Method for preparing functionalized carbon materials

Abstract

The present invention belongs to the field of new materials technology and discloses a green method for preparing functionalized carbon materials. The present invention can use potassium ferrate(VI) as an oxidant and mechanical milling as a reaction technique for oxidizing carbon materials in a preparation of functionalized carbon materials having oxygen-containing functional groups. Compared with the prior art, the present invention provides a method that combines an environmentally friendly oxidant with an environmentally friendly reaction process. The oxidant potassium ferrate(VI) is a green oxidant without producing any toxic byproducts. The reaction process is solvent-free, facilitated by milling the solid mixture of carbon materials and the oxidant. Thus, the present invention provides an environmentally friendly method for preparing oxidatively functionalized carbon materials, which is of promotion value.

Claims

1. A method for preparing a functionalized carbon material, comprising milling a carbon material and potassium ferrate(VI) to oxidize the carbon material to produce an oxidized carbon material, wherein the carbon material includes carbon nanotubes, the carbon nanotubes include one or more selected from the group consisting of multiwalled carbon nanotubes, double-walled carbon nanotubes, and single-walled carbon nanotubes, the functionalized carbon material has oxygen-containing groups on a surface thereof, oxidation between the carbon material and potassium ferrate(VI) does not need any solvent, and the mass ratio of the carbon material to potassium ferrate(VI) is 1:5-50.

2. The method according to claim 1, wherein the method further includes performing a post treatment of the oxidized carbon material.

3. The method according to claim 1, wherein the milling is a manual milling or a machine milling, the manual milling is performed with a manual milling or grinding or dispersing device, and the machine milling is performed with a machine milling or grinding or dispersing device.

4. The method according to claim 3, wherein the manual milling or grinding or dispersing device includes at least one selected from the group consisting of a mortar and a pestle, and the machine milling or grinding or dispersing device includes planetary ball mill machine, vibration ball mill machine, stirring dispersing machine, or grinder.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) Hereinafter, the present invention will be described in detail with reference to embodiments.

Embodiment 1

(2) This embodiment provides an environmentally friendly mechanochemical method for functionalizing multiwalled carbon nanotubes by manual milling, including steps of:

(3) First, 0.1 g of multiwalled carbon nanotubes (diameter 15-30 nm, length >10 m) and 1 g of potassium ferrate(VI) were grinded together in an agate mortar for 30 minutes. Then the resulting mixture was slowly added into 50 ml of 2 M HCl and settled for 2 hours, followed by centrifugation at 3500 rpm for 3 min to obtain solids. The obtained solids were then dispersed in water under brief sonication, followed by filtration (0.22 m PTFE membranes) and successive washing with 2 M HCl, water, and alcohol. The resultant product was dried at 60 C. in a vacuum oven to obtain the oxidized multiwalled carbon nanotubes.

(4) Both the samples of the multiwalled carbon nanotubes and the oxidized multiwalled carbon nanotubes were analyzed by X-ray photoelectron spectroscopy (XPS). The results show that the multiwalled carbon nanotubes have an O/C (oxygen/carbon) ratio of 3.5%, and that the oxgened multiwalled carbon nanotubes have an O/C ration of 8.4%.

Embodiment 2

(5) Embodiment 2 provides an environmentally friendly solvent-free mechanochemical method for oxidation of multiwalled carbon nanotubes using a ball mill. The method includes the following steps:

(6) First, 0.2 g of multiwalled carbon nanotubes (diameter 15-30 nm, length >10 m) and 4 g of potassium ferrate(VI) were briefly ground in an agate mortar to obtain a mixture. The mixture was then introduced into a 50 mL stainless milling jar together with 50 g of 5 mm-diameter stainless steel balls. Ball milling was performed at a rotational speed of 300 rpm for 2 hours. Then the resulting mixture was slowly added into 50 ml of 2 M HCl and settled for 2 hours, followed by centrifugation at 3500 rpm for 3 min to obtain solids. The obtained solids were then dispersed in water under brief sonication, followed by filtration (0.22 m PTFE membranes) and successive washing with 2 M HCl, water, and alcohol. The resultant product was dried at 60 C. in a vacuum oven to obtain the oxidized multiwalled carbon nanotubes.

(7) Samples of the multiwalled carbon nanotubes and the oxidized multiwalled carbon nanotubes were analyzed by XPS, showing the O/C ratio increased from 3.5% to 11.3%. The obtained product has excellent dispersibility in a variety of solvents, and solubility in water of 4.8 mg/mL.

Embodiment 3

(8) Embodiment 3 provides a solvent-free mechanochemical method for green oxidation of single-walled carbon nanotubes using a ball mill. The method includes the following steps:

(9) First, 0.4 g of single-walled carbon nanotubes (diameter 1-2 nm, length 5-30 m) and 8 g of potassium ferrate(VI) were briefly grinded in an agate mortar to mix them together. The mixture was then introduced into a 100 mL stainless milling jar together with 100 g of 5 mm-diameter stainless steel balls. Ball milling was performed at a rotational speed of 300 rpm for 24 hours. Then the resulting mixture was slowly added into 100 ml of 2 M HCl and settled for 2 hours, followed by centrifugation at 3500 rpm for 3 min to obtain solids. The obtained solids were then dispersed in water under brief sonication, followed by filtration (0.22 m PTFE membranes) and successive washing with 2 M HCl, water, and alcohol. The resultant product was dried at 60 C. in a vacuum oven to obtain the oxidized single-walled carbon nanotubes.

(10) Samples of the single-walled nanotubes and the oxidized single-walled carbon nanotubes were analyzed by XPS, showing the O/C ratio increased from 0.5% to 18.4%. Raman spectra of the samples showed that the D/G intensity ratio increased from 0.03 to 0.35.

Embodiment 4

(11) Embodiment 4 provides a solvent-free mechanochemical method for green oxidation of graphite using a ball mill. The method includes the following steps:

(12) 0.5 g of graphite (325 mesh) and 3 g of potassium ferrate(VI) were added into a 100 mL stainless milling jar together with 50 g of 5 mm-diameter stainless steel balls. Ball milling was performed at a rotational speed of 500 rpm for 48 hours. Then the resulting mixture was slowly added into 100 ml of 2 M HCl and settled for 2 hours, followed by centrifugation at 3500 rpm for 3 min to obtain solids. The obtained solids were then dispersed in water under brief sonication, followed by filtration (0.22 m PTFE membranes) and successive washing with 2 M HCl and water. The resultant product was then sonicated in water to obtain a stable colloidal dispersion of oxidized graphitic nanoplatelets.

(13) The above description of embodiments are only for easy understanding and using of the present invention by one of ordinary skills in this art. Those skilled in this art can easily make various changes to these embodiments and apply the general principle described here to other embodiments without creative work. Therefore, the present invention is not limited to the above-described embodiments, and modifications and changes made without departing from the scope of the present invention by those skilled in this art according to the disclosure of the present invention would fall within the scope of the present invention.