‘Inner membrane - outer gel’ PEDOT:PSS/MXene composite material enhances the extracellular electron transfer process by promoting biofilm growth

Against the backdrop of surging global energy demand, microbial fuel cells (MFCs) have garnered significant attention for their potential in green energy conversion. To solve the problem of low efficiency of long-distance electron transfer by microorganisms at the anode interface of MFCs, we propose a novel ‘inner membrane - outer gel’ PEDOT:PSS/MXene dual-phase hydrogel electrode. The electrode is fabricated via electrochemical polymerization, which further enables it to use a flexible heterogeneous interface to promote three-dimensional (3D) biofilm generation. Experimental results indicate that the composite anode exhibits a charge transfer resistance (R_ct) as low as 4.71 Ω, with a maximum power density of 4.55 ± 0.17 W m^-2, which is 1.8 times the maximum power density of a pure hydrogel (only PEDOT:PSS hydrogel). Furthermore, 16S rRNA sequencing revealed that the relative abundance of Geobacter increased to 62.22 %, indicating a significant enrichment of electrogenic microorganisms. Molecular docking simulations further elucidated the electrostatic complementarity and hydrogen bonding interactions between PEDOT and the OmcZ protein, providing theoretical support for efficient electron transfer between conductive nanowires and electrodes within biofilms. Overall, this study provides both experimental and theoretical evidence for the feasibility of the ‘inner membrane - outer gel’ electrode in enhancing MFC performance, offering new insights into the design of high-performance conductive bioelectrodes in microbial energy conversion devices.