Nanoporous metal-carbon composite
Described here is a metal-carbon composite, comprising (a) a porous three-dimensional scaffold comprising one or more of carbon nanotubes, graphene and graphene oxide, and (b) metal nanoparticles disposed on said porous scaffold, wherein the metal-carbon composite has a density of 1 g/cm 3 or less, and wherein the metal nanoparticles account for 1 wt. % or more of the metal-carbon composite. Also described are methods for making the metal-carbon composite.
1. A method for making a metal-carbon composite, comprising (a) providing an aqueous mixture comprising (i) at least one of carbon nanotube and graphene oxide and (ii) at least one metal salt or metal nanowire; (b) freezing the mixture to obtain a cryo-composite; (c) drying the cryo-composite to obtain a dry composite; and (d) reducing the dry composite to obtain a metal-carbon composite comprising metal nanoparticles consisting essentially of elemental metal.
2. The method of claim 1 , wherein the metal salt or metal nanowire comprises a metal selected from the group consisting of Cu, Ag, Au, Pt, Pd, Co, Ni, W, Mo, Fe, and Ru.
3. The method of claim 1 , wherein the metal salt or metal nanowire comprises a metal selected from the group consisting of Cu, Ag, Au, and Pt.
4. The method of claim 1 , wherein the metal salt or metal nanowire is a copper or silver salt or a copper or silver nanowire.
5. The method of claim 1 , wherein step (d) comprises pyrolyzing the dry composite in a reducing environment, wherein the metal nanoparticles account for 5 wt. % or more of the metal-carbon composite, and wherein carbon and metal account for 90 at. % or more of the metal-carbon composite.
6. A method for making an aerogel, comprising (a) providing an aqueous mixture comprising (i) graphene oxide, (ii) at least one metal salt, and (iii) at least one catalyst; (b) curing the reaction mixture to produce a wet gel; (c) washing and drying the wet gel to obtain a metal-graphene oxide aerogel comprising a graphene oxide scaffold and metal nanoparticles consisting essentially of elemental metal.
7. The method of claim 6 , wherein the metal salt comprises a metal selected from the group consisting of Cu, Ag, Au, Pt, Pd, Co, Ni, W, Mo, Fe, and Ru.
8. The method of claim 6 , wherein the metal salt comprises a metal selected from the group consisting of Cu, Ag, Au, and Pt.
9. The method of claim 6 , wherein the metal salt is a gold salt.
10. The method of claim 6 , further comprising (d) reducing the metal-graphene oxide aerogel to produce a metal-graphene aerogel comprising a graphene scaffold, wherein carbon and metal account for 90 at. % or more of the metal-graphene aerogel.
11. The method of claim 6 , further comprising (e) removing the graphene oxide scaffold to obtain a metal aerogel, wherein metal accounts for 90 at. % or more of the metal aerogel.
12. A method for making a metal-carbon composite, comprising (a) providing an aqueous mixture comprising (i) at least one carbon nanotube, (ii) at least one metal nanoparticle, and (iii) at least one surfactant; (b) curing the reaction mixture to produce a wet gel; (c) washing and drying the wet gel to obtain a carbon nanotube-metal nanoparticle composite comprising metal nanoparticles consisting essentially of elemental metal.
13. The method of claim 12 , further comprising (d) reducing the carbon nanotube-metal nanoparticle composite to produce a metal-carbon composite, wherein the metal nanoparticles account for 5 wt. % or more of the metal-carbon composite, and wherein carbon and metal account for 90 at. % or more of the metal-carbon composite.
14. The method of claim 12 , wherein the metal nanoparticle comprises a metal selected from the group consisting of Cu, Ag, Au, Pt, Pd, Co, Ni, W, Mo, Fe, and Ru.
15. The method of claim 12 , wherein the metal nanoparticle comprises a metal selected from the group consisting of Cu, Ag, Au, and Pt.
16. The method of claim 12 , wherein the metal nanoparticle is a copper nanoparticle.
17. A method for making a metal-carbon composite, comprising (a) providing a carbon aerogel; (b) immersing said carbon aerogel in an aqueous metal salt solution; (c) freeze drying the carbon aerogel in a vacuum to obtain a metal salt-impregnated carbon aerogel; and (d) reducing the metal salt-impregnated carbon aerogel to obtain a metal-carbon composite comprising metal nanoparticles consisting essentially of elemental metal.
18. The method of claim 17 , wherein the metal salt comprises a metal selected from the group consisting of Cu, Ag, Au, Pt, Pd, Co, Ni, W, Mo, Fe, and Ru.
19. The method of claim 17 , wherein the metal salt comprises a metal selected from the group consisting of Cu, Ag, Au, and Pt.
20. The method of claim 17 , wherein the metal salt is a platinum salt or a copper salt.