Stepwise Fabrication of Co-Embedded Porous Multichannel Carbon Nanofibers for High-Efficiency Oxygen Reduction
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ARTICLE
Cite as Nano-Micro Lett. (2019) 11:33 Received: 19 February 2019 Accepted: 22 March 2019 © The Author(s) 2019
https://doi.org/10.1007/s40820-019-0264-2
Stepwise Fabrication of Co‑Embedded Porous Multichannel Carbon Nanofibers for High‑Efficiency Oxygen Reduction Zeming Tang1, Yingxuan Zhao1, Qingxue Lai1 *, Jia Zhong1, Yanyu Liang1,2 * * Qingxue Lai, [email protected]; Yanyu Liang, [email protected] Jiangsu Key Laboratory of Materials and Technology for Energy Conversion, College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, People’s Republic of China 2 Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites, Nanjing 211816, People’s Republic of China 1
HIGHLIGHTS • An interconnected structure is developed by evaporation of zinc species using a ZnCo2O4 precursor as the cobalt resource, enabling communications between channels as well as homogeneous loading of active sites. • A shell structure of Co3O4 is formed on the surface of a zero-valent Co0 core during a stepwise carbothermic reduction of ZnCo2O4. • The Co-embedded multichannel carbon nanofibers exhibit not only a superior half-wave potential, but also an excellent durability compared to those of the commercial 30% Pt/C.
ABSTRACT A novel nonprecious metal material consisting of Co-
embedded porous interconnected multichannel carbon nanofibers (Co/ IMCCNFs) was rationally designed for oxygen reduction reaction (ORR) electrocatalysis. In the synthesis, Z nCo2O4 was employed to form inter-
O2
connected mesoporous channels and provide highly active C o3O4/Co
4e−
core–shell nanoparticle-based sites for the ORR. The IMC structure with a large synergistic effect of the N and Co active sites provided fast ORR
electrocatalysis kinetics. The Co/IMCCNFs exhibited a high half-wave potential of 0.82 V (vs. reversible hydrogen electrode) and excellent stability with a current retention up to 88% after 12,000 cycles in a cur-
Co
OH−
3O 4
Co 10 nm
rent–time test, which is only 55% for 30 wt% Pt/C. KEYWORDS Nonprecious metal material; Multichannel carbon nanofiber; Oxygen reduction reaction; Core–shell nanoparticle; Synergistic effect
1 Introduction Fuel cells are considered as ideal alternatives to fossil fuels owing to their high energy conversion efficiencies and environmental friendliness. An H 2–O2 fuel cell exhibits a thermodynamic efficiency of approximately 80% at 25 °C, significantly higher than that of an internal combustion engine (10–20%)
[1–3]. Nevertheless, the sluggish kinetics of the oxygen reduction reaction (ORR) on the cathode hinder the large-scale industrial application of the fuel cells [4, 5]. Currently, Pt and Pt-based alloys exhibit superior electrocatalytic properties in acid and alkaline media. However, owing to the high costs and unsatisfactory stabilities of Pt and Pt-based alloys, it is required to develop cheap efficient ORR catalysts [6–9]. Vol.:(0123456789)
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Transition metal-based materials, su
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