Enrichment of electrogenic microbes on surface-modified stainless steel 304L for rapid start-up of microbial electrochemical sensors

Abstract

Stainless steel (SS) 304L, a cost-effective and mechanically robust material, is widely used in microbial electrochemical systems as an anode due to its versatility. However, poor biocompatibility and low corrosion resistance limit its potential. This study explores rapid SS surface modification techniques to enhance the sensitivity of microbial electrochemical sensors. Four coatings, namely electroreduction, carbon-coated, flame oxidised, and graphene-coated, were applied to SS electrodes. Surface morphology and characteristics were examined through FESEM-EDX and Raman profiling. The biosensor start-up and microbial enrichment demonstrated an exponential increase in current density, with carbon-based electrodes outperforming iron-based ones. The modified electrodes exhibited enhanced microbial-electrode interactions, evident in altered electrode potential. Starvation and recovery tests revealed distinct patterns, with carbon-coated electrodes showcasing rapid recovery. The air-in-chamber test indicated immediate loss and subsequent recovery of microbial activities upon water circulation. Surface modification significantly influenced the microbial response, with carbon-based coatings demonstrating superior performance. This study provides valuable insights into SS surface modification for improving microbial electrochemical sensor sensitivity, holding promise for diverse applications in environmental monitoring and biosensing.