Synthesis of active iron-based electrocatalyst for the oxygen reduction reaction and its unique electrochemical response in alkaline medium

摘要

Efficient iron-based electrocatalyst for the oxygen reduction reaction (ORR) in alkaline medium was synthesized by facilely modifying single-walled carbon nanotubes (SWCNTs) with iron tetrasulfophthalocyanine (FeTSPc). The resulting FeTSPc/SWCNTs composite was characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectrum, Fourier transform infrared spectroscopy (FTIR) and Raman spectrum, which confirmed that FeTSPc could be strongly supported onto SWCNTs through π-π interaction. Cyclic voltammetry and rotating disk electrode results revealed that the ORR catalyzed by FeTSPc/SWCNTs presented a direct four-electron pathway with a very positive onset potential (+0.05 V vs Ag/AgCl, 3 M KCl), cathodic peak potential (-0.10 V vs Ag/AgCl, 3 M KCl) and a large kinetic rate constant (2.31 × 10~(-2) cm s~(-1)). Besides, FeTSPc/SWCNTs displayed an even better specificity, long-term stability, tolerance to methanol crossover effect and resistance toward CO poisoning effect than the commercial Pt/C catalyst (40%). Further, the catalytic mechanism of ORR and the unique electrochemical behavior of the active sites in FeTSPc/SWCNTs were also been elucidated.