No abstract

Metal-organic frameworks (MOF) have emerged as a promising material for green engineering applications due to their attractive properties. But the successful implementation of this material in the field of fuel cell technologies is still a challenge. Researchers have reported more than 50% reduction in experimental bulk density of compacted MOFs relatively to their theoretical crystal density. This has resulted in reduction of gravimetric and volumetric H 2 storage capacities of MOFs. Significant experimental research should be directed toward the consolidation of MOFs to meet (6.5 wt%; 50 g/L) 2025 DoE target for onboard H 2 storage systems. We present an overview of green engineering materials for hydrogen storage systems. The review also summarizes recent advancement in the consolidation of MOFs as absorbents for hydrogen storage. The influence of densification techniques on MOFs textural properties, mechanical stability were discussed. Hydrogen storage capacity of both powder and densified high-performance MOFs were presented.

In this work, glasses within the borosilicate borophosphate and phosphate family were sintered into 3D porous scaffolds using 60 and 70 vol. % NH4(HCO3) as a foaming agent. All scaffolds produced remained amorphous; apart from one third of the glasses which crystallized. All produced scaffolds had porosity >50% and interconnected pores in the range of 250–570 µm; as evidenced by µCT. The in-vitro dissolution of the scaffolds in SBF and changes in compression were assessed as a function of immersion time. The pH of the solution containing the borosilicate scaffolds increased due to the typical non-congruent dissolution of this glass family. Borophosphate and phosphate scaffolds induced a decrease in pH upon dissolution attributed to the congruent dissolution of those materials and the large release of phosphate within the media. As prepared, scaffolds showed compressive strength of 1.29 ± 0.21, 1.56 ± 0.63, 3.63 ± 0.69 MPa for the borosilicate, borophosphate and phosphate samples sintered with 60 vol. % NH4 (HCO3), respectively. Evidence of hydroxyapatite precipitation on the borosilicate glass scaffolds was shown by SEM/EDS, XRD and ICP-OES analysis. The borophosphate scaffolds remained stable upon dissolution. The phosphate scaffolds were fully crystallized, leading to very large release of phosphate in the media.

No abstract

No abstract