Bimetallic metal-organic framework derived doped carbon nanostructures as high-performance electrocatalyst towards oxyge
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partment of Chemical and Materials Engineering, Concordia University, Montreal, Quebec H3G 1M8, Canada Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, Quebec H3G 1M8, Canada 3 Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada 2
© Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Received: 16 September 2020 / Revised: 16 October 2020 / Accepted: 26 October 2020
ABSTRACT Rational design and development of cost-effective, highly active and durable bifunctional electrocatalysts towards oxygen redox reactions is of critical importance but great challenge for the broad implementation of next-generation metal-air batteries for electric transportation. Herein, a high-performance electrocatalyst of cobalt and zinc sulfides nanocrystals embedded within nitrogen and sulfur co-doped porous carbon is successfully designed and derived from bimetallic metal-organic frameworks of cobalt and zinc containing zeolitic imidazolate frameworks. The unique nanostructure contains abundant electrocatalytic active sites of sulfides nanocrystals and nitrogen and sulfur dopants which can be fast accessed through highly porous structure originate from both zinc vaporization and sulfurization processes. Such bifunctional electrocatalyst delivers a superior half-wave potential of 0.86 V towards oxygen reduction reaction and overpotential of 350 mV towards oxygen evolution reaction, as well as excellent durability owing to the highly stable carbon framework with a great graphitized portion. The performance boosting is mainly attributed to the unique nanostructure where bimetallic cobalt and zinc provide synergistic effect during both synthesis and catalysis processes. The design and realization pave a new way of development and understanding of bifunctional electrocatalyst towards clean electrochemical energy technologies.
KEYWORDS bimetallic metal-organic frameworks, carbon nanostructures, electrocatalysts, oxygen redox reactions, nitrogen and sulfur doping
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Introduction
An exponential growth of energy consumption results in the fast depletion of fossil fuels and severe deterioration of environment, which in turn stimulates the discovery and development of renewable and sustainable energy technologies [1]. Over the past decades, electrochemical energy storage and conversion systems have been emerging as the most promising candidate in renewable energy sector, including fuel cells, rechargeable lithium-ion batteries (LIBs) and supercapacitors, etc. [2]. Particularly, metal-air batteries are widely believed to be the next-generation power source due to their high theoretical energy density often a magnitude greater than that of LIBs, abundant feed (air), as well as reliable and safe operations [3]. However, their implementation towards electric vehicles and grid storage applications is still hindered by the inherently sluggish kinetics and consequent high overpotential and complex multiple reactions [4].
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