Molecular water-oxidation catalysts for photoelectrochemical cells

摘要

Photoelectrochemical cells that efficiently split water into oxygen and hydrogen, "the fuel of the future",need to combine robust water oxidation catalysts at the anode (2H_2O→O_2+ 4H~++ 4e~-) with hydrogenreduction catalysts at the cathode (2H~+ + 2e~- →H_2). Both sets of catalysts will, ideally, operate at lowoverpotentials and employ light-driven or light-assisted processes. In this Perspective article, we focuson significant efforts to develop solid state materials and molecular coordination complexes as catalystfor water oxidation. We briefly review the field with emphasis on the various molecular catalysts thathave been developed and then examine the activity of molecular catalysts in water oxidation followingtheir attachment to conducting electrodes. For such molecular species to be useful in a solarwater-splitting device it is preferable that they are securely and durably affixed to an electrode surface.We also consider recent developments aimed at combining the action of molecular catalysts with lightabsorption so that light driven water oxidation may be achieved.