Photoelectrochemical Communication between Thylakoid Membranes and Gold Electrodes through Different Quinone Derivatives

Photosynthesis is a sustainable process for the conversion of light energy into chemical energy. Thylakoids in energy-transducing photosynthetic membranes are unique in biological membranes because of their distinguished structure and composition. The quantum trapping efficiency of thylakoid membranes is appealing in photobioelectrochemical research. In this study, thylakoid membranes extracted from spinach are shown to communicate with a gold-nanoparticle-modified solid gold electrode (AuNP-Au) through a series of quinone derivatives. Among these, para-benzoquinone (PBQ) is found to be the best soluble electron-transfer mediator, generating the highest photocurrent of approximately 130 mu Acm(-2) from water oxidation under illumination. In addition, the photocurrent density is investigated as a function of applied potential, the effect of light intensity, quinone concentration, and amount of thylakoid membrane. Finally, the source of photocurrent is confirmed by using 3-(3,4-dichlorophenyl)-1,1-dimethylurea (known by its trade name, Diuron), an inhibitor of photosystem II, which decreases the total photocurrent by 50%.