Enhancing microbial extracellular electron transfer efficiency through increased configuration entropy of bioanodes

Abstract

Microbial fuel cells (MFCs) have garnered significant attention in the field of bioelectrochemistry as a clean energy source, with a focus on increasing their power density. This study reports the successful application of a spinel-type high-entropy oxide (Mg0.2Co0.2Ni0.2Cu0.2Zn0.2)Fe2O4 as an anode material for microbial fuel cells. The samples were prepared through ball milling and sintering at 900 °C. Electrochemical tests demonstrated that the high-entropy oxide significantly enhanced the electrochemical performance and biocompatibility of the anode. The MFCs loaded with (Mg0.2Co0.2Ni0.2Cu0.2Zn0.2)Fe2O4 exhibited a power density of up to 3.43 W/m2, which is significantly higher than that of a simple mixture of six metals (2.61 W/m2) and pure Fe2O3 (2.64 W/m2). This outstanding performance results from the disorder induced by the high-entropy composition. This disorder facilitates improved coordination among the primary constituent oxides, maximizing their advantages. Simultaneously, it minimizes the reduction in active sites caused by uneven distribution. High-throughput sequencing results revealed an enrichment of Geobacter in the anodic biofilm, reaching a content as high as 52.51% after domestication. This study elucidates the contribution of entropy to biocatalysis from an entropy perspective and provides a new strategy for developing high-performance materials for microbial fuel cells.