Green Energy & Environment (Feb 2023)

Micropores regulating enables advanced carbon sphere catalyst for Zn-air batteries

  • Jingsha Li,
  • Shijie Yi,
  • Ranjusha Rajagopalan,
  • Zejie Zhang,
  • Yougen Tang,
  • Haiyan Wang

Journal volume & issue
Vol. 8, no. 1
pp. 308 – 317

Abstract

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Energy conversion technologies like fuel cells and metal-air batteries require oxygen reduction reaction (ORR) electrocatalysts with low cost and high catalytic activity. Herein, N-doped carbon spheres (N-CS) with rich micropore structure have been synthesized by a facile two-step method, which includes the polymerization of pyrrole and formaldehyde and followed by a facile pyrolysis process. During the preparation, zinc chloride (ZnCl2) was utilized as a catalyst to promote polymerization and provide a hypersaline environment. In addition, the morphology, defect content and activity area of the resultant N-CS catalysts could be regulated by controlling the content of ZnCl2. The optimum N-CS-1 catalyst demonstrated much better catalytic activity and durability towards ORR in alkaline conditions than commercial 20 wt% Pt/C catalysts, of which the half-wave potential reached 0.844 V vs. RHE. When applied in the Zn-air batteries as cathode catalysts, N-CS-1 showed a maximum power density of 175 mW cm−2 and long-term discharging stability of over 150 h at 10 mA cm−2, which outperformed 20 wt% Pt/C. The excellent performance could be due to its ultrahigh specific surface area of 1757 m2 g−1 and rich micropore channels structure. Meanwhile, this work provides an efficient method to synthesize an ultrahigh surface porous carbon material, especially for catalyst application.

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