Humic acid-derived conductive foams and devices

1. A humic acid-derived foam composed of multiple pores and pore walls, wherein said pore walls contain 1-10 layers of humic acid-derived hexagonal carbon atomic planes or sheets, wherein stacks of 2-10 layers of stacked hexagonal carbon atomic planes have an inter-plane spacing d 002 from 0.3354 nm to 0.60 nm as measured by X-ray diffraction, and said hexagonal carbon atomic planes or sheets contain 0.01% to 25% by weight of non-carbon elements, and wherein said humic acid is selected from a group consisting of oxidized humic acid, reduced humic acid, fluorinated humic acid, chlorinated humic acid, brominated humic acid, iodized humic acid, hydrogenated humic acid, nitrogenated humic acid, doped humic acid, chemically functionalized humic acid, and a combination thereof.

2. The humic acid-derived foam of claim 1 , wherein said foam has a density from 0.005 to 1.7 g/cm 3 , a specific surface area from 50 to 3,200 m 2 /g, a thermal conductivity of at least 100 W/mK per unit of specific gravity, and/or an electrical conductivity no less than 500 S/cm per unit of specific gravity.

3. The humic acid-derived foam of claim 1 , wherein said foam has a density from 0.01 to 1.5 g/cm 3 or an average pore size from 2 nm to 50 nm.

4. The humic acid-derived foam of claim 1 , wherein said foam contains a content of non-carbon elements in the range of 0.01% to 20% by weight and said non-carbon elements include an element selected from oxygen, fluorine, chlorine, bromine, iodine, nitrogen, hydrogen, or boron.

5. The humic acid-derived foam of claim 1 , wherein said pore walls contain fluorinated humic acid and said foam contains a fluorine content from 0.01% to 25% by weight.

6. The humic acid-derived foam of claim 1 , wherein said pore walls contain oxidized humic acid and said foam contains an oxygen content from 0.01% to 25% by weight.

7. The humic acid-derived foam of claim 1 , wherein said foam has a specific surface area from 200 to 3,000 m 2 /g or a density from 0.1 to 1.2 g/cm 3 .

8. The humic acid-derived foam of claim 1 , which is in a continuous-length roll sheet form having a thickness from 100 nm to 10 cm and a length of at least 2 meters and is produced from a roll-to-roll process.

9. The humic acid-derived foam of claim 1 , wherein said foam has an oxygen content or non-carbon content less than 1% by weight, and said pore walls have stacked hexagonal carbon atomic planes having an inter-planar spacing less than 0.35 nm, a thermal conductivity of at least 200 W/mK per unit of specific gravity, and/or an electrical conductivity no less than 1,000 S/cm per unit of specific gravity.

10. The humic acid-derived hybrid foam of claim 1 , wherein said foam has an oxygen content or non-carbon content less than 0.01% by weight and said pore walls contain stacked hexagonal carbon atomic planes having an inter-planar spacing less than 0.34 nm, a thermal conductivity of at least 300 W/mK per unit of specific gravity, and/or an electrical conductivity no less than 1,500 S/cm per unit of specific gravity.

11. The humic acid-derived foam of claim 1 , wherein said foam has an oxygen content or non-carbon content no greater than 0.01% by weight and said pore walls contain stacked hexagonal carbon atomic planes having an inter-planar spacing less than 0.336 nm, a thermal conductivity of at least 350 W/mK per unit of specific gravity, and/or an electrical conductivity no less than 2,000 S/cm per unit of specific gravity.

12. The humic acid-derived foam of claim 1 , wherein said foam has pore walls containing stacked hexagonal carbon atomic planes having an inter-planar spacing less than 0.336 nm, a thermal conductivity greater than 400 W/mK per unit of specific gravity, and/or an electrical conductivity greater than 3,000 S/cm per unit of specific gravity.

13. The humic acid-derived foam of claim 1 , wherein the pore walls contain stacked hexagonal carbon atomic planes having an inter-planar spacing less than 0.337 nm and a mosaic spread value less than 1.0.

14. The humic acid-derived foam of claim 1 , wherein said pore walls contain a 3D network of interconnected hexagonal carbon atomic planes.

15. The humic acid-derived foam of claim 1 , wherein said foam contains meso-scaled pores having a pore size from 2 nm to 50 nm.

16. An oil-removing or oil-separating device containing the humic acid-derived foam of claim 1 as an oil-absorbing element.

17. A solvent-removing or solvent-separating device containing the humic acid-derived foam of claim 1 as a solvent-absorbing or solvent-separating element.

18. A method to separate oil from water, said method comprising the steps of:

a. providing an oil-absorbing element comprising the humic acid-derived foam of claim 1 ;

b. contacting an oil-water mixture with said element, which absorbs the oil from the mixture;

c. retreating the element from the mixture and extracting the oil from the element; and

d. reusing the element.

19. A method to separate an organic solvent from a solvent-water mixture or from a multiple-solvent mixture, said method comprising the steps of:

a. providing an organic solvent-absorbing or solvent-separating element comprising the humic acid-derived foam of claim 1 ;

b. bringing said element in contact with an organic solvent-water mixture or a multiple-solvent mixture containing a first solvent and at least a second solvent;

c. allowing said element to absorb the organic solvent from the mixture or separate said first solvent from said at least second solvent;

d. retreating the element from the mixture and extracting the organic solvent or first solvent from the element; and

e. reusing the element.

20. A thermal management device containing the humic acid-derived foam of claim 1 as a heat spreading or heat dissipating element.

21. The thermal management device of claim 20 , which contains a device selected from a group consisting of a heat exchanger, heat sink, heat pipe, high-conductivity insert, conductive plate between a heat sink and a heat source, heat-spreading component, heat-dissipating component, thermal interface medium, and a thermoelectric or Peltier cooling device.