Temperature-field multiscale regulated 3D PVA-PPy conductive hydrogel for enhanced bio-electrocatalytic performance

Microbial fuel cells (MFCs) have been proven to be a green technology for solving energy crises, but their low power density limits their large-scale practical applications. In this paper, a three-dimensional porous composite hydrogel polyvinyl alcohol/polypyrrole (PVA/PPy) with good biocompatibility was prepared by temperature-field regulation via alternating cycles between low temperature (- 20 °C) and room temperature (25 °C) and used as the anode in MFC. The three-dimensional network structure of PPy nanospheres compressed by ice crystal stress exhibited excellent charge conduction capability and ion transport performance, which significantly improved the interfacial charge transfer efficiency of PVA/PPy-5 bioanode. Besides, the addition of PVA endowed the hydrogel with mechanical properties to resist the external forces. As the results, the maximum power density of PVA/PPy-5 MFC was 1521.04 mW/m², which was 1.76, 2.16 and 8.32 times higher than that of PVA/PPy-0, PPy-5 and carbon felt MFCs, respectively. Such enhancement could be attributed to the combined effects of three factors, including the FT process, biocompatibility of PVA, and bioelectrocatalytic activity of polypyrrole. The high-throughput sequencing technology revealed that the PVA/PPy-5 hydrogel anode, which facilitated the selective enrichment of electrogenic microbes, played a crucial role on the regulation of functional biofilm. This work provides a new approach for developing high-performance electrodes for MFC.