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Title: The preparation characterization and evaluation of novel Pt/C electrocatalysts with controlled porosity and cluster size.

Abstract

Abstract not provided.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1426964
Report Number(s):
SAND2007-1311J
Journal ID: ISSN 0959--9428; 526748
Grant/Contract Number:
AC04-94AL85000
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 17; Journal Issue: 31; Journal ID: ISSN 0959--9428
Country of Publication:
United States
Language:
English

Citation Formats

Coker, Eric Nicholas, Steen, William Arthur, Miller, James E., Miller, Jeffrey T., and Kropf, A. Jeremy. The preparation characterization and evaluation of novel Pt/C electrocatalysts with controlled porosity and cluster size.. United States: N. p., 2007. Web. doi:10.1039/b703916f.
Coker, Eric Nicholas, Steen, William Arthur, Miller, James E., Miller, Jeffrey T., & Kropf, A. Jeremy. The preparation characterization and evaluation of novel Pt/C electrocatalysts with controlled porosity and cluster size.. United States. doi:10.1039/b703916f.
Coker, Eric Nicholas, Steen, William Arthur, Miller, James E., Miller, Jeffrey T., and Kropf, A. Jeremy. Thu . "The preparation characterization and evaluation of novel Pt/C electrocatalysts with controlled porosity and cluster size.". United States. doi:10.1039/b703916f. https://www.osti.gov/servlets/purl/1426964.
@article{osti_1426964,
title = {The preparation characterization and evaluation of novel Pt/C electrocatalysts with controlled porosity and cluster size.},
author = {Coker, Eric Nicholas and Steen, William Arthur and Miller, James E. and Miller, Jeffrey T. and Kropf, A. Jeremy},
abstractNote = {Abstract not provided.},
doi = {10.1039/b703916f},
journal = {Chemistry of Materials},
number = 31,
volume = 17,
place = {United States},
year = {Thu Mar 01 00:00:00 EST 2007},
month = {Thu Mar 01 00:00:00 EST 2007}
}

