Carbon material for hydrogen storage
The present invention relates to carbon based materials that are employed for hydrogen storage applications. The material may be described as the pyrolysis product of a molecular precursor such as a cyclic quinone compound. The pyrolysis product may then be combined with selected transition metal atoms which may be in nanoparticulate form, where the metals may be dispersed on the material surface. Such product may then provide for the reversible storage of hydrogen. The metallic nanoparticles may also be combined with a second metal as an alloy to further improve hydrogen storage performance.
1. A method for forming a material for releasably storing hydrogen comprising:
supplying a cyclic quinone compound containing at least two ketone groups, wherein said quinone compound includes at least one metal alkoxide salt and optionally a halogen atom, wherein said quinone compound has a thermal degradation temperature;
pyrolyzing said cyclic quinone compound in air to a temperature that is within +/−20° C. of said thermal degradation temperature to provide a porous graphite oxide product comprising regions of graphene structure having multiple layers of hexagonally configured carbon atoms and one or more of the functional groups —COOH, —C═O and —OH and wherein said porous graphite oxide product has a BET surface area of 600 m 2 /g to 2500 m 2 /g;
incorporating metallic nanoparticles on a surface of said porous graphite oxide product, said metallic nanoparticles having a diameter of 1 nm to 100 nm and wherein said metallic nanoparticles consist essentially of an alloy of Pd and Hg having a ratio of Pd:Hg selected from 1:10 to 10:1 by weight;
wherein a porosity of the porous graphite oxide product remains undisturbed and an ability to interact with a gas due to diffusion and transport of the gas within porous regions of the porous graphite oxide product is not compromised due to the metallic nanoparticles;
wherein said porous graphite oxide product containing said metallic nanoparticles sorbs and desorbs hydrogen at levels of 8.0 to 10.0 percent by weight, at hydrogen pressures of 1-80 bars and isothermal temperatures selected from 20° C. to 30° C.; and
wherein the metallic nanoparticles are incorporated into said porous graphite oxide product at a level of 5 percent by weight to 25 percent by weight.
2. The method of claim 1 wherein said cyclic quinone compound has the following formula:
where X is a halogen and M + is a metal cation.
3. The method of claim 1 wherein said cyclic quinone compound has the following formula:
4. The method of claim 1 wherein said porous graphite oxide product has a pore volume of 0.40 to 4.50 cm 3 /g.
5. The method of claim 1 comprising pyrolyzing of said quinone compound in air at a temperature of 270° C. to 310° C.
6. The method of claim 1 , wherein the metallic nanoparticles comprises an alloy of Pd:Hg at an atomic ratio of 4:1.