Engineering dual metal single-atom sites with the nitrogen-coordinated nonprecious catalyst for oxygen reduction reaction (ORR) in acidic electrolyte

An electrocatalyst composed of dual metal single-atom sites attached to nitrogen-doped porous carbon was made in the current study developing a host-guest design. Co single atoms/nitrogen-doped carbon (Co SAs/NC), Fe SAs/NC, and Co-Fe SAs/NC electrocatalysts were successfully synthesized to evaluate their oxygen reduction reaction (ORR reaction activity) in an acidic medium. Co-Fe SAs/NC shown remarkable oxygen reduction reaction (ORR) performances compared to other samples due to the porous structures from their N-doped porous carbon and dual-site of Fe-Zn or Co-Fe. The respective onset potential and the limiting current density values for Co-Fe SAs/NC are 0.86 VRHE and 6.34 mA cm(-2) in 0.1 M HClO4. In contrast with commercial 10 wt% Pt/C, the Co-Fe SAs/NC possess a small electrochemical impedance. It is worth noting that 90.31% and 73.24 % of the initial current density of Co-Fe SAs/NC are remained after 15,000 and 40,000 s in durability measurements. Besides, after 40k durability cycles, the Co-Fe SAs/NC was more stable than commercial Pt/C. Therefore, the Co-Fe SAs/NC can be considered an encouraging ORR catalyst to be utilized in fuel cells to address the problems associated with slow ORR kinetics and high durability.

Automated summary

In this study, an electrocatalyst composed of dual metal single-atom sites attached to nitrogen-doped porous carbon was developed using a host-guest design. Co-Fe SAs/NC showed remarkable oxygen reduction reaction (ORR) performances compared to other samples, with higher onset potential and limiting current density values, and greater stability in durability measurements. This suggests that Co-Fe SAs/NC could be a promising ORR catalyst for use in fuel cells to improve ORR kinetics and durability.