Cobalt Nanoparticles Embedded in N-Doped Carbon Nanotubes on Reduced Graphene Oxide as Efficient Oxygen Catalysts for Zn-Air Batteries

Abstract

The key point to developing green and environmentally friendly zinc-air batteries is exploring efficient bifunctional electrocatalysts for oxygen reduction and evolution reactions (ORR and OER) on an air electrode. Herein, we reported a facile and green method for fabricating a bifunctional electrocatalyst of Co@N-CNT/rGO, which is composed of cobalt nanoparticles wrapped into nitrogen-doped carbon nanotubes growing on reduced graphene oxide. It is obtained by pyrolyzing a GO-wrapped two-dimension leaf-like zeolitic imidazolate framework. The Co@N-CNT/rGO-0.1 exhibits efficient catalytic activities for ORR and OER with a small Tafel slope. It benefits from the synergistic effect of the Co nanoparticle and N-CNT, the high conductivity of reduced graphene oxide and highly graphitizing carbon nanotubes, the great specific surface area, and suitable aperture size. Moreover, the Co@N-CNT/rGO-0.1 catalyst assembled primary zinc-air battery shows a high open-circuit voltage (1.43 V), a large peak power density (122 mW cm–2), and an excellent specific capacity (855 mA h gZn –1). In addition, the Co@N-CNT/rGO-0.1 assembly rechargeable zinc-air battery also displays an excellent cycling durability of 120 h at 5 mA cm–2. According to the above results, our work provides a cost-effective strategy to scale-up and commercialize the bifunctional electrocatalysts for zinc-air battery application.

CoNi Nanoalloys @ N-Doped Graphene Encapsulated in N-Doped Carbon Nanotubes for Rechargeable Zn–Air Batteries

“…The 2D band belongs to the typical graphitic carbon peak, indicating that the carbon nanostructures in CN@NC–2–800 could provide good electrical conductivity. Except for N@NC, other materials exhibit a peak at ∼661 cm –1 , which is the representative vibration from the A 1g mode of Co–Co stretching . Compared with C@NC, the intensity of the peak at ∼661 cm –1 for CN@NC– n – T samples appears weaker, which is ascribed to the formation of CoNi nanoalloys, weakening the characteristic peak of monometallic Co.…”

“…Except for N@NC, other materials exhibit a peak at ∼661 cm −1 , which is the representative vibration from the A 1g mode of Co−Co stretching. 35 Compared with C@NC, the intensity of the peak at ∼661 cm −1 for CN@NC−n−T samples appears weaker, which is ascribed to the formation of CoNi nanoalloys, weakening the characteristic peak of monometallic Co. The specific surface areas and pore structures of the CN@NC−2−800, C@NC, and N@NC were investigated by the N 2 adsorption− desorption measurements (Figure 3d).…”

Recent progress in metal–organic framework/graphene-derived materials for energy storage and conversion: design, preparation, and application

“…132,137,175,177 In recent years, more efforts have been devoted to the development of efficient and stable bifunctional oxygen electrocatalysts due to their practicability. Up to now, various highactivity catalysts based on MOF/graphene composites, including M-N-C, 245,246 bimetallic suldes, 92,152 metal nitrides, 179,181 and metal oxides and carbides, 94,178 showed great advantages and application potentials for the OER and ORR. In particular, cobalt-based nitride/graphene hybrids have attracted much attention because of their tailored electronic conguration of Co sites coordinated by N atoms and high inherent persite catalytic activity.…”

Carbon Nanofibers as Potential Catalyst Support for Fuel Cell Cathodes: A Review

“…Among all carbon supports, graphitic carbon nanofibers (GNFs), sometimes also termed as carbon nanofibers (CNFs), have received great attention as catalyst support material due to (i) their unique fibrous structure, (ii) their highly graphitic nature, (iii) the unique interaction of the deposited metal nanoparticles with the nanofiber surface, (iv) the attainment of specific crystallographic orientation of supported metal nanoparticles, (v) their excellent electronic conducting properties, and (vi) the lower susceptibility of the deposited nanoparticles toward CO poisoning, in comparison with traditional catalyst systems. − The carbon nanofibers are synthesized by the two most popular synthesis methods: (i) chemical vapor deposition (CVD) , and (ii) electrospinning. − The nanofibers synthesized by these two methods differ in many ways, including morphology, graphitization, electrical conductivity, graphene layer arrangement, and synthesis conditions themselves. Hence, this Review is limited to the nanofibers synthesized by the CVD method.…”

“…Considerable research has been undertaken in the past decade to discover alternative, cost-effective ORR catalysts made up of transition metals such as Fe, Co, Ni, and Mn, especially in combination with the N-doped carbons, which generate potentially ORR active sites, namely M-N-C. − S. G. Peera et al synthesized a durable GNF catalyst by the deposition of Fe and Co species on the N-F/GNF catalysts (Fe-Co/NF-GNF). The GNFs transformed to graphene structures and the metallic nanoparticles were encapsulated by the N-F graphene layers.…”