Bioelectrocatalysis is an interdisciplinary research field combining biocatalysis and electrocatalysis via the utilization of materials derived from biological systems as catalysts to catalyze the redox reactions occurring at an electrode. Bioelectrocatalysis synergistically couples the merits of both biocatalysis and electrocatalysis. The advantages of biocatalysis include high activity, high selectivity, wide substrate scope, and mild reaction conditions. The advantages of electrocatalysis include the possible utilization of renewable electricity as an electron source and high energy conversion efficiency. These properties are integrated to achieve selective biosensing, efficient energy conversion, and the production of diverse products. This review seeks to systematically and comprehensively detail the fundamentals, analyze the existing problems, summarize the development status and applications, and look toward the future development directions of bioelectrocatalysis. First, the structure, function, and modification of bioelectrocatalysts are discussed. Second, the essentials of bioelectrocatalytic systems, including electron transfer mechanisms, electrode materials, and reaction medium, are described. Third, the application of bioelectrocatalysis in the fields of biosensors, fuel cells, solar cells, catalytic mechanism studies, and bioelectrosyntheses of high-value chemicals are systematically summarized. Finally, future developments and a perspective on bioelectrocatalysis are suggested.

Establishing an efficient extracellular electron transfer (EET) process between photoelectroactive microorganisms and an electrode surface is critical for the development of photobioelectrocatalysis. Soluble and immobilized redox mediators have been applied with the purple bacterium Rhodobacter capsulatus for this purpose. However, detailed information on its EET with an electrode surface is not available and, therefore, choice of mediators has been by trial and error. Herein, we experimentally evaluated the capability of different soluble, quinone-based redox mediators to support EET and compared the experimental data with a computational model based on density functional theory calculations. We show that computed electrochemical redox properties of redox mediators in a lipophilic environment correlate to EET processes of Rhodobacter capsulatus, suggesting that intermembrane mediator characteristics are more diagnostic than redox properties of the mediators in an aqueous solution, and that the limiting electron transfer step takes place in the lipophilic membrane of the bacterial cells. This knowledge provides critical insight into designing future mediated bioelectrocatalysis systems.

The ability to establish successful and efficient extracellular electron transfer (EET) between bacteria and electrode surfaces is critical for the development of mediated microbial electrochemical technologies. Here, we describe a phenazine-based mediator system to facilitate electron transfer from the model bacterium Escherichia coli during glucose metabolism. Phenazine redox mediators were experimentally evaluated, demonstrating distinct mediated currents, dependent on mediator structure. Our results show that the choice of a mediator with the appropriate redox potential is not the single aspect to consider when rationally designing future mediator-based EET systems.

Combination of electrochemical methods, quantum mechanical calculations, bioinformatics, and bioengineering allows understanding the photoexcited electron transfer process and set the basis for artificially tuning photo-bioelectrocatalysis.