Uniform nanoporous graphene sponge from natural polysaccharides as a metal-free electrocatalyst for hydrogen generation
[EN] Structuring of graphene as graphene sponges in the submicrometric scale has been achieved by using silica spheres (80 nm diameter) as hard templates and chitosan or alginate as precursor of defective N-doped or undoped graphene, respectively. The resulting defective N-doped graphene sponge exhibits a remarkable activity and stability for hydrogen evolution reaction with onset at 203 mV for a current density of 0.5 mA cm(-2) with a small Tafel plot slope of 69.7 mV dec(-1). In addition, the graphene sponge also exhibits a high double layer capacitance of 11.65 mF cm(-2). Comparison with an analogous N-doped graphene sample shows that this electrochemical properties derive from the spati…
Polystyrene as Graphene Film and 3D Graphene Sponge Precursor
[EN] Polystyrene as a thin film on arbitrary substrates or pellets form defective graphene/graphitic films or powders that can be dispersed in water and organic solvents. The materials were characterized by visible absorption, Raman and X-ray photoelectron spectroscopy, electron and atomic force microscopy, and electrochemistry. Raman spectra of these materials showed the presence of the expected 2D, G, and D peaks at 2750, 1590, and 1350 cm(-1), respectively. The relative intensity of the G versus the D peak was taken as a quantitative indicator of the density of defects in the G layer.