Artificial Photosynthesis.

October 2, 2015

Richard Watt

The iron mineral core of ferritin has been characterized as ferrihydrite, hematite and magnetite.  Such minerals possess semi-conductor properties.  The protein shell of ferritin allows these semi-conductors to be soluble in aqueous solutions and provides a unique nano-cage for solution phase photo catalysis.  Ferritin is photo chemically active and can photo-oxidize organic molecules and store the high-energy electrons in the conduction band of the mineral, making a stable electron donor.  Our laboratory has used ferritin to photo-reduce metal cations to form ~10 nm nanoparticles of gold, platinum, palladium and silver.  We are expanding this initial work to study electron donors, photo-catalysts inside ferritin and electron acceptors.  Carboxylates, aldehydes, alcohols, amines and sulfur containing molecules act as electron donors for the ferritin photo-oxidation reaction (source of electrons as fuel).  In addition, we are examining ferritin with different mineral cores as photo-catalysts to determine if they are more efficient catalysts and if they utilize different wavelengths of light.  Active catalysts inside ferritin include metal oxides of Fe, Fe and phosphate, Mn and Co. Finally we have attached ferritin to electrodes and successfully used the electrode as an electron acceptor to store the harvested electrons.  Applications for these photochemical reactions will be discussed.