Enhancing oxygen reduction reaction in acidic medium: A novel electrocatalyst of Pt–Co embedded in nitrogen-rich carbon nanosheets derived from polypyrrole-g-C3N4

Abstract

In this study, PtCo alloy nanoparticles (NPs) were successfully synthesized and deposited on nitrogen-rich carbon nanosheets derived from Polypyrrole-g-C₃N₄ using a chemical reduction method. This electrocatalyst not only offers enhanced catalytic efficiency but also significantly improves the stability for the oxygen reduction reaction (ORR) in in acidic medium. In terms of electrocatalytic performance, the PtCo/CN@PPY-g-C₃N₄ catalyst demonstrated a mass activity of 0.378 mA µg_Pt⁻¹ at 0.85 V, 0.131 mA µg_Pt⁻¹ at 0.9 V and a specific activity of 2.900 mA cm_Pt⁻² at 0.85 V, 1.004 mA cm_Pt⁻² at 0.9 V which are respectively 2.3, 2.8 and 10, 12 times higher than those of a commercial 20% Pt/C catalyst (0.166 mA µg_Pt⁻¹ at 0.85 V, 0.046 mA µg_Pt⁻¹ at 0.9 V and 0.285 mA cm_Pt⁻² at 0.85 V, 0.079 mA cm_Pt⁻² at 0.9 V). This indicates superior catalytic activity. Furthermore, after 5000 cycles, the PtCo/CN@PPY-g-C₃N₄ retained approximately 77% at 0.85 V and 83% at 0.9 V of its initial mass activity, with only a 14 mV decrease in the half-wave potential, whereas commercial 20% Pt/C catalyst retained only 40% at0.85 V and 30% at 0.9 V of its initial mass activity. These enhancements can be attributed to the synergistic effects and strong interactions between the Pt–Co alloy nanoparticles and the carbon nitride support. The findings of this study underscore the potential of PtCo/CN@PPY-g-C₃N₄ as a viable and efficient alternative to traditional catalysts in electrochemical applications.