Algal Biophotovoltaic Devices: Surface Potential Studies

The exploitation of renewable energy sources for delivering carbon-neutral or carbon-negative solutions has been accomplished through the strategies involving the removal of CO2 from the atmosphere. Algae-fuel is deemed to play a major role in this emerging carbon-negative market via the bioelectricity generation using biophotovoltaic (BPV) cells. Accordingly, we investigate the bioelectricity generation of a freshwater green alga strain from Japan, Chlorella vulgaris (NIES-642), using carbon paper and indium-tin-oxide (ITO) electrodes. The ITO equipped BPV demonstrates the maximum power output of 0.25 mW m(-2), which is remarkably higher than carbon-paper-based BPV (0.21 mW m(-2),). The surface potential studies were conducted to understand the electron transfer at the interface of algal biofilm and electrodes using the Kelvin probe method. The minimal surface potential difference (0.2 V) observed for ITO compared to those of other processed electrodes demonstrates the maximum BPV power generation, owing to its lower electrical resistivity and higher electron donor/acceptor capacity.