Fe–N–C Composite Catalyst Derived from Solid Digestate for the Oxygen Reduction Reaction in Microbial Fuel Cells

Abstract

Transforming biomass waste into cost-effective non-precious-metal catalysts for the oxygen reduction reaction (ORR) provides a great opportunity for the development of microbial fuel cells (MFCs). Herein, we report a strategy to produce Fe–N–C composites from the biomass waste and evaluate their performance as ORR electrocatalysts, involving the co-doping of Fe and N and the construction of hierarchical structure with high surface areas. The obtained catalyst, with abundant defect sites and uniform Fe and N dispersions, showed excellent activity and selectivity toward the ORR due to the synergetic effect between the doped N and Fe. In particular, with the Fe–N–C as electrocatalysts, MFCs could produce a maximum power density of up to 1308 mW m–2, much higher than that of the N–C catalyst (638 mW m–2). This newly developed method, with the advantage of easily scaling up for mass production of Fe–N–C composites, not only provides an effective approach to fabricate value-added functional carbon materials but also offers an efficient way to mitigate the biomass waste-related environmental pollution.