Chapter 9: Energy from Photosystem II: Manganese Water Oxidation Catalysts

Photosystem II is a blueprint for the design of water oxidation catalysts for incorporation into photoelectrochemical devices capable of efficient solar hydrogen production. In this chapter, we review ongoing efforts to develop manganese water oxidation catalysts. These catalytic systems embody one or more of the key features observed in the PSII water oxidizing complex – the concentration of high energy oxidation states of multiple manganese centres, the ability to facilitate di-oxygen bridge formation, a dynamic supporting environment that prevents dissociation of the complex, assists in electron and proton removal, and aids coupling to a photoactive charge separation centre – with the most successful examples incorporating most or all of these key features. Promising advances have been made towards achieving solar water oxidation, ranging from the direct coupling of Mn complexes to Ru dyes or TiO₂ to demonstrate successful oxidation of Mn centers, to achieving direct light driven water oxidation by coupling a Nafion supported Mn catalysts to a Ru-dye sensitized TiO₂ electrode, which should stimulate further interesting developments.