Enhanced hydrogen storage kinetics and air stability of nanoconfined NaAlH4 in graphene oxide framework

Abstract

With a growing concern over climate change, hydrogen offers a wide range of opportunities for decarbonization and provides a flexibility in overall energy systems. While hydrogen energy is already plugged into industrial sectors, a physical hydrogen storage system poses a formidable challenge, giving momentum for safe and efficient solid-state hydrogen storage. Accommodating such demands, sodium alanate (NaAlH4) has been considered one of the candidate materials due to its high storage capacity. However, it requires a high temperature for hydrogen desorption and becomes inactive irreversibly upon air-exposure. To enhance sluggish reaction kinetics and reduce the hydrogen desorption temperature, NaAlH4 can be confined into a porous nanoscaffold; however, nanoconfined NaAlH4 with sufficient hydrogen storage performance and competent stability has not been demonstrated so far. In this work, we demonstrate a simultaneously enhanced hydrogen storage performance and air-stability for NaAlH4 particles confined in a nanoporous graphene oxide framework (GOF). The structure of the GOF was elaborately optimized as a nanoscaffold, and NaAlH4 was infiltrated into the pores of the GOF via incipient wetness impregnation. As a result of the nanoconfinement, both the onset temperature and activation energy for hydrogen desorption of NaAlH4 are significantly decreased without transition metal catalysts, while simultaneously achieving the stability under ambient conditions.