Microstructuring Conductive Electrospun Mats for Enhanced Electro-active Biofilm Growth and High-Performance Bioelectrocatalysis

Electrospun materials have attracted considerable attention in microbial fuel cells (MFC) owing to their porous structures, which facilitate the growth of electro-active biofilms (EABs). However, the impact of fiber diameter-controlled porous architectures on EAB growth and MFC performance has not been extensively studied. Herein, a highly conductive polypyrrole-modified electrospun polyacrylonitrile (PAN) mat was prepared as an electrode material for Shewanella putrefaciens CN32-based MFCs. The dominant pore size of the corresponding mat increases from 1 to around 20 mu m as the fiber diameter increases from 720 to 3770 nm. This variation affects the adhesion and growth behaviors of electrochemically active bacteria on the mat-based electrodes. The electrodes with poresranging from 2 to 10 mu m allow bacterial penetration into the interior, leading to significant biofilm loading and effective bioelectrocatalysis. However, the tight lamination of the electrospun fibers restricts bacterial growth in the deep interior space. We developed a friction-induced triboelectric expanding approach to rendering the mats with layered structures to overcome this limitation. The inter- layer spaces of the expanded conductive mat can facilitate bacterial loading from both sides of each layer and serve as channels to accelerate the catalysis of organic substances. Therefore, the expanded conductive mat with appropriate pore sizes delivers superior bioelectrocatalytic performance in MFCs and dye degradation. Based on the findings, a mechanism for the porous structure-controlled EAB formation and bioelectrocatalytic performance was proposed. This work may provide helpful guidance and insights for designing microfiber-based electrodes for microbial fuel cells.