Spray coating of carbon nanoparticles as an effective and scalable method to enhance the performance of stainless steel anode in microbial electrochemical systems

Modifying stainless steel (SS) surfaces with biocompatible materials is a practical approach to making SS an efficient electrode material for microbial electrochemical systems (MESs). However, a simple, cost-effective method to modify large-size SS is still missing. Here, we proposed to use spray coating to modify SS mesh (SSM) with acetylene black (AB) nanoparticles to make SSM an efficient anode material for MESs. The SEM images and Raman spectrum confirmed that AB nanoparticles could be uniformly coated onto the surface of SSM. The AB nanoparticles dramatically increased the specific surface area and biocompatibility of SSM. Consequently, when tested as the anode in MESs, the AB-coated SSM exhibited excellent biofilm formation ability, while the bare SSM saw inferior biofilm formation potential. Moreover, the current density achieved on the AB-coated SSM (1.95 ± 0.1 mA/cm²) was orders of magnitudes higher than that achieved on the bare SSM (0.01 ± 0.01 mA/cm²). Compared to other surface modification methods for SS, spray coating is simple, cost-effective, and most importantly readily for large-size SS electrodes. Therefore, spray coating of carbon nanoparticles holds excellent potential for scaling up SS electrodes for MESs.