Hydrogen storage performance and microstructure of ball-milled MgH2 catalyzed by FeTiH2, GO and rGO

A series of MgH 2 –based composite powders was synthesized via high-energy ball-milling. Pre-milled Fe–TiH 2 was introduced into MgH 2 and further co-catalyzed with graphene oxide and reduced graphene oxide with a fixed milling duration of 3 h. The morphology of the milled powders was characterized by scanning electron microscopy and transmission electron microscopy, while the microstructural features were analyzed by X-ray diffraction. Quantitative microstructural parameters were obtained using the Convolutional Multiple Whole Profile fitting method. All powders consist of fine nanometer-scale crystalline domains (⟨D⟩ area ∼7 nm) and exhibit very large high dislocation density ( ρ ∼10 16 m −2 ), when FeTiH + rGO or FeTiH + GO are co-milled with MgH 2 . Dehydrogenation behavior was analyzed by differential scanning calorimetry), while hydrogen sorption kinetics were evaluated using a Sieverts-type apparatus. The results indicate that graphene oxide acts not only as a cost-effective mechanical alternative to reduced graphene oxide but also as an efficient catalytic promoter that enhances the performance of metallic additives in MgH 2 -based hydrogen storage systems.