Detailed microstructural analysis and hydrogenation performance of ball-milled nanocrystalline MgH2 powders co-catalyzed by FeTiH2 and GO

High-energy ball-milling technique was employed to synthesize a series of MgH 2 – based composite powders containing 30 wt.% Fe – TiH 2 milled solution as a catalyst and graphene oxide as a co-catalyst. Milling durations of 1 h, 3 h and 10 h were investigated. The morphology of the as-milled powders was examined by scanning electron microscopy and transmitting electron microscopy, while their microstructural characteristics were analyzed by X-ray diffraction. Convolutional Multiple Whole Profile fitting algorithm was applied to quantify the microstructural parameters of the powders. Prolonged milling time resulted in a pronounced reduction in powder aggregate size, accompanied by a decrease in the coherently scattering crystallite size to approximately 7 nm. Concurrently, severe plastic deformation induced a very high dislocation density (~10 16 nm -2 ). The dehydrogenation behavior of the composites was studied by differential scanning calorimetry, revealing that the addition of graphene oxide significantly lowers the hydrogen desorption temperatures. Hydrogen sorption kinetics measured using a Sieverts-type apparatus demonstrated that the composite milled for 3 h exhibits the most rapid hydrogen absorption and desorption behavior. • Nanocrystalline MgH 2 + FeTiH/GO composites were prepared by high energy ball milling • FeTi catalyst can be embedded in hydride aggregates forming a core-shell structure • According to CMWP analysis the powders exhibit a fine nanocrystalline structure • FeTiH+GO catalyst leads to a significant decrease in desorption temperature of MgH 2 • Dehydrogenation after a complete H-cycle does not degrade the nanocstructure