High temperature oxygen treated carbon aerogels
Disclosed here is a method for increasing the hydrophilicity of a carbon aerogel, comprising heating the carbon aerogels under air or a gas having a higher concentration of oxygen than air at a temperature of about 200°-500° C. to obtain an activated carbon aerogel. Also disclosed include an activated carbon aerogel obtained by the method, an electrode comprising the activated carbon aerogel, and a supercapacitor or capacitive deionization device comprising the electrode.
1. A method for increasing the hydrophilicity of a carbon aerogel, comprising heating the carbon aerogels under air or a gas having a higher concentration of oxygen than air at a temperature of about 200°-500° C. to obtain an activated carbon aerogel, wherein the carbon aerogel is heated in a chamber under flowing gas having a flow rate of about 5 sccm/cm 2 or less of the chamber's cross sectional area, and wherein the activated carbon aerogel has a wetting angle of about 1° or less.
2. The method of claim 1 , wherein the carbon aerogel is heated under air.
3. The method of claim 1 , wherein the carbon aerogel is heated at a temperature of about 350-450° C.
4. The method of claim 1 , wherein the carbon aerogel is heated for about 30-300 minutes.
5. The method of claim 1 , wherein the carbon aerogel is obtained by:
providing a reaction mixture comprising resorcinol, formaldehyde, and at least one catalyst,
curing said reaction mixture to form a wet gel,
drying said wet gel to produce a dry gel, and
pyrolyzing said dry gel to produce the carbon aerogel.
6. The method of claim 1 , wherein the activated carbon aerogel has a wetting angle that is decreased by at least about 30° compared to a corresponding unactivated carbon aerogel.
7. The method of claim 1 , wherein the activated carbon aerogel has a wetting angle that is decreased by at least about 45° compared to a corresponding unactivated carbon aerogel.
8. The method of claim 1 , wherein the activated carbon aerogel has an atomic oxygen content of about 5-30 at. % on its surface.
9. The method of claim 1 , wherein the activated carbon aerogel has an atomic oxygen content of about 10-25 at. % on its surface.
10. The method of claim 1 , wherein the activated carbon aerogel has an atomic oxygen content on its surface that is at least about 10 at. % more than a corresponding carbon aerogel activated under CO 2 .
11. The method of claim 1 , wherein the activated carbon aerogel has an atomic oxygen content on its surface that is at least about 15 at. % more than a corresponding carbon aerogel activated under CO 2 .
12. The method of claim 1 , wherein the activated carbon aerogel has a capacity of at least about 100 F/g or at least about 50 F/cm 3 .
13. The method of claim 1 , wherein the activated carbon aerogel has a capacity of about 120-150 F/g or about 50-70 F/cm 3 .
14. The method of claim 1 , wherein the activated carbon aerogel has a weight loss of about 50 wt. % of less compared to a corresponding unactivated carbon aerogel.