In this second lecture, the "artificial metallo-enzyme" approach is illustrated specifically by examples of hybrid catalysts for artificial photosynthesis. The aim is to invent new high-performance catalysts for the photodecomposition of water into hydrogen and oxygen, enabling solar energy to be stored in the form of fuels. Perhaps the finest demonstration that it is possible to do this artificially is that developed by Moore and Gusten in 1997 and 1998, when they integrated a synthetic triad, comprising a photosensitizer, between an electron acceptor and an electron donor, into a lipid bilayer and induced a pH gradient by light irradiation to provide the energy required by an ATP synthase. Together, they convert solar energy into chemical energy (ATP).
In recent years, numerous hybrid systems based on photosystem I have been prepared and studied. Combined with platinum particles, hydrogenases or cobaloximes, in the presence of a sacrificial electron donor, photosystem I enables efficient photoreduction of protons to hydrogen. This lecture also discusses the laboratory's plans to develop artificial hydrogenases, combining, for example, heme-removed myoglobin or apo-form heme oxygenase with catalytically active cobalt complexes for hydrogen production. This shows how this type of research can be implemented.
