PVA based self-supported microporous carbon nanomats for H2 adsorption

ALICIA VERGARA; LAURA RIBBA; DAVID PICÓN; KARIM SAPAG; ROBERTO CANDAL; SILVIA GOYANES

Simposio; VIII Symposium on Hydrogen, Fuel Cells and Advanced Batteries, HYCELTEC 2022; 2022

The successful implementation of hydrogen (H2) as analternative energy source to replace fossil fuels will depend on developing highly efficient H2 storage technologies. Porous carbons are promising materials for this application;when their porous size is between 0.6–0.7 nm in diameter[1], H2 can be absorbed on their surface. One crucial point in developing ultramicroporous carbon materials for H2 storage as clean energy devices is how green the materials andprocesses involved in their development are. Another point to consider is the integrity of these materials, as carbon powders can cause problems associated with the need for a binder that lowers the efficiency of the material. Carbon nanostructures can be obtained from the pyrolysis of polymeric electrospun mats through stabilization and carbonization treatments. The most widely used polymer to generate carbon nanofibers through pyrolysis is polyacrylonitrile (PAN) because its chemical structure leads to high carbon yields. However, this polymer is electrospun from solutions in harmful organic solvents, such as DMF. Other possibility is using polyvinyl alcohol (PVA) which can be easily electrospun using water as solvent and, after stabilizationtreatments. Recently, the possibility of obtaining carbon nanobifrous mats by previously applying only a heat treatment to pristine PVA fibers was demonstrated, but the abrupt stabilization treatment led to a large number of defects on the surface of the carbon fibers [2]. Our group recently proposed a slow and stepped heat treatment that allowed the production of a new and more stable structure of the polyene type, capable of withstand highly concentrated sulfuric acid exposure, from PVA electrospun mats.Herein, we develop a new carbon nanostructure with high H2 storage capacity by the pyrolysis of green electrospun mats obtained from biodegradable PVA aqueous solutions. Before pyrolysis the mats are exposed to a heat stabilization treatment. The obtained carbon material is self-supporting, can be obtained in large scale (at least several cm2) and possess physical integrity, avoiding the problems associated with carbon powders. Thanks to electrospinning technique versatility this work opens a wide range of possibilities for the development of new green porous carb