Designing bifunctional catalysts for oxygen reduction/evolution reactions for high efficiency and long lifetime. (1st August 2019)

• Record Type: Journal Article
• Authors: Lingappan, Niranjanmurthi; Li, Bing; Lee, Tae Hoon; Lee, Young Hee
• Is Part Of: Electrochimica acta. Volume 313(2019)
• Page Start: 41
• Page End: 47
• Publication Date: 2019-08-01
• Subjects: Self-assembly -- Spinel metal oxides -- Bifunctional catalyst -- Oxygen reduction reaction -- Oxygen evolution reaction; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2019.04.176
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: Designing efficient and durable bifunctional oxygen catalyst to replace expensive Pt catalysts in oxygen reduction reaction and oxygen evolution reaction is crucial for various energy conversion devices, such as metal-air batteries and fuel cells. Although various nanocarbon/metal oxides have been developed, their catalytic efficiencies remain unsatisfactory; moreover, bi-functionality and the issue of long-term durability have remained elusive goals. Herein, we report the self-assembly of interconnected nickel-cobaltite nanocrystals on nitrogen-doped graphene via hydrothermal synthesis. The Co 3+ sites, the key radicals for bifunctional oxygen reduction and evolution reactions. Well-dispersed nitrogen-doped graphene serve as a platform for anchoring the interconnected nickel-cobaltite nanocrystals and improve the conductivity to maintain a high saturation current in oxygen reduction and low overpotential in evolution reaction, similar to Pt/C. Lifetimes as long as 200 h for oxygen reduction and 300 h for oxygen evolution are demonstrated with negligible degradations. The present approach paves the way for the rational design of various Gr-metal oxide hybrids for numerous applications. Graphical abstract: Image 1 Highlights: Interconnected i -NiCo2 O4 grown on nitrogen-doped graphene via self-assembly strategy. The interconnected nanostructure prevented the migration of nanoparticles. The electrocatalytic activity was evaluated in oxygen reduction/evolution reactions. The hybrid exhibited high catalytic activity and long term durability.