Chapter 18: CO₂ Reduction Using Metal Complexes as Photocatalysts

In this chapter, photocatalytic systems for the reduction of carbon dioxide (CO₂) using metal complexes are discussed. To construct efficient photocatalytic CO₂ reduction systems, two functions, i.e., redox photosensitizer and catalyst, are required. Metal complexes displaying visible-light absorption and long lifetimes in the excited states might be suitable for redox photosensitizers and redox-active metal complexes having a labile ligand forming a vacant site to activate CO₂ can possibly be used as catalysts. Simple mixed systems of them photocatalyze the reduction of CO₂. In addition, supramolecular photocatalysts in which they are linked via covalent bonds are also introduced.