METAL ORGANIC FRAMEWORKS WITH SPECIAL TOPOLOGY AND OPEN METAL SITES FOR IMPROVED HYDROGEN ADSORPTION

Abstract

Hydrogen is a promising candidate as a replacement of fossil fuels due to its zero-carbon emission upon combustion. Storage of hydrogen is one of the most important technical challenges especially for on-board applications because of its low density. Along with many other candidates such as chemical storage materials like hybrid metal hydrides and physical storage candidates like zeolites, hydrogen storage in metal organic frameworks (MOFs) has been studied extensively for the last two decades for their high potential to be used in on-board storage applications. One of the promising MOF materials is PCN-12 due to having open copper sites which enhances interactions with the hydrogen and its unique topology which maximizes the interactions further. Although PCN-12 shows great potential, it has not received enough attention mainly due to technical challenges during its synthesis which would require usage of sealed pyrex tubes and gradual temperature changes over a day. In this study, we have demonstrated a facile solvothermal synthesis method for PCN-12 with high yield (79% based on ligand) and high crystallinity by adding an optimized amount of nitric acid to the solution of the ligand and metal salt. We have also investigated the effect of nitric acid amount on crystal formation and adsorptive properties of PCN-12. Furthermore, we have attempted to synthesize new MOF structures based on PCN-12 in order to investigate their hydrogen storage properties.