Bioinspired water oxidation catalysts for solar hydrogen production

One of the challenges for tlie solar hydrogen production is the development of efficient catalyst, made from earth abundant el ments which can be integrated into light-harvesting photochemical devices. The only natural system established to photooxidise water using visible light .is a catalytic core consisting of a CaMn.Ox cluster known as the water oxidation centre (WOC) of Photosystem II, and is thus an inspiration for catalyst design. Recently, we reported the photon assisted electro-oxidation of water using tetranuclear Mn-oxo cluster ([Mn404L6t, L=(MeOPhhPOi), inspired by the WOC. Efficient electro-oxidation of water was achieved at a potential of 1.2 V (vs SHE) on incorporation within electrode bound Nafion membranes and irradiation with visible Ught. The present article summarises the progress we have made on photo-electrochemical cells that utilise catalysts based on the earth abundant manganese. Solar water oxidation has been achieved in a single multilayer device, combining the water oxidation catalyst with light absorbing dyes, and in tandem devices in which catalytic water electrolysis is driven by photo-voltaic cells, specifically two dye sensitised solar cells.