Sustainable Electron Shuttling Processes Mediated by <i>In Situ‐</i>Deposited Phenoxazine

Abstract

Abstract Phenoxazine and quinone are typical electron mediators in natural and engineered systems. Although the electron shuttling process of quinone has been well studied, phenoxazine is poorly characterized. Here, a model phenoxazine (resazurin) was examined as an electron mediator in a bioelectrochemical system with Shewanella oneidensis MR‐1. Results showed that the current generation was substantially enhanced by the presence of phenoxazine, and was almost unaffected even after replacing the original medium with a fresh medium without phenoxazine. This is completely different to the well‐known quinones used as electron mediators. Further study suggested that, resorufin (RR), as an intermediate product, was deposited in situ onto the electrode. The RR deposition was suggested to be a dominant mechanism for stabilizing the electron shuttling efficiency by phenoxazine. This study proposed a novel electron shuttling mechanism of phenoxazine and may provide a new insight into the extracellular electron transfer.