Synthesis of Bimetallic Conductive 2D Metal-Organic Framework (CoxNiy-CAT) and Its Mass Production: Enhanced Electrochemical Oxygen Reduction Activity

The development of new electrocatalysts for electrochemical oxygen reduction to replace expensive and rare platinum-based catalysts is an important issue in energy storage and conversion research. In this context, conductive and porous metal-organic frameworks (MOFs) are considered promising materials for the oxygen reduction reaction (ORR) due to not only their high surface area and well-developed pores but also versatile structural features and chemical compositions. Herein, the preparation of bimetallic conductive 2D MOFs (CoxNiy-CATs) are reported for use as catalysts in the ORR. The ratio of the two metal ions (Co2+ and Ni2+) in the bimetallic CoxNiy-CATs is rationally controlled to determine the optimal composition of CoxNiy-CAT for efficient performance in the ORR. Indeed, bimetallic MOFs display enhanced ORR activity compared to their monometallic counterparts (Co-CAT or Ni-CAT). During the ORR, bimetallic CoxNiy-CATs retain an advantageous characteristic of Co-CAT in relation to its high diffusion-limiting current density, as well as a key advantage of Ni-CAT in relation to its high onset potential. Moreover, the ORR-active bimetallic CoxNiy-CAT with excellent ORR activity is prepared at a large scale via a convenient method using a ball-mill reactor.