Crystal Engineering of Robust Metal-Organic Frameworks for Applications in Capture of Carbon Dioxide

Abstract

The atmospheric concentration of carbon dioxide gas (CO2) is of global concern given its continued rise. Burning of fossil fuel has increased since the beginning of the industrial revolution, which then increased the atmospheric CO2 concentration to > 400 ppm from 280 ppm. CO2 has an effect of trapping the sun’s heat, and is believed to be one of the cardinal contributors of global warming. In order to make improvements to the CO2 problem, carbon capture techniques have been proposed. MOFs are porous structures constructed from the coordinative bonding between metal ions and organic linkers or bridging ligands. Thus, having an enormous choices of metal clusters and organic linkers, MOFs possess a wide range of surface area, pore volume and functionality, and this has contributed to the consideration of them being versatile materials for storage, separation, and catalysis, etc. Therefore, there is need to synthesise MOFs which capture CO2 and convert it into useful chemicals such as methanol and formic acid for industrial application. Linker 2,2’-bipyridine-5,5’-dicarboxylic acid and ceric metal salt Ce(NO3)3·6H2O were used in this study. Two MOFs were synthesised by solvothermal method. These were characterised by TGA, PXRD, FTIR, Potentiostat Galvanostat and Gas Sorption. The two MOFs MSU-3 and MSU-4 were thermally and chemically stable. The thermal and chemical stability observed in the MOFs emanated from the presence of the rod secondary building unit, which are linked by the pyridyl carboxylate linker to give three dimensional structures. CO2 adsorption studies of the MOFs revealed a low uptake of the gas in comparison to those MOFs reported literature. MSU-3a and MSU-4a was tested for electroactivity. Also, resistivity was tested using electrical impedance spectroscopy. It was found out that both MOFs had a lower interfacial electron transfer resistance.