Ambient Pressure Synthesis of Aerogel-Like Vanadium Oxide and Molybdenum Oxide

Harreld, John H.; Dong, Winny; Dunn, Bruce

doi:10.1016/s0025-5408(98)00022-1

Cited by 73 publications

(59 citation statements)

References 23 publications

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“…Multi-step solvent exchange was undertaken with nonpolar solvents to avoid the capillary action associated with drying and shrinkage [38,39]. First the gels were washed with acetone for 3 days in a capped vial, exchanging the acetone once per day.…”

Section: Aerogel Preparationmentioning

confidence: 99%

Favourable influence of hydrophobic surfaces on protein structure in porous organically-modified silica glasses

et al. 2008

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Organically-modified siloxanes were used as host materials to examine the influence of surface chemistry on protein conformation in a crowded environment. The sol-gel materials were prepared from tetramethoxysilane and a series of monosubstituted alkoxysilanes, RSi(OR′) 3 , featuring alkyl groups of increasing chain length in the R-position. Using circular dichroism spectroscopy in the far-UV region, apomyoglobin was found to transit from an unfolded state to a native-like helical state as the content of the hydrophobic precursor increased from 0-15%. At a fixed molar content of 5% RSi(OR') 3 , the helical structure of apomyoglobin increased with the chain length of the R-group, i.e. methyl < ethyl < n-propyl < n-butyl < n-hexyl. This trend also was observed for the tertiary structure of ribonuclease A, suggesting that protein folding and biological activity are sensitive to the hydrophilic/hydrophobic balance of neighboring surfaces. The observed changes in protein structure did not correlate with total surface area or the average pore size of the modified glasses, but scanning electron microscopy images revealed an interesting relationship between surface morphology and alkyl chain length. The unexpected benefit of incorporating a low content of hydrophobic groups into a hydrophilic surface may lead to materials with improved biocompatibility for use in biosensors and implanted devices.

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Section: Aerogel Preparationmentioning

confidence: 99%

Favourable influence of hydrophobic surfaces on protein structure in porous organically-modified silica glasses

et al. 2008

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“…•ambigel'). 17 The ambigel was heated in air at 125°C to remove residual solvent. For preparing standard electrodes, the V 2 0 5 was ground to a fine powder, suspended in cyclohexane and combined with KJB (5,9, and 17 wt% as described below) and poly(vinylidine fluoride) (PVDF from Aldrich).…”

Section: Introductionmentioning

confidence: 99%

“…As shown in Table I, the properties of pristine vanadium oxide ambigel after immersion in propylene carbonate are virtually identical to the characteristics of comparable samples which have not been immersed. 17 ' 24 The fact that the aerogel morphology is unaffected by exposure to the organic electrolyte is an important consideration if these materials are to be viable electrodes for lithium secondary batteries.…”

mentioning

confidence: 99%

Vanadium Oxide-Carbon Nanotube Composite Electrodes for Use in Secondary Lithium Batteries

Sakamoto

Dunn

2002

J. Electrochem. Soc.

250

132

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)Office of Naval Research 800 North Quincy Street Arlington, VA 22217 PERFORMING ORGANIZATION REPORT NUMBERTechnical Report #17 SPONSOR/MONITOR'S ACRONYM(S) SPONSORING/MONITORING AGENCY REPORT NUMBER DISTRIBUTION AVAILABILITY STATEMENTReproduction in whole, or in part, is permitted for any purpose of the United States Government. This document has been approved for public release and sale; its distribution is unlimited. SUPPLEMENTARY NOTES Submitted for publication in: Journal of the Electrochemical Society ABSTRACTSingle-wall carbon nanotubes were used to form the electronically conducting network in lithium intercalation electrodes that incorporated vanadium oxide aerogels as the active material. Sol-gel methods were developed which integrated the nanotubes with V 2 0 5 aerogel synthesis. The similarities in morphology and dimensional scale for the nanotubes and V 2 0 5 ribbons enabled excellent electrical contact to be made between the two phases without seriously affecting the aerogel nanostructure. Intimate contact was established between the two phases at the nanodimensional level while the high pore volume of the aerogel provided electrolyte access throughout the composite material. The electrodes exhibited specific capacities in excess of 400 mAh/g at high discharge rates and retained this level of capacity on cycling. Single-wall carbon nanotubes were used to form the electronically conducting network in lithium intercalation electrodes that incorporated vanadium oxide aerogels as the active material. SUBJECT TERMSSol-gel methods were developed which integrated the nanotubes with V 2 0 5 aerogel synthesis.The similarities in morphology and dimensional scale for the nanotubes and V 2 0 5 ribbons enabled excellent electrical contact to be made between the two phases without seriously affecting the aerogel nanostructure. Intimate contact was established between the two phases at the nanodimensional level while the high pore volume of the aerogel provided electrolyte access throughout the composite material. The electrodes exhibited specific capacities in excess of 400 mAh/g at high discharge rates and retained this level of capacity on cycling.*

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“…An ambientpressure approach (termed 'ambigels') was accomplished by drying the precursor gel using nonpolar solvents such as hexane and cyclohexane. 10 By using these two methods, mesoporous vanadium oxide materials with surface areas ranging from ~ 150 m/g to 300 m 2 /g were synthesized (Table 1). For comparison, a low surface area vanadium oxide xerogel (< 10 m 2 /g) was also investigated.…”

mentioning

confidence: 99%