Bimetal-phthalocyanine based covalent organic polymers for highly efficient oxygen electrode

Abstract

The feature of tunable constituents in covalent organic polymers (COPs) via combination of predesigned building units is of great interest in exploring multi-functional catalysts. Here, we report constituent-tunable metal-phthalocyanine-based covalent organic polymers as self-sacrificial precursors for fabrication of mono- (Fe or Ni) and bi-metallic (Fe-Ni) heteroatoms/carbon catalysts toward both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). As a result, the as-prepared FeNi-COP-800 exhibits an efficient ORR performance with a half-potential of 0.80 V as well as an IrO2-like OER activity with a potential of 1.63 V at 10 mA cm−2, which surpass those of monometallic Fe-COP-800 and Ni-COP-800. Moreover, a zinc-air flow battery using FeNi-COP-800 catalyst not only shows a higher power density than the battery using Pt/C-IrO2/C but also displays superior stability with 2.90% potential loss after 85 cycles in 175 h of practical operation. Accordingly, this work provides a facile but efficient approach in molecular incorporation of desired constituents to obtain bi/multi-active sites in a single catalyst for various catalytic roles, including, but not limited to, oxygen reduction, hydrogen evolution, oxygen evolution.