Living photovoltaics are microbial electrochemical devices that use whole cell–electrode interactions to convert solar energy to electricity. The bottleneck in these technologies is the limited electron transfer between the microbe and the electrode surface. This study focuses on enhancing this transfer by engineering a polydopamine (PDA) coating on the outer membrane of the photosynthetic microbe Synechocystis sp. PCC6803. This coating provides a conductive nanoparticle shell to increase electrode adhesion and improve microbial charge extraction. A combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis absorption, and Raman spectroscopy measurements were used to characterize the nanoparticle shell under various synthesis conditions. The cell viability and activity were further assessed through oxygen evolution, growth curve, and confocal fluorescence microscopy measurements. The results show sustained cell growth and detectable PDA surface coverage under slightly alkaline conditions (pH 7.5) and at low initial dopamine (DA) concentrations (1 mM). The exoelectrogenicity of the cells prepared under these conditions was also characterized through cyclic voltammetry (CV) and chronoamperometry (CA). The measurements show a three-fold enhancement in the photocurrent at an applied bias of 0.3 V (vs. Ag/AgCl [3 M KCl]) compared to non-coated cells. This study thus lays the framework for engineering the next generation of living photovoltaics with improved performances using biosynthetic electrodes.

Microbial fuel cells and biophotovoltaics represent promising technologies for green bioelectricity generation. However, these devices suffer from low durability and efficiency that stem from their reliance on living organisms to act as catalysts. Such limitations can be overcome with augmented capabilities enabled by nanotechnology. This review presents an overview of the different nanomaterials used to enhance bioelectricity generation through improved light harvesting, extracellular electron transfer, and anode performance. The implementation of nanomaterials in whole-cell energy devices holds promise in developing bioelectrical devices that are suitable for industry.