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Electrocatalysis of both oxygen reduction and water oxidation using a cost-effective three-dimensional MnO₂/graphene/carbon nanotube
- Ye, Daixin, Wu, Tong, Cao, Hongmei, Wang, Yi, Liu, Baohong, Zhang, Song, Kong, Jilie
- RSC advances 2015 v.5 no.34 pp. 26710-26715
- carbon nanotubes, catalysts, catalytic activity, cathodes, chemical reduction, cost effectiveness, durability, electricity, electrochemistry, energy conversion, fuels, graphene, manganese dioxide, oxidation, oxygen, oxygen production, platinum, potassium hydroxide
- The electrochemical oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are of great interest since they are involved in energy conversion between fuel and electricity. Here, we developed a bifunctional MnO₂/graphene/carbon nanotube that is free of noble metals and that could be a promising candidate electrocatalyst for these oxygen reduction and evolution reactions. It was shown to be able to act as an efficient cathode catalyst for the ORR, having a positive half-wave potential that differs by only ∼55 mV from that of commercial Pt/C, and a high cathodic current density that is comparable to that of the Pt/C catalyst. Moreover, the hybrid exhibited superior durability with nearly no decay in ORR activity even after 10 000 s of continuous operation in 0.1 M KOH, while Pt/C shows a 20% decrease in the activity. Most importantly, the hybrid was also shown to be highly active for the OER. These observations show this hybrid to be a high-performance non-precious metal-based bi-catalyst for both the ORR and OER.