Environmentally benign biophotovoltaic cell using thylakoid membrane and graphene–cellulose nanocomposite for solar energy harvesting and photoelectrochemical monitoring of waterborne herbicides

This study explores the potential of biophotovoltaic devices (BPVs) as sustainable solutions to global energy and environmental challenges. Utilizing biocomponents such as chlorophylls, green algae and cyanobacteria, BPVs convert sunlight into renewable energy via photosynthesis. Carbon-based electrodes, particularly graphene, have gained attention due to their affordability, superior electrical conductivity, and mechanical stability. While reduced graphene oxide is commonly employed, recent research highlights the superior current-harvesting properties of non-oxidized graphene, warranting further investigation. Additionally, one-dimensional nanomaterials like electrospun nanofibers present promising opportunities to enhance charge collection and electron transfer efficiency. In this context, a novel photoanode was designed, integrating thylakoid membranes immobilized on a graphene-cellulose acetate electrospun nanofiber matrix, fostering effective cyanobacterial adhesion and electron transfer. The cathode employed a gold electrode coated with P(DTP-NH₂) via electrochemical deposition, subsequently functionalized with bilirubin oxidase using glutaraldehyde activation. The system achieved a peak power density of 56.2 mW/m² and a stable current density of 100 mA/m². Beyond electricity generation, the BPV demonstrated herbicide biosensing capabilities, detecting atrazine with a detection range of 0.1–1.2 μM and a detection limit of 9.2 nM. Recovery studies confirmed the system's reliability as a biosensor, underscoring its dual functionality in renewable energy generation and environmental monitoring.