Self-etched bimetallic hybrid derived cobalt/zinc dual-sites coordinated N, P-codoped hollow carbon polyhedron for efficient oxygen reduction reaction

Abstract

Hollow structure with hierarchical pore is benefit for the exposure of active sites, showing great advantages in electrocatalysis. Whereas, it still a challenge for the target preparation of such architecture in a simple, but efficient ways. Herein, a Co/Zn-Nx (Nx represents the number of N atoms (x) coordinated with Co or Zn atoms) dual sites anchored N, P-codoped hollow carbon polyhedron (PZH-800) with well-defined Co species was facilely prepared via direct pyrolysis of a bimetallic hybrid (PZH) obtained by polymerization-coating of Zn-porphyrin polymer on the surface of zeolitic-imidazolate-framework (ZIF-67). The hollow architecture was formed via self-etching, in which the hydrochloric acid produced during the formation of hybrid etched the inner acid-degradable ZIF-67. Different with post-etching method, self-etching could really preserve the original structure and catalytic sites, better regulate the electronic structures, enhancing the catalytic activity. Compared with the Co or Zn mono-doped sample, PZH-800 presented an enhanced ORR activity with a half-wave potential (E1/2) of 0.94 V (vs. RHE), as well as outstanding stability, outperforming commercial Pt/C (20%) in alkaline media. Impressively, ZABs using PZH-800 as the cathodic catalyst demonstrated a maximum power density (280 mW cm−2), coupled with a remarkable running stability, surpassing the battery catalyzed by Pt/C. This work paves a new avenue for the future development of MOF-derived non-precious metal-based hollow catalysts.

Keywords

• ZIF-67 template
• Hybrid
• Hollow structure
• ORR
• Zn-air battery