Environmental impact of the production of graphene oxide and reduced graphene oxide

1 Tabla, 5 Figuras.-- Material suplementario disponible en línea en la página web del editor.Reduced graphene oxide (rGO) is widely seen as the most promising route for the low-cost mass production of graphene for many applications ranging from ultrathin electrodes to structural nanocomposites. The Hummers and Marcano methods are the two most successful approaches for producing high-performance rGO, but have been criticized for producing toxic emissions. We have applied life cycle assessment methodology to evaluate the environmental impacts of both production routes for GO and rGO in the context of applications requiring bulk materials or thin coatings. We find no current obstacle to the industrial scale production of graphene arising from its environmental impact. The cumulative energy demand is found to have a cap value between 20.7 and 68.5 GJ/Kg, a relatively high value; impact in other categories (such as human toxicity or resource depletion) is lower, and materials inventory does not include critical/strategic materials other than graphite itself. Our study proposes 1 kg of graphene as functional unit, and an application-specific functional unit normalized by conductivity which show that Hummers production method is far more suitable for bulk applications of graphene, with lower embedded energy per kg of graphene production, while Marcano’s production method is better suited for thin film electronic applications.This work was supported by Projects ENE2016-79282-C5-1-R and ENE2016-79282-C5-5-R funded by MINECO-Spain (including EU FEDER funds), Project 19882-GERM-15 funded by F. Séneca (Región de Murcia, Spain), and DGA Grupo Reconocido T03_17R by Gobierno de Aragón (including EU FEDER funds). L. S.-L. and C. T. are also grateful to F. Séneca for postdoctoral grant Ref. 19759/PD/15, and predoctoral grant Ref.19768/FPI/15 respectively. SVR thanks Spanish MINECO for her PhD grant (BES2014-068727 and associated EU Social Funds).Peer reviewe