Autogenic pressure derived Fe/FeOx encapsulated Fe-Nx doped carbon as ultra-durable and superior oxygen reduction reaction electrocatalyst

A significant challenge impeding the commercialization of fuel cell technology is the utilization of a high cost and poor stability of the noble platinum nanoparticles supported on carbon (Pt/C) as an oxygen reduction reaction (ORR) electrocatalyst at the cathode electrode. Herewith, we report the extremely durable and superior ORR electrocatalyst derived from Fe/FeOx encapsulated iron coordinated nitrogen doped carbon (FeNC) nanostructure by simply calcining the solid mixture containing oxidized carbon nanoparticle, melamine and iron (II) acetate at 700 (FeNC700), 800 (FeNC800) and 900 °C (FeNC900) under autogenic pressure condition. The maximum ORR performance with Eonset and E1/2 value of 1.04 and 0.89 V vs. RHE is achieved with the FeNC sample heated at 700 °C. The benchmark Pt/C electrocatalyst delivers Eonset value of 1.04 V vs. RHE and E1/2 value of 0.86 V vs. RHE. On the other hand, the FeNC catalyst promotes ORR process via a direct 4 electron transfer route accompanied by an extremely low number of intermediate substances. To understand the outstanding ORR performance of the synthesized catalysts, microstructure, phase, surface area and Fe-Nx active site are investigated. It is found that the FeNC sample with larger content of Fe-Nx active site coupled with the presence of Fe/FeOx encapsulated graphitic Fe-Nx doped carbon structure results in the remarkably high ORR performance under alkaline media. Furthermore, the FeNC700 sample exhibits not only excellent resistance to methanol poisoning, but also negligible ORR degradation against the accelerated ORR durability test for 5,000 cycles.