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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.

Platinum-group-metal-free (PGM-free) catalysts are the most promising materials to substitute expensive platinum catalysts for efficient oxygen reduction reaction (ORR), particularly for microbial fuel cells. For these devices, contamination due to wastewater is one of the major issues, owing to the presence of various poisoning anions. The known nitrite contamination effect over PGM-free catalysts was studied by using the rotating disk electrode (RDE) technique in neutral media to understand its patterns. The results were then compared to other contaminants commonly found in wastewater such as chloride (Cl À ), perchlorate (ClO 4 À ), and nitrate (NO 3 À ) in the concentration range of 0.05-50 mM. Onset potential (E onset ), half-wave potential (E 1/2 ), limiting disk current density (J lim ) and Tafel slope variations were the parameters exploited to identify specific or nonspecific adsorbed contaminants. Chloride and nitrate had no negative effect on ORR performance, whereas perchlorate slightly reduced the catalyst function with no permanent issues. Durability tests (1000 cycles) were also performed to ensure the stability of the catalyst for the relatively long time.

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