Facile ionothermal synthesis of mesoporous Fe–Nx–C composites as efficient catalysts for oxygen reduction in acid media

Abstract

The development of high performance non-precious catalysts is still significant for the promising wide application of proton-exchange membrane (PEM) fuel cells. In this work, a facile ionothermal polymerization approach was developed to synthesize highly active covalent triazine framework (CTF) derived Fe–N_x–C catalysts for mediating the cathodic reaction of fuel cells. The impacts of the heating temperature, dosage of ZnCl₂, and dinitrile aromatic monomers on the oxygen reduction reaction (ORR) activity of Fe–N_x–C catalysts were systematically discussed. High performance CTF-derived Fe–N_x–C catalysts were successfully obtained, among which the FB7 exhibits an extraordinary ORR performance in 0.1 M HClO₄ aqueous solution. The linear sweep voltammetry (LSV) results show that there are only 14 mV and 25 mV slightly negative shifts of the onset potential (E_onset) and half-wave potential (E_1/2) of FB7 comparing with those of commercial Pt/C (20 μg Pt per cm²). Besides, FB7 also shows better electrochemical stability and methanol-tolerance than Pt/C. This outstanding ORR performance of FB7 is attributed to its excellent percolation properties and high density of active sites.