Abstract
A novel and facile two-step strategy has been designed to prepare high performance bi-transition-metals (Fe- and Mo-) carbide supported on nitrogen-doped graphene (FeMo-NG) as electrocatalysts for oxygen reduction reactions (ORR). The as-synthesized FeMo carbide -NG catalysts exhibit excellent electrocatalytic activities for ORR in alkaline solution, with high onset potential (−0.09 V vs. saturated KCl Ag/AgCl), nearly four electron transfer number (nearly 4) and high kinetic-limiting current density (up to 3.5 mA cm−2 at −0.8 V vs. Ag/AgCl). Furthermore, FeMo carbide -NG composites show good cycle stability and much better toxicity tolerance durability than the commercial Pt/C catalyst, paving their application in high-performance fuel cell and lithium-air batteries.
Highlights
Catalysts for the oxygen reduction reaction (ORR) have attracted a great deal of attention because they play an important role in various energy conversion and storage devices, such as fuel cells, water splitting and lithium-air batteries, etc[1,2,3,4,5]
The FeMo carbide/NG hybrid composites exhibit good electrocatalytic activity, cycling stability and toxic tolerance for oxygen reduction reaction in alkaline solution, which are attributed to the synergic effect between well-dispersed carbide species and N-doped graphene
The field emission scanning electron microscopy (FESEM) (Fig. 2a,b) and transmission electron microscopy (TEM) (Fig. 2c) of FeMo Carbide/NG-800 which was the sample synthesized at 800 oC with the Fe:Mo molar ratio of 1:1 clearly reveal the uniform distribution of nanopraticles with size between 5 and 20 nm on graphene sheets
Summary
Catalysts for the oxygen reduction reaction (ORR) have attracted a great deal of attention because they play an important role in various energy conversion and storage devices, such as fuel cells, water splitting and lithium-air batteries, etc[1,2,3,4,5]. It is highly desirable to develop alternative no-precious metal catalysts with high oxygen reduction reaction activity[6,10]. N-doped graphene (NG) has been reported to be good catalyst as well as good support for ORR because of its large surface area, high electric conductivity, and nitrogen-related active sites[22,29,30,31,32]. Hybrid materials consisting of the transition metal carbides nanoparticles directly grown on the surface of N-doped graphene support would be promising catalyst with improved catalytic performance for ORR. The FeMo carbide/NG hybrid composites exhibit good electrocatalytic activity, cycling stability and toxic tolerance for oxygen reduction reaction in alkaline solution, which are attributed to the synergic effect between well-dispersed carbide species and N-doped graphene
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