Photocatalytic Carbon Dioxide Reduction with Imidazolium-Based Ionic Liquids

The growing urgency of addressing climate change caused by greenhouse gas emissions and dwindling fossil fuel supplies has heightened the need for effective strategies to capture and utilize carbon dioxide. Photocatalytic CO₂ conversion, inspired by natural photosynthesis, presents a viable approach for transforming CO₂ into useful C₁-C₃ chemical intermediates for industrial purposes. However, the inherent stability of CO₂ and the competing hydrogen evolution reaction (HER) introduce significant obstacles. Imidazolium-based ionic liquids can pre-activate CO₂, accelerate reaction kinetics, and act as eco-friendly solvents or additives. Systems employing ionic liquids with catalysts, such as homogeneous organocatalysts and heterogeneous materials like Metal-Organic Frameworks (MOFs) and quantum dots, offer potential solutions to these challenges. This review focuses on the role of ionic liquids in both homogeneous and heterogeneous photocatalytic processes, emphasizing their use in CO₂ reduction and highlighting recent mechanistic insights for imidazolium-based species.