Structural and Compositional Changes of Graphene Oxide-Based Nanomaterials during Hydrogen Storage

Abstract

This study explores the hydrogen storage performance of graphene oxide (GO), reduced graphene oxide, and interconnected reduced graphene oxide over a pressure range of 0–50 bar and temperatures of 30, 50, 75, and 100 °C using a gravimetric measurement system. Among those nanomaterials, GO exhibited the highest hydrogen storage capacity of 2.35 wt % at 75 °C and 50 bar. Comprehensive characterization, including electrochemical techniques, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction, was carried out to investigate their structural and compositional transformations before and after hydrogen uptake and release. The results reveal that selective reduction and removal of some of the carbonyl (C=O), epoxy (C–O–C), and hydroxyl (C–OH) groups of GO-based nanomaterials occurred during the hydrogen storage process. The hydrogen storage capacities of GO-based nanomaterials were increased with the increase of temperature, ranging from 30 to 100 °C, likely due to the thermal and pressure-induced realignment and expansion of graphene interlayer spacing. These findings highlight the dynamic nature of GO-based nanomaterials under hydrogen storage conditions and provide some insights into their structural evolution and performance optimization.