Journal Article:
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  • The size of Pt particles introduced into the channels of ZSM-5 zeolite by two different preparation methods has been studied with EXAFS. ZSM-5 was loaded with 2 wt % Pt by ion exchange and by impregnation. By careful calcination of the catalysts the dispersion was maintained. The EXAFS measurements were performed on the reduced system. Analysis of the data showed that in the impregnated sample the platinum was present in particles which on average were smaller than the platinum particles in the ion-exchanged sample. These results corroborate earlier high-resolution electron microscopy measurements performed ex situ on the calcined catalysts. Moreover,more » the average particle size found from EXAFS analysis agrees well with the HREM results, indicating that dispersion is maintained during reduction. Both techniques indicate particles that exceed the dimensions of a zeolite cage at the intersection of the channels.« less
  • The cluster Ru{sub 3}Pt({mu}-H){l brace}{mu}{sub 4}-{eta}{sup 2}-C{triple bond}C(t-Bu){r brace}(CO){sub 9}(COD) decomposes in dichloromethane or toluene solution by elimination of a Pt atom and COD, affording orange crystals of the title complex Pt(Ru{sub 3}({mu}-H){l brace}{mu}{sub 4}-{eta}{sup 2}-C{triple bond}C(t-Bu){r brace}(CO){sub 9}){sub 2} (5) in 40-50% yield. Crystal data for 5: triclinic, space group P{bar 1}; a = 9.546 (2), b = 12.993 (2), c = 17.786 (2) {angstrom}; {alpha} = 72.97 (1), {beta} = 82.48 (1), {gamma} = 74.62 (2){degree}; V = 2030.4 (6) {angstrom}{sup 3}; Z = 2; final R (R{sub w}) values 0.033 (0.038) for 4,806 independent observed (I >more » 3.0{sigma}(I)) data. Complex 5 contains two Ru{sub 3} cluster units linked by a naked Pt atom, with each cluster unit bonded via one Ru atom and the {alpha}-carbon of the alkynyl ligand. Variable-temperature {sup 13}C NMR spectra show that the chiral metal framework undergoes racemization with an estimated {Delta}G{sup {double dagger}}{sub 266} of 57.1 ({plus minus}1.1) kJ mol{sup {minus}1}.« less
  • The kinetics of the oxygen reduction reaction (ORR) on Pt(hkl) surfaces is found to vary with crystal face in a different manner depending on the electrolyte. In perchloric acid, the variation in activity at 0.8 to 0.9 V is relatively small between the three low index faces, with activity increasing in the order (100) < (110) {approx} (111). A similar structure sensitivity was observed in KOH, increasing in the order (100) < (110) < (111), but with larger differences. In sulfuric acid, the variations in activity with crystal face were much larger, with the difference between the most active andmore » the least active being about two orders of magnitude, and increased in the opposite order (111) {much_lt} (100) < (110). The variations in activity with crystal face in perchloric acid and KOH arise from the structure sensitive inhibiting effect of OH{sub ads}, i.e., a strongly inhibiting effect on (100) and smaller effects on (110) and (111). The variations in activity with crystal face in sulfuric acid arise from highly structure specific adsorption of sulfate/bisulfate anions in this electrolyte, which has a strongly inhibiting effect on the (111) surface. The crystallite size effect for the ORR reported for supported Pt catalysts in sulfuric acid at ambient temperature is fully explained by applying the single crystal results to classical models of the variation in particle shape with size.« less
  • Nearly monodispersed 30 {+-} 4 A Ir {sub approximately 900} nanoclusters have been prepared by hydrogen reduction of a polyoxoanion-supported Ir(I) complex, (Bu{sub 4}N){sub 5}Na{sub 3}[(1,5-COD)Ir-P{sub 2}W{sub 15}Nb{sub 3}O{sub 62}] (1,5-COD is 1,5-cycloctadiene), in acetone solution. The Ir {sub approximately 900} nanoclusters can be isolated as a black powder and redissolved in acetone or CH{sub 3}CN to give a stable, amber solution. Extensive characterizations of the Ir {sub approximately 900} nanoclusters have been made by means of TEM, electron diffraction, electrophoresis, ultracentrifugation solution molecular-weight measurements, fast-atom bombardment mass spectroscopy, elemental analysis, and IR and UV-vis spectroscopy; their average chemical compositionmore » is [Ir(O) approximately 900 (P{sub 4}W{sub 30}Nb{sub 6}O{sub 123}{sup 16-}) {sub approximately 60}] (Bu{sub 4}N) {sub approximately 660} Na {sub approximately 300}, in which the polyoxoanion is found to be in its oxidized and Nb-O-Nb bridged aggregate form, P{sub 4}W{sub 30}Nb{sub 6}O{sub 123}{sup 16-}. Electron diffraction studies show that the nanoclusters consist of cubic close-packed (ccp) Ir metal cores; electrophoresis and other techniques establish that the nanoclusters are stabilized in solution by the adsorption of the polyoxoanions on their outer surfaces. Smaller, ca. 20-A Ir-300 nanoclusters have also been reproducibly prepared and characterized from (Bu{sub 4}N){sub 5}Na{sub 3}[(1,5-COD)Ir-P{sub 2}W{sub 15}Nb{sub 3}O{sub 62}] and from (Bu{sub 4}N){sub 4-} Na{sub 2}[(1,5-COD)Ir-SiW{sub 9}Nb{sub 3}O{sub 40}] during the catalytic hydrogenation of cyclohexene. 58 refs., 13 figs.« less
  • The present study investigated the effects of particle size on the adsorption performance of tungsten oxide nanoparticles. Nanoparticles 18-73 nm in diameter were prepared by evaporation of bulk tungsten oxide particles using a flame spray process. Annealing plasma-made tungsten oxide nanoparticles produced particles with diameters of 7-19 nm. The mechanism of nanoparticle formation for each synthetic route was examined. The low-cost, solid-fed flame process readily produced highly crystalline tungsten oxide nanoparticles with controllable size and a remarkably high adsorption capability. These nanoparticles are comparable to those prepared using the more expensive plasma process.