Photosensitisers for CO₂ photoreduction: from metal complexes to rylenes, an overview

Photocatalytic systems for CO₂ reduction represent one of the most important topics within the field of solar fuels. Over last four decades, a great deal of effort has been dedicated to designing such systems, understanding their mechanisms and optimising their components. Together with the more traditional metal complexes, rylenes have recently attracted attention as potential coupled sensitisers for CO₂ photoreduction. This chapter provides an overview on the principles of photocatalysis and CO₂ photoreduction, with a particular attention to the role and design of the photosensitiser. In addition, we discuss in depth the few examples of rhenium–rylene complexes reported in the literature that explore the current limits of these systems and which could be winning strategies to integrate rylenes in a chromophore–catalyst assembly for photo- or photoelectrochemical CO₂ reduction.