An Isolated Zinc-Cobalt Atomic Pair for Highly Active and Durable Oxygen Reduction

A competitive complexation strategy has been developed to construct a novel electrocatalyst with Zn-Co atomic pairs coordinated on N doped carbon support (Zn/CoN-C). Such architecture offers enhanced binding ability of O-2, significantly elongates the O-O length (from 1.23 angstrom to 1.42 angstrom), and thus facilitates the cleavage of O-O bond, showing a theoretical overpotential of 0.335 V during ORR process. As a result, the Zn/CoN-C catalyst exhibits outstanding ORR performance in both alkaline and acid conditions with a half-wave potential of 0.861 and 0.796 V respectively. The in situ XANES analysis suggests Co as the active center during the ORR. The assembled zinc-air battery with Zn/CoN-C as cathode catalyst presents a maximum power density of 230 mWcm(-2) along with excellent operation durability. The excellent catalytic activity in acid is also verified by H-2/O-2 fuel cell tests (peak power density of 705 mWcm(-2)).