From biomass wastes to large-area, high-quality, N-doped graphene: catalyst-free carbonization of chitosan coatings on arbitrary substrates.

Chitosan is a N-containing biopolymer that can form high-quality films on glass, quartz, metals and other hydrophilic surfaces. Pyrolysis of chitosan films under argon at 800 °C and under inert atmosphere gives rise to high-quality single layer N-doped graphene films (over 99% transmittance) as evidenced by XPS, Raman spectroscopy, and TEM imaging.