Photocatalyzed electron transfer from spinach PSI to metal nanoparticles

An essential step towards eventual assembly of photocatalytic biofuel cells is the establishment of stable electron transfer between biocatalysts and metals. Reaction mixtures containing plastocyanin (PC), sodium ascorbate, and the photosynthetic protein complex photosystem I (PSI) photocatalytically reduced hexachloroplatinate to metallic platinum and then evolved hydrogen. Covalent attachment of PC to PSI increased both the rate of both platinum deposition and hydrogen production. Removal of excess hexachloroplatinate from the PCPSIPt biocatalyst resulted in stabilization of the hydrogen evolution rate, presumably by restriction of the platinum particle size. To further investigate electron transfer to catalytic metal particles, PSI with free or covalently attached PC was loaded on hydrated bacterial cellulose membranes containing catalytically active palladium particles ranging in size from 2 to 20 nm. Illumination of these membranes resulted in stable photocatalyzed hydrogen production during successive light cycles. This is an abstract of a paper presented at the 230th ACS National Meeting (Washington, DC 8/28/2005-9/1/2005).