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Ozonolysis of carbon nanotubes

a carbon nanotube and ozonolysis technology, applied in the field of ozonolysis of carbon nanotubes, can solve the problems of not being able to economically scale the previously discussed electric arc discharge and laser deposition methods cannot be economically scaled up for such commercial or industrial production, and the simultaneous destruction of carbon nanotubes or carbon nanotube structures themselves. , the effect of enhancing electrochemical characteristics and reducing the number of steps

Inactive Publication Date: 2008-02-07
HYPERION CATALYSIS INT
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0036]Catalyst supports are preferably prepared by contacting or treating carbon nanotube aggregates, three dimensional networks or rigid porous structures with ozone at a temperature range of from 0° C. to 100° C. Preferably, the aggregates, three dimensional networks or rigid porous structures are contacted with ozone at or about room temperature. More preferably, the aggregates, three dimensional networks or rigid porous structures are contacted with ozone at a temperature range between 0° C. and 60° C. and most preferably between 20° C. and 50° C. Catalyst support structures functionalized using ozone exhibit higher acid titer, thus enabling higher catalyst loading and better retention of their original support structure and integrity.
[0037]Electrochemical capacitors assembled from electrodes made from the ozone treated carbon nanotubes of the invention exhibit enhanced electrochemical characteristics, such as specific capacitance.

Problems solved by technology

The differences make graphite and carbon black poor predictors of carbon nanotube chemistry.
The previously discussed electric arc discharge and laser deposition methods cannot economically be scaled up for such commercial or industrial production.
However, a common unwanted side effect is the simultaneous destruction of the carbon nanotubes or carbon nanotube structures themselves.
And thus, not only is the strength and integrity of the carbon nanotube or carbon nanotube structure compromised, but there is also a restricted limit as to how much oxygen containing moieties can be deposited onto the carbon nanotube or carbon nanotube structure.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0150]Ozone was generated via an air purifier made by Del Industry, San Luis Obispo, Calif., which can generate ozone at a rate of 250 mg / hr. A mixture of ozone and air (0.29% ozone) at a flow rate of 1200 mL / min was then passed though a 1-inch (OD) reactor tube packed with dry as-made fibrils. The weight of fibrils before and after ozone treatment were recorded. The reaction was allowed to proceed for a period of 3 to 45 hours at room temperature.

[0151]In a separate experiment, 20 grams of as-made fibrils were placed in a flask containing 500 mL 30% or 60% nitric acid. The reaction flask was then heated to reflux temperature of 95-120° C. for 4-6 hours. After the reaction was stopped, the fibrils were cooled to room temperature, filtered, and washed with water until neutral. In another separate experiment, 20 grams of as-made fibrils were placed in a flask containing 376.2 grams of 30% H2O2 in molar ratio of 1:2. The temperature was set to be in the vicinity of 35° C., but it rose ...

example 2

[0155]3 grams of dry fibrils was placed in a vertical reactor and ozone-containing air was passed through them at room temperature. The reactor was shut off periodically at every hour and the total weight of fibrils plus the reactor tube were measured on an electric balance. The weight gain of fibrils against reaction time was then obtained after tarring off the reactor weight.

[0156]The results of this measurement are displayed in FIG. 7, which shows that the sample's weight increased over the course of reaction and leveled off after approximately 15 hours of reaction lime.

example 3

[0157]Various oxidized fibrils prepared according to the methods in Example 1 such as Samples 1-3 and 5-7 were measured to determine their relative amount of acidic groups through titration. 0.25 gram of each sample was placed into a flask containing 300 mL D.I. water and the slurry was titrated with 0.1N NaOH. The consumption of NaOH was translated into the quantity of total surface acidic groups as meq / g.

TABLE 3Measurement of surface acidic groups through titration.Sample weightWeight changeTiterSample(g)Oxidant(%)(meq / g)13O3 / air13.951.4523O3 / air8.01.07310O3 / air10.401.5753O3 / air12.121.1682030% HNO3−15.28 1.2062060% HNO3−6.350.5872030% H2O2−4.0 0.128

[0158]As shown in Table 3, more acidic groups can be deposited onto the surface of carbon nanotubes when oxidized with ozone at room temperature than with other oxidizing agents such as nitric acid or hydrogen peroxide. In other words, treatment of carbon nanotubes with ozone at room temperature will yield nanotubes with a higher titer ...

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Abstract

Methods of treating single walled and multiwalled carbon nanotubes with ozone are provided. The carbon nanotubes are treated by contacting the carbon nanotubes with ozone at a temperature range between 0° C. and 100° C. to yield functionalized nanotubes which are greater in weight than the untreated carbon nanotubes. The carbon nanotubes treated according to methods of the invention can be used to prepare complex structures such as three dimensional networks or rigid porous structures which can be utilized to form electrodes for fabrication of improved electrochemical capacitors. Useful catalyst supports are prepared by contacting carbon nanotube structures such as carbon nanotube aggregates, three dimensional networks or rigid porous structures with ozone in the temperature range between 0° C. and 100° C.

Description

CROSS REFERENCE INFORMATION[0001]This application claims priority to and the benefit of U.S. Provisional Application Ser. No. 60 / 720,806, filed Sep. 26, 2005, and of U.S. Provisional Application Ser. No. 60 / 621,132, filed Oct. 22, 2004, all of which are hereby incorporated by reference in their entirety.BACKGROUND OF THE INVENTION[0002]1. Field of Invention[0003]The invention relates to methods of treating the surface of single walled and multiwalled carbon nanotubes with ozone. The invention also encompasses methods of making aggregates of ozone-treated nanotubes, and methods of using the same. The invention further relates to methods of making complex structures such as three dimensional networks or rigid porous structures comprised of such ozone-treated carbon nanotubes linked to one another. The invention also includes methods of making a catalyst support from aggregates, three dimensional networks, or rigid porous structures that have been treated with ozone.[0004]2. Descriptio...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): D01F9/12
CPCB82Y30/00B82Y40/00C01B31/0273C01B2202/02Y02E60/13C01B2202/36H01G9/058H01G11/34H01G11/36C01B2202/06C01B32/174H01G11/22C01B32/00B82B3/00C07C27/06
Inventor MA, JUNCHISHTI, ASIFNGAW, LEINFISCHER, ALANBRADEN, ROBERT
Owner HYPERION CATALYSIS INT
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