Bio-inspired constructs for sustainable energy production and use

Sustainable energy production for human use based upon solar powered bio-inspired constructs and renewable resources is achievable. However, several challenges must be overcome before this goal is realized. One is the efficient coupling of electromotive force to the oxidation of water and to the electroreductive synthesis of chemical fuels for energy storage. Beginning with the electrolysis of efficient use of solar energy requires water oxidation at minimal overpotential, a feat accomplished by enzymes found in Nature. However, in order to be used in this context, these enzymes must be switched from their usual source of oxidation potential to other forms such as electromotive force in a metallic conductor. Biological catalysts can use the electrons produced by such oxidations to carry out the synthesis of energy-rich reduced carbon compounds (or hydrogen) with little overpotential and almost no side reactions. But once again, to accomplish this technologically, it will be necessary to switch Nature's catalysts from their usual source of reduction potential to electromotive force in a metallic conductor or other forms of reduction potential. In an initial step in this direction, this article presents a hybrid system in which a porphyrin-sensitized Grätzel-type nanoparticulate wide band gap semiconductor photoanode is used for the photochemical reformation of biomass to hydrogen.