High-performance FeOx@CoOx/NC electrocatalysts for the oxygen reduction reaction in alkaline media

Abstract

Herein, cobalt oxide encapsulated nitrogen-doped tubular carbon (CoOx/NC) is derived via one-step carbonization of ZIF-12. Iron oxide nanoparticles are then generated over the CoOx/NC support by decomposition of the iron phenanthroline complex to obtain FeOx@CoOx/NCs. The synthesized electrocatalysts are tested for the oxygen reduction reaction (ORR). The optimized electrocatalyst FeOx@CoOx/NC2 exhibits superior activity to 20 wt% Pt/C in 0.1 M KOH with the E1/2 = 0.89 VRHE, Eonset=1.03 VRHE and j = 6.32 mA cm−2 values. The enhanced activity is attributed to the cumulative effect of FeOx, CoOx and presence of four types of nitrogen atoms. For comparison, FeOx@MWCNTs demonstrates lower activity than the synthesized catalysts (E1/2 = 0.76 VRHE and Eonset = 0.94 VRHE) which proves the synergistic role of CoOx towards the ORR. The oxygen reduction reaction ability of the synthesized catalyst (FeOx@CoOx/NC2) is also investigated in the presence of 0.5 M methanol. The catalyst exhibits enhanced tolerance to methanol addition. The accelerated durability test (ADT) performed in 0.1 M KOH over 10 000 cycles shows a decay of only 17 mV.