Co-Doped [Ni(1-ipIM)3·B6O7(OH)6]·[H3BO3]·2.5H2O via In-Situ Pyrolysis Achieving CoNi Alloy Nanocrystals for High-Performance Zinc−Air Batteries

A series of CoNi bimetallic borates [NixCo1−x(1-ipIM)3·B6O7(OH)6]·[H3BO3]·3.5H2O (x = 0.9, 0.7, 0.5, 0.3) have been synthesized, in which the oxoboron clusters in the structure contain abundant hydrogen-bonding sites, which are prone to form an open framework and a supramolecular porous structure, providing sufficient free space for catalytic reactions. The borates were converted into CoNi alloy nanocrystals loaded on amorphous carbon via in-situ pyrolysis. Notably, these are the first CoNi alloy nanocrystal oxygen reduction reaction (ORR) catalysts derived from borate precursors that exhibited excellent ORR activity in alkaline media with a half-wave potential as high as 0.881 V, which is slightly better than commercial Pt/C. When applied in zinc−air batteries (ZABs), they exhibited outstanding electrochemical performance, especially a cycling stability of up to 800 h. The superior catalytic performance is attributed to the synergistic effect between Co and Ni, which provides ideas for the development of efficient borate-based ORR catalysts through multi-metallic synergy and promotes their application in high-performance ZABs.