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Identifier

000434022

Title

Multi scale investigation of hydrogen adsorption in metal-organic frameworks

Alternative Title

Θεωρητική μελέτη προσρόφησης υδρογόνου σε μεταλλο-οργανικά σκελετικά υλικά με μεθόδους πολλαπλής κλίμακος

Author

Γιάππα, Ραφαέλα Μαρία Ι.

Thesis advisor

Φρουδάκης, Γεώργιος

Reviewer

Τρικαλίτης, Παντελής
Στούμπος, Αθανάσιος

Abstract

Nowadays humanity is facing two urgent, interconnected problems; the exhaust of conventional energy resources and the need to reduce CO₂ emissions and move towards a sustainable carbon emission free economy. Within the scope of sustainability, hydrogen economy presents a possible solution to both problems. Hydrogen is a completely clean, non-toxic burning fuel which when consumed in a fuel cell, the only by-product is pure water. Fuel-cell technology is currently under intensive research and development in view of the expected benefits in facing the environmental problems and the gradual depletion of conventional fuel reserves. The main obstacle for the commercial development of fuel-cell powered vehicles is the efficient hydrogen storage. Among the existing technologies, an alternative way of storing hydrogen is the adsorption in porous materials, such as Metal Organic Frameworks (MOFs). Many different strategies have been up-to-date employed to enhance the hydrogen storage capacity of MOFs. Τhe objective in this project is to design new materials that have improved sorption capacities through enhancing their interaction with H₂. Within the scope of the multiscale approach, we investigate in silico the H₂ capacity enhancement in several MOF-type nanomaterials, when these are properly functionalized with a variety of chemical species. Driven by the fact that the organic linkers of most MOFs have aromatic backbones such as benzene, we screen simple aromatic systems of the form C₆H₅X (where X stands for different functional groups) for their binding strength towards hydrogen. Ab initio calculations are employed to calculate the binding energy and favorable positions of hydrogen with a series of strategically selected functionalized benzenes. Subsequently, GCMC calculations with model potentials derived from the ab initio calculations, are employed to study the trend obtained from the meticulous ab initio search. The results from our bottom-up approach lead us to conclude that this functionalization strategy can be applied to various porous materials (MOFs, COFs, etc.), in order to enhance their hydrogen storage performance, especially at cryogenic temperatures.

Language

English

Subject

Ab initio

Fuel-cells

Functionalization

GCMC

Hydrogen storage

MOFs

Multi-scale

Sustainability

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