(29f) Incorporation of Photosystem 1 in Three-Dimensional High Surface Area Electrodes

Photosystem I (PSI) is a membrane-bound protein complex that is used in biohybrid photovoltaic devices due to its almost perfect internal quantum efficiency. Light energy absorbed by the bound chlorophylls is shuttled to the primary reaction center of PSI where charge separation and cross-membrane transport leads to the highest reducing potential in nature. Previous studies have shown that the photoactivity of PSI increases with the amount of protein adsorbed onto the electrode. The current study uses a three-dimensional, high surface area conductive electrode of a graphene foam for PSI incorporation. The three-dimensional electrode (specific surface area of 160 m²/g) provides a much larger PSI/metal interface as compared to planar electrodes. The large quantity of PSI incorporated in the 3D scaffold affords higher photocurrent production compared to that obtainable on flat electrodes. In addition, the 3D electrode enables a much steadier photocurrent due to spherical diffusion while the photocurrent on planar electrodes decays with time as expected for semi-infinite linear diffusion.