Harvesting photocurrents from cyanobacteria and algae

Photosynthetic microorganisms such as cyanobacteria and algae engage in extracellular electron transport, secreting electrons derived from photosynthesis to the cell exterior. This process can be drastically enhanced towards the development of novel biotechnologies for clean energy production, but it is still underperforming by orders of magnitude compared to theoretical limits. Research in this area is improving photocurrent outputs through genetic engineering, the addition of redox- and conductive-polymers, the use of diffusional redox mediators, electrode design, and expanding the selection of microorganisms used to generate photocurrents. This review covers the most promising research from the last two years that has sought to understand the mechanisms of photocurrent generation and increase the magnitude of photocurrent outputs. Areas of research that showed the most progress recently include those that interrogate the biotic–abiotic interface and those that take a generalised approach to testing the contributions of cells, electrodes, polymers, and mediators systematically under standardised conditions.