Manipulating photosynthesis for energy conversion in an electrochemical cell
Calkins, Jessica Ong
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With the constant strain on the environment by fossil fuels, finding an alternate source of renewable energy is vital. Among a myriad of renewable energy sources, solar stands out. As of today, solar energy panels operate at ~15 % conversion efficiency. Alternate means of harvesting energy from sunlight is critical for maximum utilization of this ‘free’ energy source. In plant photosynthesis, the quantum efficiency of light conversion is nearly 100 %.1 Photosynthetic membranes inside plant cells use light energy to generate charge separation. The process can be manipulated to generate electrical power in an electrochemical cell. The process uses light and water to produce electricity. In this study, thylakoids extracted from spinach leaves were explored as photo-biological catalysts for light induced water oxidation reaction on an electrode surface. The extracted thylakoids were immobilized onto multi-walled carbon nanotubes (MWNTs) modified gold electrode using a molecular tethering agent2. The resulting thylakoid-MWNT composite electrodes were used as anode in a photo-electrochemical cell to study light driven electricity generation. The steady state current density generated by the system was 22 µA cm-2. This is the first attempt to demonstrate a direct light to electricity conversion in a photosynthetic electrochemical cell using plant thylakoids as photo-biological catalysts.