Living Photoanodes for Solar-Driven Water Oxidation

Photosynthetic microorganisms are abundant, self-sustaining catalysts that convert solar energy into high energy electrons. By interfacing these living catalysts with electrodes, these electrons can be harnessed for electricity generation or chemical production in sustainable solar-powered technologies. The development of these so-called living photoanodes is an emerging and highly interdisciplinary field that has progressed substantially in recent years. In this review, we chart these advancements, beginning with our current understanding of the fundamental biology underpinning the key photocatalytic and electron transport processes of oxygenic photosynthetic microorganisms─namely cyanobacteria. We then describe theoretical approaches to estimating the maximum obtainable photocurrent outputs of living photoanodes to gauge their technological potential. Next, we discuss the main strategies employed to attain these values which include genetic engineering, electrode and diffusional/polymeric mediator design. Finally, in the outlook section, we recommend standardized reporting methods to formalize the field and propose future research directions to realize the full potential of this nascent technology.