Functionalisation of 3D Graphene with Nickel Nanoparticles: Oxidation-resilient structural modifications for increased solid-state hydrogen storage

We employ Nickel nanoparticles (Ni NPs) to functionalize 3D Graphene and to enhance its hydrogen uptake. This is a key point to employ the material in solid-state hydrogen storage. Our findings show improvement in the resilience of storage performance to oxidation effects. The 3D Graphene samples were obtained by thermal decomposition of porousified SiC in ultra-high vacuum. The morphology of the samples was investigated by Scanning Electron Microscopy (SEM). Raman spectroscopy was employed to evaluate graphene quality and crystallinity. Ni NPs were synthesized with a rapid and efficient process and used to functionalize the samples via colloidal suspension. The effectiveness of functionalization was verified via SEM imaging. Raman spectroscopy was used to assess the impact of functionalization on graphene quality. X-Ray Photoelectron Spectroscopy was performed on functionalized samples, to evaluate the chemical composition and changes during heat treatments. To evaluate the hydrogen storage performance of the samples, Thermal Desorption Spectroscopy (TDS) was performed after molecular or atomic hydrogen exposure, comparing pristine and functionalized samples. In addition, samples were exposed to atmospheric oxygen, and a hydrogenation experiment was repeated to assess the change in performance due to oxidative processes. We show that the 3D Graphene effectively protects the Ni NPs from oxidation, while at the same time maintaining the hydrogen storage performance.