High-efficiency Electroreduction of O into H O over ZnCo Bimetallic Triazole Frameworks Promoted by Ligand Activation.

Co-based metal-organic frameworks (MOFs) as electrocatalysts for two-electron oxygen reduction reaction (2e ORR) are highly promising for H O production, but suffer from the intrinsic activity-selectivity trade-off. Herein, we report a ZnCo bimetal-triazole framework (ZnCo-MTF) as high-efficiency 2e ORR electrocatalysts. The experimental and theoretical results demonstrate that the coordination between 1,2,3-triazole and Co increases the antibonding-orbital occupancy on the Co-N bond, promoting the activation of Co center. Besides, the adjacent Zn-Co sites on 1,2,3-triazole enable an asymmetric "side-on" adsorption mode of O , favoring the reduction of O molecules and desorption of OOH* intermediate. By virtue of the unique ligand effect, the ZnCo-MTF exhibits a 2e ORR selectivity of ≈100 %, onset potential of 0.614 V and H O production rate of 5.55 mol g  h , superior to the state-of-the-art zeolite imidazole frameworks. Our work paves the way for the design of 2e ORR electrocatalysts with desirable coordination and electronic structure.