N,S-Codoped hierarchical porous carbon spheres embedded with cobalt nanoparticles as efficient bifunctional oxygen electrocatalysts for rechargeable zinc-air batteries

Xiaojing Zhu; Jiale Dai; Ligui Li; Zexing Wu; Shaowei Chen

doi:10.1039/c9nr07632h

N,S-Codoped hierarchical porous carbon spheres embedded with cobalt nanoparticles as efficient bifunctional oxygen electrocatalysts for rechargeable zinc-air batteries

Nanoscale. 2019 Nov 28;11(44):21302-21310. doi: 10.1039/c9nr07632h. Epub 2019 Oct 31.

Authors

Xiaojing Zhu¹, Jiale Dai¹, Ligui Li², Zexing Wu³, Shaowei Chen⁴

Affiliations

¹ New Energy Research Institute, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, China. esguili@scut.edu.cn.
² New Energy Research Institute, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, China. esguili@scut.edu.cn and Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510641, China and State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China.
³ State Key Laboratory Base of Eco-chemical Engineering, College of Chemistry and Molecular Engineering, Qingdao University of Science & Technology, No. 53 Zhengzhou Road, 266042, Qingdao, China.
⁴ New Energy Research Institute, School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, 510006, China. esguili@scut.edu.cn and Department of Chemistry and Biochemistry, University of California, 1156 High street, Santa Cruz, California 95064, USA. shaowei@ucsc.edu.

PMID: 31670323
DOI: 10.1039/c9nr07632h

Abstract

Rational design and fabrication of cost-effective, efficient bifunctional electrocatalysts is fundamentally important for the air cathode of metal-air batteries. Herein, a Co(ii) ion-driven self-assembly strategy is described for the synthesis of cobalt-based nanostructured transition metal compounds (Co-NTMCs) embedded in nitrogen and sulfur codoped hierarchical porous carbon submicrospheres (Co-NTMCs@NSC), where condensation of thiourea-ethylenediamine-formaldehyde resin (TEFR) is induced by Co(ii) ions which is simultaneously assembled with polydopamine to form a multifunctional precursor through coordinated interaction. The resulting Co-NTMCs@NSC sample comprises abundant hierarchical porous textures, a high content of active cobalt species including the nanoparticles of Co, Co₃O₄ and amorphous CoS_x, and a considerable amount of defective structures. These characteristics lead to remarkable oxygen electrocatalytic activities, with a half-wave potential of +0.833 V vs. RHE, which is comparable to that of commercial Pt/C for the oxygen reduction reaction (ORR), and a lower overpotential of 284 mV than RuO₂ at 10 mA·cm^-2 for the oxygen evolution reaction (OER) in alkaline media. Furthermore, its operational stability is also much higher than that of commercial RuO₂ and Pt/C catalysts. When used as a breathing air electrode for Zn-air batteries, Co-NTMCs@NSC shows a higher open-circuit voltage (1.509 V), higher discharge power density (262 mW cm^-2) and better charge-discharge reversibility than commercial Pt/C. The results from the present work suggest that controlled assembly of functional polymers may be exploited for the preparation of doped carbon/metal nanoparticle nanocomposites as viable, high-performance catalysts for electrochemical energy technologies.