Three-dimensional macroporous structure and surface carbon-coating modification of stainless-steel anode boost bioelectrocatalytic performance

[Display omitted] •A novel stainless-steel based electrode was proposed for the scaling-up of BESs.•Surface carbon-coating modification greatly improved electrode’s biocompatibility.•Macroporous structure enabled well mass transfer through electrode.•Projected current density increased linearly with increase of electrode thickness. Bioelectrochemical systems (BESs) is a promising and sustainable technology for wastewater treatment, and the practical application of BESs generally requires scalable three-dimensional (3D) electrodes. In this study, we present a stainless-steel crochet mesh electrode (P-SS) with 3D macroporous structure, and modified by carbon coating through pyrolyzing residual lubricating oil in the mesh production process. The effect of 3D macroporous structure and surface carbon-coating modification on the improvement of electrode bioelectrocatalytic performance was investigated during the study. When the electrode was used as the anode in BESs reactors, a superior bioeletrocatalytic current was generated, reaching a maximum projected current density of 9.95 mA·cm−2 and achieving a highest geometric current density of 1.89 mA·cm−2 ever recorded. We found the 3D macroporous structure and surface carbon-coating modification enabled the electrode well mass transfer, excellent biocompatibility and fluent electron transport, finally boosted the superior bioeletrocatalytic performance. We also verified the electrode has a remarkable stackability as suggested by the bioelectrocatalytic current increasing linearly with the increase of electrode thickness. In addition, the acceptable capital cost (＜6500 $·m−3), adequate mechanical strength and feasible industrial process of this novel electrode all indicate its great prospects for the scaling-up of BESs.