Light-driven CO₂ reduction in metal-organic frameworks Strategies for catalyst immobilization

The increasing concentration of atmospheric CO₂ due to fossil fuel overreliance demands innovative solutions to mitigate climate change and transition toward a carbon-neutral society. This thesis focuses on the development of a hybrid catalytic platform for photocatalytic CO₂-to-CO reduction, combining the high activity and selectivity of molecular catalysts with the stability and recyclability of heterogeneous systems. In this work, we employed porous, tuneable, and hierarchical coordination polymers, known as Metal-Organic Frameworks (MOFs), to immobilize an active and selective CO₂ reduction molecular catalyst, creating a hybrid material. Initially, the optimal catalyst loading within the MOF was identified to balance porosity and catalytic performance to optimize CO₂-to-CO conversion. The study further explored different installation strategies for the catalyst within the MOF, revealing that the coordination linkage between the catalyst and MOF provides the most robust attachment, minimizing leaching and enhancing long-term stability. Next, a comparative analysis between 3D and 2D assemblies highlighted the trade-off between initial catalytic performance and durability, with MOFs demonstrating superior recyclability. Finally, the hybrid material was integrated into a dye-sensitized photoelectrochemical cell, where a redox mediator facilitated electron transfer from the photoelectrode to the catalytic sites within the MOF. The fabricated device achieved a stable photocurrent, leading to the formation of CO. This work advances the understanding of hybrid catalysts for solar fuels, emphasizing the importance of catalyst loading, immobilization strategy, and integration into functional devices. The findings offer a promising step toward scalable and sustainable artificial photosynthesis..