Synergistic integration of nickel, porous silicon, and thermally reduced graphene oxide for solid-state hydrogen energy storage

Abstract

Solid-state hydrogen storage using metal hydrides offers the potential for high energy storage capacities. However, the requirement for high-temperature operations (above 400°C) and challenges with heat exchange are significant drawbacks. From this perspective, adsorption on porous materials presents a viable solution to these challenges. Carbon nanostructures, such as graphene and graphene oxide (GO) derivatives, are well-suited for hydrogen storage because of their lightweight nature, low density, and large surface area. However, the primary obstacle for practical applications is the poor storage capacity of carbon nanostructures under ambient conditions. Utilizing a cost-effective transition element such as nickel as a catalyst offers significant potential for storing hydrogen in atomic and molecular forms by invoking the spillover mechanism. Thermally reduced graphene oxide (TrGO) modifies the surface, providing abundant active sites that attract hydrogen effectively. Porous silicon (PS) enhances the surface properties of graphene sheets, attracting hydrogen to the surface. The current study assesses a synthesized TrGO, PS, and Ni composition to leverage their individual properties for hydrogen storage. Field-emission scanning electron microscopy examines the sheet structure of TrGO (used as the host material) and the incorporation of PS and Ni on its surface. The calculated specific surface area of TrGO is ~450 m² g⁻¹. X-ray diffraction is used to identify the various phases in the composition, while Raman spectroscopy measures the degree of disorder within the composition. The pressure-composition isotherms reveal hydrogen storage capacities of ~6.53 wt% for the TrGO + PS composition and ~2.43 wt% for the TrGO + PS + Ni composition. Despite the decrease in weight percentage of TrGO + PS + Ni due to the higher Ni content, dissociation enhances the adsorption rate from 0.35 to 0.53 wt% h⁻¹.