Hierarchically Porous Mn-Cu Bimetallic Catalysts Derived From Dopamine-Modified ZIF for Oxygen Reduction and Zinc-Air...

Carbon-based non-precious-metal electrocatalysts have emerged as promising alternatives to precious-metal catalysts for the oxygen reduction reaction (ORR). Rational regulation of the electronic structure and local coordination environment is crucial for improving catalytic performance. In this paper, the Mn-Cu bimetallic electrocatalyst with high ORR activity is successfully developed. The catalyst possesses a rich porous structure with strong Mn-Cu synergism. It exhibits an onset potential of 1.15 V and a half-wave potential of 0.88 V, as well as a high limiting current density (5.65 mA cm^-2) and a low Tafel slope (92 mV dec^-1) for ORR. Systematic investigation of the Mn/Cu ratio reveals that increasing the ratio of Mn to Cu can further improve the kinetic performance, while decreasing the ratio of Mn to Cu increases the limiting current density. The density functional theory calculations reveal that Mn-Cu synergism modulates the adsorption properties of the active sites, thus improving the ORR performance. Furthermore, a rechargeable zinc-air battery based on MnCu@D delivers a high power density of 227 mW cm^-2 and excellent cycling stability exceeding 200 h. This work will help to promote the development and application of novel bimetallic catalysts for zinc-air batteries.