystals (NCs) is of increasing scientific interest and technological significance. Recently, shape control of Pt, Pd, Ag, Au, and Rh NCs has been obtained by tuning growth kinetics in various solution-phase approaches, including modified polyol methods, seeded growth by polyol reduction, thermolysis of organometallics, and micelle techniques. Control of reduction kinetics of the noble metal precursors and regulation of the relative growth rates of low-index planes (i.e. {l_brace}100{r_brace} and {l_brace}111{r_brace}) via selective adsorption of selected chemical species are two keys for achieving shape modification of noble metal NCs. One application for noble metalmore » NCs of well-defined shape is in understanding how NC faceting (determines which crystallographic planes are exposed) affects catalytic performance. Rh NCs are used in many catalytic reactions, including hydrogenation, hydroformylation, hydrocarbonylation, and combustion reactions. Shape manipulation of Rh NCs may be important in understanding how faceting on the nanoscale affects catalytic properties, but such control is challenging and there are fewer reports on the shape control of Rh NCs compared to other noble metals. Xia and coworkers obtained Rh multipods exhibiting interesting surface plasmonic properties by a polyol approach. The Somorjai and Tilley groups synthesized crystalline Rh multipods, cubes, horns and cuboctahedra, via polyol seeded growth. Son and colleagues prepared catalytically active monodisperse oleylamine-capped tetrahedral Rh NCs for the hydrogenation of arenes via an organometallic route. More recently, the Somorjai group synthesized sizetunable monodisperse Rh NCs using a one-step polyol technique. In this Communication, we report the highly selective synthesis of catalytically active, monodisperse Rh nanocubes of < 10 nm by a seedless polyol method. In this approach, Br{sup -} ions from trimethyl(tetradecyl)ammonium bromide (TTAB) effectively stabilize the {l_brace}100{r_brace} faces of Rh NCs, and induce the evolution of nanocubes (Scheme 1). For a typical synthesis, 0.2 mmol RhCl{sub 3} hydrate, 1 mmol TTAB, and 4 mmol poly(vinylpyrrolidone) (PVP, Mw = 24,000), were added to 20 ml ethylene glycol at room temperature. The stock solution was heated to 80 C and purged for 20 min while stirring, producing a dark brown solution. The flask was then heated to 185 C and maintained at this temperature for 1.5 h under an Ar atmosphere. When the reaction was complete, an excess of acetone was added to the solution at room temperature to precipitate the nanocubes. The Rh nanocubes were separated by centrifugation and washed twice by precipitation/dissolution with ethanol/hexanes.« less