Linker-Compensated Metal-Organic Framework with Electron Delocalized Metal Sites for Bifunctional Oxygen Electrocatalysis.

Metal-organic frameworks with tailorable coordination chemistry are propitious for regulating catalytic performance and deciphering genuine mechanisms. Herein, a linker compensation strategy is proposed to alter the intermediate adsorption free energy on the Co-Fe zeolitic imidazolate framework (CFZ). This grants zinc-air battery superior high current density capability with a small discharge-charge voltage gap of 0.88 V at 35 mA cm-2 and an hourly fading rate of less than 0.01% for over 500 h. Systematic characterization and theoretical modeling reveal that the performance elevation is closely correlated with the compensation of CFZ unsaturated metal nodes by S-bridging heterogeneous linkers, which exhibit electron-withdrawing characteristic that drives the delocalization of d-orbital electrons. These rearrangements of electronic structures establish a favorable adsorption/desorption pathway for key intermediates (OH*) and a stable coordination environment in bifunctional oxygen electrocatalysis.