Catalyzing oxygen reduction by morphologically engineered ZIF-derived carbon composite catalysts in dual-chamber microbial fuel cells

• Published in: Journal of environmental chemical engineering Vol. 12; no. 2; p. 112242
• Main Authors: Kumar, Rohit, Mooste, Marek, Ahmed, Zubair, Zekker, Ivar, Käärik, Maike, Marandi, Margus, Leis, Jaan, Kikas, Arvo, Otsus, Markus, Treshchalov, Alexey, Aruväli, Jaan, Jaagura, Madis, Kisand, Vambola, Tamm, Aile, Tammeveski, Kaido
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2024
• Subjects: Electrocatalysis; M-N-C catalyst; Microbial fuel cell; Non-precious metal catalyst; Oxygen reduction reaction; Zeolitic imidazolate framework; Electrocatalysis; M-N-C catalyst; Zeolitic imidazolate framework; Microbial fuel cell; Non-precious metal catalyst; Oxygen reduction reaction
• ISSN: 2213-3437; 2213-3437
• DOI: 10.1016/j.jece.2024.112242

From the past decades, microbial fuel cells (MFCs) have evolved as a green alternative to produce electrical energy from organic matter degradation. Cathode modification significantly enhances the overall MFC performance. In this work, we report on ZIF-8 and carbon nanotubes (CNTs) derived catalyst materials as cathode for MFC. The catalysts were prepared via high-temperature pyrolysis at 900 °C and were physically characterized by various analytical techniques. All the catalyst materials carry tubular arrangements of CNTs covering the ZIF-8 crystals and exhibit highly micro-mesoporous texture. The electrocatalytic activity for oxygen reduction reaction (ORR) was studied in 0.1 M phosphate buffer at a catalyst loading of 0.2 mg cm−2. The FeCo-N-C@900 catalyst showed the highest ORR activity with half-wave potential of 0.71 V vs RHE and limiting current density of −5.62 mA cm−2 at 1900 rpm. When tested in MFC, FeCo-N-C@900 coated cathode delivered the maximum power density of 1557 mW m−2 (comparable to Pt/C catalyst reaching Pmax of 1681 mW m−2) with chemical oxygen demand (COD) removal efficiency of 87.3%. The Next generation DNA sequencing analysis revealed the accumulation of various exoelectrogenic bacterial strains i.e., Bacillus, Desulfovibrio, Comamonadaceae sp. etc. commonly found in anaerobic biomass and showing the successful enrichment of the biofilm responsible for oxidizing organic matter at the anode. The present study illustrates the potential of transitional metal-doped ZIF-8 and CNTs composite electrocatalysts for enhancing the power output of MFC with generating promising power and current densities. [Display omitted]