Recent advances and challenges in microbial fuel cell anode engineering for sustainable energy recovery

Abstract

Microbial fuel cells (MFCs) offer a promising wastewater treatment method to produce electricity. However, the performance and long-term stability of anode materials still restricts the large-scale application of microbial fuel cells (MFCs). Recent advances in anode engineering are reviewed, particularly in terms of material design and application. The existing modification strategies can be classified generally into three categories: surface modification, construction of three-dimensional nanostructures, and integration of multifunctional materials. Surface treatments—such as acid oxidation, conductive polymer coating, or heteroatom doping—improve electrode wettability, microbial attachment, and electron transfer at the microbe–electrode interface. These coatings are however, not always stable and long lasting and the effective surface area of planar electrodes is limited. Three dimensional carbon structures like carbon felt, graphene foam or carbon nanotube networks provide larger surface areas for microbial colonization and facilitate direct electron transfer, but challenges of pore accessibility and the mechanical strength as well as scalable production remain. Multifunctional composites with conductive frameworks, catalytic components and biocompatible surfaces frequently show good performance in a lab environment, but their complex preparation and poor stability at practical operating conditions are still obstacles for the extension of this application. In this review, areal power density and coulombic efficiency are also important engineering metrics to assess electricity generation and substrate conversion. In practice, when developing MFCs, there needs to be a compromise made between electrical conductivity, biocompatibility, long-term durability and manufacturing cost. The future studies should be focused on mechanism oriented material design, standardization of experimental testing, long term operation under realistic conditions, and simple and low cost production methods.