| dc.description.abstract | To mitigate global warming and climate change, it is an urgent mission for us to reduce the amount of CO2 in the atmosphere. One of the viable solutions to this challenge may be to capture, and preferably, to recover CO2 from gas phases. It has been reported that CO2 gas can be captured and decomposed into elemental carbon and oxygen by molten salt electrolysis. In this study, CO2 splitting in molten CaCl2-NaCl-CaCO3 was explored. Although this CaCl2-based salt system has many advantages such as the low cost and abundance of the materials, there are limited numbers of studies, and the understanding of the process is still insufficient. To provide some insights into it, the following things were investigated. First, the cathodic behaviour of carbonate in the melt was studied. Voltammetric studies revealed that the reduction process was happening in either one step or two steps depending on the electrode materials. The nucleation process of carbon was studied, and the diffusion coefficient of carbonate ion was determined from the current transient. Second, the feasibility of inert anodes in the process was examined. An SnO2-based anode showed a good performance and stability in the present molten salt system for a long time. Finally, voltammetric and electrolytic studies using actual CO2 gas were carried out. Pure or diluted (1 vol%) CO2 gas was injected into the system as the carbon source. In either case, the deposition of carbon on the cathode was confirmed. | |
