MOF-assisted synthesis of Ni, Co, Zn, and N multidoped porous carbon as highly efficient oxygen reduction electrocatalysts in Zn–air batteries

Abstract It is an urgent demand to develop cost-effective and efficient non-noble metal electrocatalysts for oxygen reduction reaction (ORR), the key cathodic reaction of fuel cells and metal–air batteries. In this regard, we herein propose a one-pot strategy to produce porous carbon electrocatalysts multidoped by nickel (Ni), cobalt (Co), zinc (Zn), and nitrogen (N). Typically, appropriate metal precursors are aged with 2-methylimidazole in methanol to obtain Ni and Co co-doped Zn-based zeolitic imidazolate frameworks (Ni-Co-ZIF-8) for the final formation of Ni, Co, Zn, and N multi-doped porous carbon (Ni-Co-Zn-N-PC) through pyrolysis, in which cavities and pores are created because of the Zn evaporation at high temperature, while the Co-N bonds in Ni-Co-ZIF-8 could be inherited. The cavities, Co-N active sites and additional synergies among different metals that improve the electrical conductivity of the catalyst collectively promote the ORR catalytic performance of Ni-Co-Zn-N-PC. In specific, the as-prepared Ni-Co-Zn-N-PC features favorable ORR electrocatalysis in a half-wave potential of ca. 0.864 V, limited current density of ca. 6.40 mA cm−2, superior long-term stability, and strong anti-interference to methanol. In addition, a zinc–air battery using Ni-Co-Zn-N-PC as air-cathode catalyst exhibits good performances in terms of open-circuit voltage, power density, specific capacity, and durability, suggesting its promise in practical energy conversion devices.