Bimetallic zeolitic imidazole framework derived Co@NC materials as oxygen reduction reaction catalysts application for microbial fuel cells

Abstract

Microbial fuel cells (MFCs), a promising future energy conversion technology, play a significant role in the area of sustainable and renewable energy. In air-cathode MFCs, the catalytic activity for oxygen reduction reaction (ORR) of cathode electrocatalyst is the key factor to the performance of MFCs. Development of efficient and economical ORR electrocatalysts is an important step for the wide application of MFCs. Herein, Co wrapped carbon nanotubes (CNTs) N-doped nanoporous carbon materials (Co@NC-Co x Zn y ) are constructed via a facile zinc-assisted growth pyrolytic approach of bimetallic zeolitic imidazole frameworks (BMZIFs)-derived strategy. They are directly prepared via carbonization of the precursor Co x Zn y -BMZIFs. During the pyrolysis process, the evaporation of zinc plays critical role in the in-situ growth of CNTs. For instance, the optimal catalyst, Co@NC-Co 1 Zn 3 , exhibits excellent ORR performance activity and stability with on-set potential ( E on-set ) of 0.830 V ( vs. RHE) and diffusion-limited current density ( j L ) of 6.706 mA cm −2 , which is superior to the benchmark catalyst of commercial 20 wt% Pt/C. Additionally, Co@NC-Co 1 Zn 3 displays four-electron pathway, long-term stability and better resistance to methanol tolerance. The MFC with Co@NC-Co 1 Zn 3 cathode shows a maximum power density of 1039 mW m −2 , and outperforms the MFC with commercial 20 wt% Pt/C catalyst (678 mW m −2 ). This work paved the way for exploring cost-effective, superior performance non-precious metal-based catalysts for air-cathode MFCs. • A facile, cost-effective, Co@NC-Co 1 Zn 3 exhibits superior ORR performance and long-term stability. • A zinc-assisted evaporated produces Co@CNTs structure, which is the essential for the superior ORR activity. • The maximum power density of Co@NC-Co 1 Zn 3 -MFC is higher than that of Pt/C-MFC.