Boosting electricity generation in biophotovoltaics through nanomaterials targeting specific cellular locations

Photosynthetic microorganisms have been utilized to convert solar energy into electricity, a technology known as biophotovoltaics (BPV), due to their environmentally-friendly characteristics. BPV technology relies on two cellular processes of photosynthetic microorganisms, i.e. intracellular photosynthesis and extracellular electron transfer (EET). The low EET efficiency of photosynthetic microorganisms has been identified as the main bottleneck of BPV systems. In recent decades, various attempts have been made to improve the power output of BPV systems. Among these, coupling nanomaterials with photosynthetic cells has emerged as an effective approach for enhancing electron transfer towards extracellular electrodes. This review summarizes recent advances in photosynthetic-nanomaterial hybrid systems and underscores the respective roles of nanomaterials distributed in different cellular locations. The EET sub-processes, encompassing intracellular electron transfer, transmembrane electron transfer and interfacial electron transfer, can be facilitated by the nanomaterials situated in intracellular space, cell envelope, and cell-electrode interface, respectively. Furthermore, the approaches utilized to target nanomaterials into various cellular structures are discussed. Finally, several potential strategies for the rational engineering of photosynthetic-nanomaterial hybrids with specific cellular locations were proposed.