Generation of Photocurrents by Bis-aniline-Cross-Linked Pt Nanoparticle/Photosystem I Composites on Electrodes

Pt nanocrystals are implanted into photosystem I (PSI) by a photochemical reaction The PSI with the associated Pt nanoclusters was modified with thioaniline and electropolymerized with thioaniline-functionalized Pt nanoparticles (NPs) to yield a bis-aniline-cross-linked PSI/Pt NPs composite The alignment of the PSI with respect to the Pt NPs leads to effective charge separation and to generation of a photocurrent, phi (lambda = 420 nm) = 2 6%, IPCE similar to 0 35% The bis-aniline units cross-linking the PSI/Pt NPs composite exhibit quasireversible redox features (E(0)' = 0 05 V vs Ag/AgCl, at pH = 7 4) Biasing the electrode potential, E > 0 1 V vs SCE, results in the formation of the oxidized quinoid bis-aniline state that acts as an electron acceptor At this applied potential, the bridges mediate the electron transfer to the electrode, resulting in a similar to 10-fold higher photocurrent, as compared to the system that includes the reduced bis-aniline bridging units Furthermore, the ferredoxin (Fd) electron relay was modified with thioaniline units and Incorporated into the PSI/Pt NP composite during the electropolymerization process The Fd bound to the matrix mediates the electron transfer toward the electrode and facilitates charge separation that results in enhanced generation of the photocurrent, phi (lambda = 420 nm) = 3 8% IPCE similar to 0 5%