Palladium-decorated unconventional graphene oxide for unprecedented hydrogen storage

Abstract

Hydrogen storage in solid-state mediums has gained significant attention as it provides high energy density and exhibits improved safety compared to conventional compressed gas or liquefied hydrogen storage. In this work, for the first time, palladium-decorated, highly functionalized reduced graphene oxide is reported for enhanced hydrogen storage at nearly ambient conditions. The concept of using unconventional, highly functionalized graphene oxide (HGO) instead of conventional graphene oxide (GO) is to decorate higher number of Pd nanoparticles on graphene oxide sheets. Pd nanoparticles were decorated on reduced and highly functionalized graphene oxide sheets (Pd-rHGO) through an impregnation approach. The Pd decoration and HGO reduction to rHGO were achieved simultaneously. The morphological and structural characterizations of the rHGO and Pd-rHGO samples were analyzed using XRD, Raman, XPS, SEM, BET, and HRTEM techniques. The optimized Pd-rHGO sample demonstrated an ultrahigh gravimetric hydrogen uptake capacity of 6.62 wt% at nearly ambient conditions with reversibility and excellent retention capacity. This unprecedented hydrogen storage capacity of the Pd-rHGO nanocomposite is due to the strong affinity of the Pd atoms to hydrogen, as they act as a catalysts for hydrogen adsorption. Consequently, hydrogen molecules can adhere to the Pd-rHGO surface more readily, increasing the amount of hydrogen that can be stored. Therefore, the present work aims to help develop efficient and compact hydrogen storage systems, which are crucial for advancing hydrogen-based energy applications.