MOF-derived Co, Fe, and Ni co-doped N-enriched hollow carbon as efficient electrocatalyst for oxygen reduction reaction

In this study, we have successfully prepared Co, Fe, and Ni co-doped and N-enriched hollow carbon (CoFeNi/NC) via a facile corrosion, pyrolysis, and replacement method, to be used as an oxygen reduction reaction (ORR) electrocatalyst. The structure of polyvinylpyrrolidone/zeolitic imidazolate framework-8/zeolitic imidazolate framework-67 (PVP/ZIF-8/ZIF-67) can be etched by Ni2+ during the hydrolysis process, and the resultant Zn metal can be removed by Fe2+ via a replacement reaction method. The addition of Fe and Ni enhances the graphitization degree and the specific surface area of the electrocatalyst. Furthermore, the electrocatalytic performance of the as-synthesized samples were carefully investigated. Fe and Ni can substantially enhance the ORR activity of the electrocatalyst. Compared to the CoZn/NC, CoFeNi/NC shows enhanced ORR performance, high current density (2.593 mA cm−2), and superior onset potential (0.914 V). Moreover, CoFeNi/NC can effectively avoid ORR performance decay, and hence an excellent long-term operational stability can be achieved.