Prussian blue-derived FeNx/Fe-based N-doped carbon nanotube catalysts with high ORR electrochemical performance

Abstract

The oxygen reduction reaction (ORR) kinetics are slow, limiting the overall reaction rate. It is still challenging to construct transition metal-based electrocatalysts with high activity and stability. In this study, FeN_x/Fe-based skewer-like N-doped carbon nanotubes (FeN_x/Fe-NCNTs) are successfully prepared by a simple one-step pyrolysis strategy. The Fe-based nanoparticles are evenly dispersed at the tip of the carbon nanotubes and the junction of the bamboo segments, indicating that the FeN_x/Fe-NCNTs catalyst has abundant ORR active sites. When applied to the ORR, FeN_x/Fe-NCNTs exhibit initial and half-wave potentials of 0.96 and 0.86 V (vs. RHE) in 0.1 M KOH, comparable to those of commercial 20% Pt/C catalysts. Moreover, the FeN_x/Fe-NCNTs showed a low Tafel slope value of 81.2 mV dec⁻¹ and the electron transfer number (n) is between 3.81 and 3.93, indicating a fast four-electron transfer path. The results show that FeN_x/Fe-NCNTs have better electron transfer efficiency and stability, making them an excellent ORR catalyst.