Addressing CO2 Electrolysis Challenges with Novel Ion-exchange Membranes

Abstract

As a response to climate change, substantial efforts are being made to achieve global net-zero greenhouse gas emissions by the year of 2050, as established by the Paris agreement. To decrease reliance on fossil fuels, we are transitioning to renewable energies and electrifying various sectors. However, certain segments of the global supply chain will still require carbon-based chemicals and energy carriers. CO2 electrolysis allows the use renewable electricity to electrochemically reduce air-captured CO2, producing chemical building blocks such as CO, ethylene and formate. These chemicals can then be converted into larger hydrocarbons, e.g. into synthetic diesel using the Fischer-Tropsch process. In this way, CO2 electrolysis can aid in closing the carbon cycle by converting CO2 emissions into valuable chemicals and fuels. Despite its promise, a few hurdles still hamper the industrialization of CO2 electrolysis. These are the relatively low energy efficiency, salt deposition, the inefficient use of CO2 due to carbonate cross-over and the necessity of scarce iridium-based anode catalysts. Most of the mentioned challenges can potentially be solved by novel, or optimized ionexchange membranes (IEMs) - these have a pivotal role in the process since they provide a conductive medium to selectively transport ions between the electrodes. Increasing the IEM’s ionic conductivity and permselectivity can increase the energy efficiency of the process and decrease cation cross-over and therefore salt deposition. Furthermore, an OH– selective membrane which rejects other anions such as carbonate, can potentially solve the carbonate-cross over issue. In this way, the goal of this work is to develop novel IEMs to address each of the challenges tied with CO2 electrolysis...