Photocatalytic Carbon Dioxide Reduction with Ionic Liquids

Abstract

This thesis explores the photocatalytic reduction of CO2 to CO, a key intermediate in chemical production, with a focus on the role of imidazolium-based ionic liquids (ILs) in enhancing performance.Imidazolium-based ILs will be studied for their ability to promote CO2 activation and improve photocatalytic efficiency, particularly through their anion basicity and cooperative interactions with CO2. Homogeneous systems using ruthenium-based photosensitizers and rhenium catalysts serve as benchmark systems for selective CO2 reduction to CO in combination with ionic liquids.To address stability challenges, efforts are directed toward immobilizing photocatalytic components within polymerized ionic liquid matrices. Functionalized photosensitizers, catalysts, and IL monomers will be co-polymerized to create heterogeneous systems, which improve long-term stability and enable the development of robust photocatalytic systems. Mechanistic studies will be conducted to confirm electron transfer pathways and ensure catalyst integrity under reaction conditions.In addition, the incorporation of imidazolium groups into porous materials, such as metal-organic frameworks (MOFs), will be explored as a promising strategy to transfer CO2-activating properties to highly structured and stable materials. Gas-phase reactor systems will be also developed to facilitate gas-phase reactions. These setups allow for catalyst testing under both batch and flow conditions, supporting the scale-up of advanced heterogeneous materials such as supported ionic liquid phases (SILPs) and photoactive g-CN-based supports. These advancements aim to enhance the efficiency, stability, and scalability of CO2 reduction technologies for practical applications.