Oxidation-Resilient Structural Modifications in Nickel- Functionalized 3D Graphene: Perspectives for Hydrogen Storage Applications

Porous materials represent a versatile solution for several applications. Indeed, the recent development of a new material, named 3D graphene, which combines the exceptional characteristics of graphene with a three-dimensional structure, opens perspectives for applications where a high surface-to-volume ratio is beneficial. Here, we explore the functionalization of 3D graphene with nickel (Ni) nanoparticles (diameter <15 nm) as a strategy to enhance hydrogen storage capabilities and oxidation resilience. Samples have been hydrogenated by supplying molecular or atomic hydrogen, and hydrogen storage performance was assessed through thermal desorption spectroscopy. Optimal sample performance is achieved after annealing at temperatures of 900–950 °C. Sample functionalization with Ni NPs enhances the hydrogen uptake by about 70%. Afterward, oxidation effects were systematically studied by exposing the samples to atmospheric oxygen, followed by further hydrogenation experiments. We observed that the adsorption peak at 350 °C is oxidation-resilient and increases up to 85% compared with before exposure to air. Moreover, the oxidation impact is fully recovered after successive annealing at 900 °C. The morphology and structural properties of the pristine and Ni-functionalized samples were characterized using scanning electron microscopy. Additionally, X-ray photoelectron spectroscopy was employed to analyze the surface chemical composition of the functionalized samples. Our results indicate that Ni functionalization influences both hydrogen adsorption and oxidation behavior, with potential implications for improving the stability of the material, especially for hydrogen storage applications.