A light-driven photosynthetic microbial fuel cell for carbon-negative bioelectricity production

Abstract

Microbial fuel cells (MFCs) can convert chemical energy into electrical energy directly through the decomposition of organic matter by electroactive bacteria (EAB). In this process, many research groups have investigated MFCs under dark conditions, but few studies have examined those operated under light conditions. This study compared the photosynthetic MFC under light conditions (P-MFC) and MFC under dark conditions (D-MFC) for bioelectricity production and power density. The electroactive photosynthetic microbial community was enriched in the anode chamber of P-MFC. The acetate consumption and COD removal rate of the P-MFC were two times faster than that of D-MFC. The volume of effluent biogas (e.g., CO₂ and CH₄) from the decomposition of organic matter in the P-MFC was significantly lower than that from the D-MFC. Under light conditions, the electroactive photosynthetic microbial community assimilates the CO₂ produced by organic decomposition. Field emission scanning electron microscopy of P-MFC revealed aggregated electroactive cells with a fibrous appendage on the carbon surface. P-MFC also revealed a higher maximum power density (836 mW m⁻²) than D-MFC (592 mW m⁻²). This study provides a new concept for photosynthetic microbial fuel cells for bioelectricity production without CO₂ emissions.