Interface Decoration of N-Doped Carbon Nanotube with Fe for Enhancing Oxygen Catalytic Activity

Abstract

Oxygen electrocatalytic reactions, including oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are extremely important in energy storage and conversion technology. The ORR is happened in cathode electrode in fuel cells or metal air batteries when discharging, the OER is occurred in anode electrode in water splitting or rechargeable metal air batteries when charging. Currently, the high-performance catalyst developed for ORR still relies on platinum (Pt) and its alloys. On the other hand, ruthenium (Ru) oxides were demonstrated to be high performance electrocatalysts for OER. However, their scarcity, limited stability, and aggregation limited the development of electrochemistry energy storage and conversion. Herein, we synthesize a series of transition metal nanoparticles embedded in nitrogen doped carbon nanotubes (M-CNT) and further decorating the interface of N-CNT with Fe element for enhancing oxygen catalytic activities. The results show that the type of transition metal determine the morphologies of N-CNT and the catalytic performance in ORR and OER. After further modification by introducing Fe element, the Fe-CNT based catalyst displays a superior ORR activity, even surpasses that of Pt/C, the Ni-CNT based catalyst with Fe decoration also showes a significant enhancement in OER. This work provides a feasible strategy to develop highly efficient oxygen catalysts with low-cost, earth-abundant transition metal elements via further decoration.