Metal-doped (Fe-Mn) heteroatom-rich porous biochar-based poison-resilient cathode catalyst for enhanced performance of microbial fuel cell

Abstract

Developing cost-effective and superior catalysts for the oxygen reduction reaction (ORR) is paramount for successfully commercializing microbial fuel cells (MFCs) as a sustainable, reliable and economical alternative for energy recovery and wastewater treatment. In this investigation, metal-doped heteroatom (Nitrogen-Sulphur-Carbon) rich porous biochar (Metal-NSC) was synthesized by incorporating different metal and bi-metal dopants into activated human hair (HH) biochar. Out of which, the synthesized Fe/Mn-NSC catalyst has a porous structure that enables it to have a high specific surface area (615.04 m²/g), a large pore volume (0.4342 cm³/g), and numerous defects (I_D/I_G = 1.02). The Fe/Mn-NSC demonstrates exceptional performance in the ORR, and the performance of MFC using Fe/Mn-NSC as a cathode catalyst stands out with a higher power density (14.6 ± 0.6 W/m³), which was 1.74 and 1.14 times compared to only HH biochar (NSC) (8.4 ± 0.1 W/m³) and commercial Pt/C (12.8 ± 0.3 W/m³), respectively. Thus, the Fe/Mn-NSC catalyst exhibits promising potential to harvest more power per unit cost (64.69 mW/$) and superior alternative to commercial Pt/C catalyst (3.11 mW/$) for widespread deployment for practical applications in MFCs.