High-performance FeO _x @CoO _x /NC electrocatalysts for the oxygen reduction reaction in alkaline media

Abstract

FeO _x decorated, and cobalt oxide encapsulated nitrogen-doped tubular carbon (FeO _x @CoO _x /NC2) as efficient electrocatalyst for ORR.

Abstract

Herein, cobalt oxide encapsulated nitrogen-doped tubular carbon (CoO _x /NC) is derived via one-step carbonization of ZIF-12. Iron oxide nanoparticles are then generated over the CoO _x /NC support by decomposition of the iron phenanthroline complex to obtain FeO _x @CoO _x /NCs. The synthesized electrocatalysts are tested for the oxygen reduction reaction (ORR). The optimized electrocatalyst FeO _x @CoO _x /NC2 exhibits superior activity to 20 wt% Pt/C in 0.1 M KOH with the E _1/2 = 0.89 V _RHE, E _onset=1.03 V _RHE and j = 6.32 mA cm ⁻² values. The enhanced activity is attributed to the cumulative effect of FeO _x , CoO _x and presence of four types of nitrogen atoms. For comparison, FeO _x @MWCNTs demonstrates lower activity than the synthesized catalysts ( E _1/2 = 0.76 V _RHE and E _onset = 0.94 V _RHE) which proves the synergistic role of CoO _x towards the ORR. The oxygen reduction reaction ability of the synthesized catalyst (FeO _x @CoO _x /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.