Effect of Active Site Poisoning on Iron−Nitrogen−Carbon Platinum‐Group‐Metal‐Free Oxygen Reduction Reaction Catalysts Operating in Neutral Media: A Rotating Disk Electrode Study

• Published in: ChemElectroChem Vol. 7; no. 14; pp. 3044 - 3055
• Main Authors: Ficca, Valerio C. A., Santoro, Carlo, D'Epifanio, Alessandra, Licoccia, Silvia, Serov, Alexey, Atanassov, Plamen, Mecheri, Barbara
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 16.07.2020
• Subjects: Biochemical fuel cells; Catalysts; Chlorides; Contaminants; Electrodes; Microorganisms; Oxygen reduction reactions; Parameter identification; performance recovery; platinum group metal-free catalysts; Platinum metals; Poisoning; poisoning effect; rotating disk electrode; Rotating disks; Rotation; Tafel analysis; Wastewater
• ISSN: 2196-0216; 2196-0216
• DOI: 10.1002/celc.202000754

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−), perchlorate (ClO4−), and nitrate (NO3−) in the concentration range of 0.05–50 mM. Onset potential (Eonset), half‐wave potential (E1/2), limiting disk current density (Jlim) 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. What's your poison? Poisoning tolerance to anions of platinum‐group‐metal‐free electrocatalysts is investigated through rotating disk electrode studies. Chloride, perchlorate and nitrate contaminants have limited or no impact on Fe−N−C catalysts. Nitrite negatively affects the electrocatalytic activity of Fe−based catalysts.