Sn–Fe Dual-Metallic Nanoparticles on S,N-Codoped g-C ₃ N ₄ -Derived Tubular Carbon as an Efficient Bifunctional Catalyst for Oxygen Reduction Reaction and Oxygen Evolution Reaction

Developing cost-effective, high-performance bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial for advanced clean energy technologies. This work details Sn–Fe bimetallic nanoparticles anchored on S,N-codoped graphitic carbon nitride (C3N4)-derived tubular carbon (SnFe/SNC_T), which are synthesized via a facile pyrolysis method at 850 °C (SnFe/SNC_850). The optimized SnFe/SNC_850 catalyst, which is characterized by a distinct bamboo-like tubular morphology, demonstrates superior ORR activity with a half-wave potential (E1/2) of 0.86 V vs RHE in 0.1 M KOH, surpassing commercial Pt/C (0.82 V). Furthermore, it exhibits excellent OER performance, requiring only 340 mV overpotential to achieve 10 mA cm–2, and displays remarkable overall bifunctionality. When SnFe/SNC_850 is integrated into an anion exchange membrane fuel cell (AEMFC), it delivers a peak power density of 277 mW cm–2, significantly outperforming Pt/C-based cells (168 mW cm–2). The catalyst also demonstrates exceptional durability, with only 20 mV of E1/2 decay after 30,000 cycles, compared to 50 mV for Pt/C. This enhanced performance is attributed to the synergistic interplay between Fe–Nx/Fe–Sx active sites and intermetallic Fe3SnC/FeS domains. These findings establish SnFe/SNC_850 as a highly promising nonprecious-metal bifunctional electrocatalyst for practical energy-conversion applications, paving the way for sustainable clean-energy solutions.