Study and development of engineered materials to harvest energy from co2 emissions

Nowadays, Earth is undergoing effects of climate change due to the exponential increase of greenhouse gasses's emissions. The main component of greenhouse emissions is carbon dioxide (CO2), which is estimated responsible for about 60% of global warming generated by human activities, and its concentration is increased by 40% with respect to the concentration at the beginnings of industrial era. This increase is due to several factors such as the combustion of coal, oil and gas and the progressive deforestation: this last phenomenon generates a sort of bottleneck in the so called biogeochemical "carbon cycle". Deforestation causes the lack of one of the natural regulating sources of carbon dioxide concentration. Scientists set an increase of 2°C (with respect to the pre-industrial global temperature) as the threshold beyond which there is a much higher risk that dangerous and possibly catastrophic changes in the global environment will occur. Nowadays the increase of temperature has reached about +0,85°C thanks to greenhouse gasses. All technologies developed in CO2 capturing have to be intended in the reduction of global warming. In this thesis the goal is to develop a device able to harvest energy from carbon dioxide harvesting, exploiting graphene based supercapacitors and both aqueous solutions and ionic liquids as electrolytes. The intent of the device is to cutting down greenhouse emissions by reusing human produced carbon dioxide. Strategy to apply is capacitive mixing, which was a concept firstly applied to energy harvesting from salinity gradients: flowing through a capacitor (in which electrodes are modified using ion exchange membranes) alternatively salty water and fresh water, we modify the electrical double layer at the electrode-electrolyte interface. Ion exchange membranes allow the selective accumulation of opposite sign ions on the opposite electrodes. In this way it is possible to generate a DC power. Since there is no technology able to harvest mixing energy from gas sources, the idea was to adapt capmix in order to do so: we alternatively flush inside the electrolyte in an ion exchange membrane modified super-capacitor firstly CO2, then N2. In this way we have no more a salinity gradient, but a gradient in CO2 concentration. The idea is to exploit the conducibility reaction linked to adsorption carbon dioxide in a certain electrolyte in order to harvest energy in a similar way to one developed in capacitive mixing.