Electrophoretic stabilization of freestanding pristine graphene foams with carbon nanotubes for enhanced optical and electrical response

Graphene materials, including three-dimensional foams, are commonly transferred from growth substrates using polymer stabilization processes. Even after harsh chemical and annealing treatments to remove the polymer, residues remain which compromise the electronic, thermal, gravimetric, and chemical properties of the graphene. To overcome this, we present a scalable, clean approach to stabilize graphene foams by conformal electrophoretic deposition of web-like networks of surfactant-free single-walled carbon nanotubes directly from polar solvents. We demonstrate these coatings to yield a pristine stabilized graphene material exhibiting 50x lower electrical resistance and a 10 cm^-1 optical red-shift in the Raman G′ double resonance mode in comparison to polymer-stabilized graphene. This approach enables the formation of three-dimensional architectures of nanomaterials without the adverse effects associated with residual impurities from polymer and chemical processing.