Enhanced catalytic activity for the oxygen reduction reaction with co-doping of phosphorus and iron in carbon

The phosphorus (P) and iron (Fe) co-doped carbon (P–Fe–C) has been facilely synthesized via an in situ sol–gel polymerization method followed by a pyrolysis process using resorcinol and formaldehyde as the carbon source, tetraphenylphosphonium bromide as the P source and iron nitrate as the Fe source. Benefiting from the high doping content of P and Fe and large specific surface area, the as-prepared P–Fe–C electrocatalysts demonstrate considerable catalytic activity for the oxygen reduction reaction (ORR) as evidenced by rotating ring-disk electrode studies and show long-term stability superior to the commercial Pt/C (20 wt.%). The catalytic site of P–Fe–C for the ORR is proposed as Fe-Px (x is the coordination number of P atoms to Fe) embedded in carbon. The pyrolysis temperature is found to play an important role in the microstructure, texture and the doping content of P and Fe in carbon, which further affects the catalytic activity of P–Fe–C for ORR. •The P and Fe co-doped carbon (P–Fe–C) is facilely synthesized.•The as-prepared P–Fe–C shows high catalytic activity for the ORR.•The catalytic site of P–Fe–C for the ORR is proposed as Fe–Px.•The pyrolysis temperature plays an important role in the structure and activity of P–Fe–C.