Quality Improvement of Few-Layers Defective Graphene from Biomass and Application for H-2 Generation

[EN] 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. Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and RTI2018-098237-B-C21) and Generalitat Valencia (Prometeo 2017/083) is gratefully acknowledged. J. H. thanks the Chinese Scholarship Council (CSC) for supporting his doctoral stage at Valencia. A. P. also acknowledges the Spanish Ministry of Economy and Competitiveness for a Ramon y Cajal research associate contract. He, J.; Anouar, A.; Primo Arnau, AM.; García Gómez, H. (2019). Quality Improvement of Few-Layers Defective Graphene from Biomass and Application for H-2 Generation. Nanomaterials. 9(6):1-15. https://doi.org/10.3390/nano9060895 Bonaccorso, F., Lombardo, A., Hasan, T., Sun, Z., Colombo, L., & Ferrari, A. C. (2012). Production and processing of graphene and 2d crystals. Materials Today, 15(12), 564-589. doi:10.1016/s1369-7021(13)70014-2 Chen, D., Feng, H., & Li, J. (2012). Graphene Oxide: Preparation, Functionalization, and Electrochemical Applications. Chemical Reviews, 112(11), 6027-6053. doi:10.1021/cr300115g Luo, B., Liu, S., & Zhi, L. (2011). Chemical Approaches toward Graphene-Based Nanomaterials and their Applications in Energy-Related Areas. Small, 8(5), 630-646. doi:10.1002/smll.201101396 Machado, B. F., & Serp, P. (2012). Graphene-based materials for catalysis.