Hybrid Materials Containing Co Species Dispersed on Carbonized Frameworks and their Electrocatalytic Properties for O2 reduction

Abstract

The oxygen reduction reaction (ORR), occurred at cathodes in fuel cells, eco-friendly energy-conversion system, requires efficient electrocatalysts to overcome sluggish reaction kinetics. In this work, to enhance the ORR performance by decreasing potentials, we developed carbonized zeolite-imidazolate frameworks (ZIF) containing Co atoms (Co–C). The final product is produced by two-step process including (i) the formation of ZIF with Co species, and (ii) carbonization of the ZIF using high temperature treatment. Morphological characterizations revealed that the Co–C has polygon-shaped ZIF-based materials with metallic Co particles wrapped by layered carbon structures. The amount of Co atoms is found to be ~ 4 wt%, possessing a large surface area of 718 m²/g. X-ray photoelectron spectroscopy measurements further supported the formation of sp² carbon structures with N-doping. The Co–C products exhibit an efficient electrocatalytic ORR performance in alkaline media, with their onset and half-wave potentials as of 0.97 and 0.86 V, comparable to those of Pt/C. Furthermore, Co–C shows the excellent cyclic durability and stability against for methanol poisoning. Collectively, this system including Co-based active species on ZIF networks provides a promise route for the development of efficient ORR electrocatalysts.