In this work, benzimidazole
(BZIM) and aminobenzimidazole (ABZIM)
were used as organic-rich in nitrogen precursors during the synthesis
of iron–nitrogen–carbon (Fe–N–C) based
catalysts by sacrificial support method (SSM) technique. The catalysts
obtained, denoted Fe-ABZIM and Fe-BZIM, were characterized morphologically
and chemically through SEM, TEM, and XPS. Moreover, these catalysts
were initially tested in rotating ring disk electrode (RRDE) configuration,
resulting in similar high electrocatalytic activity toward oxygen
reduction reaction (ORR) having low hydrogen peroxide generated (<3%).
The ORR performance was significantly higher compared to activated
carbon (AC) that was the control. The catalysts were then integrated
into air-breathing (AB) and gas diffusion layer (GDL) cathode electrode
and tested in operating microbial fuel cells (MFCs). The presence
of Fe–N–C catalysts boosted the power output compared
to AC cathode MFC. The AB-type cathode outperformed the GDL type cathode
probably because of reduced catalyst layer flooding. The highest performance
obtained in this work was 162 ± 3 μWcm–2. Fe-ABZIM and Fe-BZIM had similar performance when incorporated
to the same type of cathode configuration. Long-term operations show
a decrease up to 50% of the performance in two months operations.
Despite the power output decrease, the Fe-BZIM/Fe-ABZIM catalysts
gave a significant advantage in fuel cell performance compared to
the bare AC.
In this work, we initially report a detailed advancement in the utilization of metal-N 4 chelate macrocycles in the oxygen reduction reaction (ORR). Then, iron(II) phthalocyanines supported on two different carbon-based supports specifically carbon nanotube and black pearl (carbon spheres) were synthesized and their activities toward ORR in alkaline media were studied. With the help of physical and surface characterization like Raman, BET, XRD, XPS, and electron microscopy analysis, the similarity in surface chemistry and surface area of the materials and the differences in the structure and morphology of the supports were established. This work also brings forth the effect of support properties on the electrocatalytic activity of the materials by a detailed electrochemical analysis using rotating disk electrode in oxygen saturated 0.1 M KOH. Comparison with existing literature on Fe-phthalocyanine supported on diverse carbon support is presented.
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