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.
Developing efficient bifunctional electrocatalysts with excellent oxygen reduction and evolution reaction (ORR/ OER) activity to meet practical demands in Zn−air batteries (ZABs) is highly crucial and challenging. Herein, a simple hydrothermal one-step method is exploited to successfully synthesize Co 3 O 4 −NiCo 2 O 4 anchored on N-doped reduced graphene oxide nanosheets (Co 3 O 4 −NiCo 2 O 4 /N-RGO). The active sites present in Co 3 O 4 −NiCo 2 O 4 /N-RGO and the synergy between N-RGO and Co 3 O 4 −NiCo 2 O 4 accelerate the charge transfer and transport rate during the electrochemical course, which improves the ORR/OER activities of the Co 3 O 4 −NiCo 2 O 4 / N-RGO electrocatalyst. As expected, the Co 3 O 4 −NiCo 2 O 4 /N-RGO exhibits a better half-wave potential in the ORR and a lower Tafel slope during the OER process. A ZAB with optimal Co 3 O 4 −NiCo 2 O 4 /N-RGO as the cathode gives a higher open-circuit voltage (1.49 V), larger power density (97 mW cm −2 ), and better stability (180 h).
Cobalt @ tunable N-doped graphene shells anchored on N-doped RGO is designed as an efficient pH-universal electrocatalyst. The superior performance is mainly attributed to the optimization of the electrocatalytic centre and electronic configuration.
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