Construction of novel cyanobacteria-based biological photovoltaic solar cells: Hydrogen and photocurrent generated via both photosynthesis and respiratory system

Biological photovoltaic (BPV) cells use biological organisms in order to produce clean electrical power by capturing solar energy. In this study, a cyanobacteria based BPV cell was constructed and it generated H2 gas and photocurrent via photosynthesis and respiratory system. This kind of BPV cell was constructed in which the cathode and photoanode are gold electrodes coated with different conjugated polymers and these polymers are combined to Pt or Au nanoparticles with oligoaniline bonds. Unlike the cathode electrode, a kind of cyano-bacteria (Leptolyngbia sp.) was used in the design of photoanode and bounded to Au NPs with oligoaniline bonds. For the configuration of cathode in BPV cell, a gold electrode was first coated with a dithienylpyrrole-based conductive polymer with an amine open-ended aniline functional group. This conductive polymer was then attached to mercapto-aniline functionalized Pt nanoparticles with oligoaniline bonds. In the case of pho-toanode in BPV cell, this time, a dithienopyrrole-based conductive polymer with an aniline subunit was coated on another Au electrode surface via electrochemical polymerization. This polymer provides to connect oligoaniline modified Au nanoparticles with coating cyanobacteria. Some control and optimization experiments for photo-anode of the system were done in order to understand photosynthesis formation and get efficient photocurrent from BPV cell. The system was illuminated under visible light and a constant potential and then the decom-position of water in BPV solar cell system was observed via photosynthesis by cyanobacteria with the formation of H2 and O2 gases besides photocurrent generation. Another photocurrent generation via respiratory system of cyanaobacteria was also investigated in the medium of glucose after diuron (PS II inhibitor an inhibitor) was added into medium. By using two different properties (photosynthesis and respiratory system) of cyanobacteria, BPV solar system generates high amount of photocurrent and hydrogen.