Metallic State FeS Anchored (Fe)/Fe<sub>3</sub>O<sub>4</sub>/N-Doped Graphitic Carbon with Porous Spongelike Structure as Durable Catalysts for Enhancing Bioelectricity Generation Xin Xu Ying Dai Jia Yu Liang Hao Yaqiang Duan Ye Sun Yanhong Zhang Yuhui Lin Jinlong Zou 10.1021/acsami.7b01531.s001 https://acs.figshare.com/articles/journal_contribution/Metallic_State_FeS_Anchored_Fe_Fe_sub_3_sub_O_sub_4_sub_N-Doped_Graphitic_Carbon_with_Porous_Spongelike_Structure_as_Durable_Catalysts_for_Enhancing_Bioelectricity_Generation/4767829 The critical issues in practical application of microbial fuel cells (MFCs) for wastewater treatment are the high cost and poor activity and durability of precious metal catalysts. To alleviate the activity loss and kinetic barriers for oxygen reduction reaction (ORR) on cathode, (Fe)/Fe<sub>3</sub>O<sub>4</sub>/FeS/N-doped graphitic carbon ((Fe)/Fe<sub>3</sub>O<sub>4</sub>/FeS/NGC) is prepared as ORR catalyst through a one-step method using waste pomelo skins as carbon source. Various characterization techniques and electrochemical analyses are conducted to illustrate the correlation between structural characteristics and catalytic activity. MFCs with Fe/Fe<sub>3</sub>O<sub>4</sub>/FeS/NGC (900 °C) cathode produces the maximum power density of 930 ± 10 mW m<sup>–2</sup> (Pt/C of 489 mW m<sup>–2</sup>) and maintains a good long-term durability, which only declines 18% after 90 day operation. Coulombic efficiency (22.2%) obtained by Fe/Fe<sub>3</sub>O<sub>4</sub>/FeS/NGC (900 °C) cathode is significantly higher than that of Pt/C (17.3%). Metallic state FeS anchored in porous NGC skeleton can boost electron transport through the interconnected channels in spongelike structure to improve catalytic activity. Charge delocalization of C atoms can be strengthened by N atoms incorporation into carbon skeleton, which correspondingly contributes to the O<sub>2</sub> chemisorptions and O–O bond weakening during ORR. Energetically existed active components (Fe and N species) are more efficient than Pt to trap and consume electrons in catalyzing ORR in wastewater containing Pt-poisoning substances (bacterial metabolites). (Fe)/Fe<sub>3</sub>O<sub>4</sub>/FeS/NGC catalysts with the advantages of durable power outputs and environmental-friendly raw material can cover the shortages of Pt/C and provide an outlook for further applications of these catalysts. 2017-03-14 00:00:00 activity loss O 2 chemisorptions N species fuel cells Durable Catalysts Metallic State FeS Anchored Enhancing Bioelectricity Generation NGC skeleton ORR catalyst metal catalysts cathode 90 day operation MFC power outputs wastewater treatment N atoms incorporation carbon source carbon skeleton catalyzing ORR Various characterization techniques electrochemical analyses oxygen reduction reaction waste pomelo skins electron transport spongelike structure power density charge delocalization Porous Spongelike Structure Pt-poisoning substances C atoms