Molten salt synthesis of ZIF derived CoFe alloy embedded in 2D ultrathin N-doped porous carbon nanosheets for efficient alkaline media oxygen electrocatalysis

Abstract

Developing advanced electrocatalysts for cooperative oxygen electrocatalysis is significant to metal-air batteries. Herein, we report a novel and simple molten salt approach for constructing CoFe alloy embedded in 2D ultrathin N-doped porous carbon nanosheets (CoFe/NPC). Furthermore, the pyrolysis temperature and Co/Fe molar ratio were optimized for high activity. As expected, the optimal Co0.5Fe0.5/NPC-900 manifests outstanding catalytic activity and durability for bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). It only needs a positive half-wave potential of 0.89 V to drive ORR and a low overpotential of 318 mV to afford 10 mA·cm−2 for OER, outperforming that of commercial Pt/C and RuO2. More impressively, excellent durability with continuous operation is also achieved. The numerous exposed catalytic sites, the accelerated mass and charge transfer, and the interplay between CoFe alloy and the 2D ultrathin N-doped carbon species account for the enhanced catalytic performance of CoFe/NPC. Similarly, the architecture of porous substrate anchoring CoFe alloy enables long-term durability due to strong metal-support interaction.