Quality Improvement of Few-Layers Defective Graphene from Biomass and Application for H2 Generation

Pyrolysis of filmogenic natural polymers gives rise to the formation of films of few-layers defective, undoped, and doped graphenes with low electrical conductivity (3000 to 5000 ohm /sq). For the sake of valorization of biomass wastes, it would be of interest to decrease the density of structural defects in order to increase the conductivity of the resulting few-layers graphene samples. In the present study, analytical and spectroscopic evidence is provided showing that by performing the pyrolysis at the optimal temperature (1100 degrees C), under a low percentage of H-2, a significant decrease in the density of defects related to the presence of residual oxygen can be achieved. This improvement in the quality of the resulting few-layers defective graphene is reflected in a decrease by a factor of about 3 or 5 for alginic acid and chitosan, respectively, of the electrical resistance. Under optimal conditions, few-layers defective graphene films with a resistance of 1000 ohm /sq were achieved. The electrode made of high-quality graphene prepared at 1100 degrees C under Ar/H-2 achieved a H-2 production of 3.62 mu mol with a positive applied bias of 1.1 V under LED illumination for 16 h.