Microbial extracellular electron transfer (EET) with high performance and good controllability is always desired in various bioelectric applications. Depending on the redox state, C-type cytochromes located across the outer membranes (OMCs) mediate EET with different behaviors. Here, by incorporating Sn-doped In2O3 nanowire array with flat F-doped In2O3 (FTO), a composite electrode is developed that can highly boost EET by over 60 times at a certain potential of 0.2 V, where normally only limited EET current is observed on a conductive electrode. It is proposed that the underlay FTO with bias 0.2 V promotes EET via OMCs by physical contacting with microbes, while the semiconductor nanowires provide a suitable energy level to facilitate the EET via OMC-flavins cofactor, breaking the stereotype of the certain redox state of OMCs at a given potential. As a synergistic effect, EET via both OMCs and flavins is highly boosted simultaneously to achieve the dual-pathway EET, which could be further amplified by the nanostructured topology of the as-prepared electrode. Moreover, the EET current shows a positive correlation with the nanowire length, showing good controllability. This work provides an applicable method for constructing various highly efficient bioelectric devices.
- electron transfer
- Sn-doped InO nanowires