Hollow graphene balls and devices containing same
Provided is a powder mass of multiple individual hollow graphene balls, wherein at least one of the hollow graphene balls has a graphene shell composed of graphene sheets bonded by a carbon material and a hollow core enclosed by the graphene shell. These hollow graphene sheets can be used in a broad array of applications, such as for thermal management, for separating an organic solvent from a solvent-water mixture, and for separating oil from water.
1. A powder mass of multiple individual hollow graphene balls, wherein at least one of said hollow graphene balls has a graphene shell composed of graphene sheets bonded by a carbon material and a hollow core enclosed by said graphene shell, wherein said multiple individual hollow graphene balls are distinct from each other and not part of a foam.
2. The powder mass of claim 1 , wherein said graphene shell comprises single-layer or few-layer graphene sheets chemically bonded by a carbon material having a carbon material-to-graphene weight ratio from 1/200 to ½.
3. The powder mass of claim 1 , wherein said graphene shell comprises few-layer graphene sheets comprising 2-10 layers of stacked graphene planes having an inter-plane spacing d 002 from 0.3354 nm to 0.36 nm as measured by X-ray diffraction.
4. The powder mass of claim 1 , wherein said hollow graphene balls have a density from 0.01 to 1.7 g/cm 3 , and a specific surface area from 50 to 3,000 m 2 /g.
5. The powder mass of claim 1 , wherein said hollow graphene balls have a specific surface area from 50 to 3,000 m 2 /g.
6. An oil-removing or oil-separating device containing said hollow graphene balls of claim 1 as an oil-absorbing element.
7. A solvent-removing or solvent-separating device containing said hollow graphene balls of claim 1 as a solvent-absorbing or solvent-separating element.
8. A thermal management device comprising said hollow graphene balls of claim 1 as a heat-conducting, heat spreading or heat dissipating element.
9. The thermal management device of claim 8 , which comprises a device selected from 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, or thermoelectric or Peltier cooling device.
10. The powder mass of claim 1 , further including a binder resin that binds together the multiple individual hollow graphene balls.