Tuning Coordination Structures of Zn Sites Through Symmetry-Breaking Accelerates Electrocatalysis.

Manipulating the coordination environment of individual active sites in a precise manner remains an important challenge in electrocatalytic reactions. Herein, inspired by theoretical predictions, we present a facile procedure to synthesize a series of symmetry-breaking zinc metal-organic framework (Zn-MOF) catalysts with well-defined structures. Benefiting from the optimized coordination microenvironment regulated by symmetry-breaking, Zn-N 2 S 2 -MOF exhibits the best performance of N 2 reduction reaction (NRR) with NH 3 yield rate of 25.07 ± 1.57 µg h -1 cm -2 and Faradaic efficiency of 44.57 ± 2.79% compared with reported Zn-based NRR catalysts. X-ray absorption near-edge structure shows that the symmetry-breaking distorts the coordination environment and modulates the delocalized electrons around the Zn sites, which favors the formation of unpaired low-valence Zn δ+ , thereby facilitating the adsorption/activation of N 2 . Theoretical calculations elucidate that low-valence Zn δ+ in Zn-N 2 S 2 -MOF can effectively lower the energy barrier of potential determining step, promoting the kinetics and boosting the NRR activity. This work highlights the relationship between the precise coordination environment of metal sites and the catalytic activity, which offers insightful guidance for rationally designing high-efficiency electrocatalysts. This article is protected by copyright. All rights reserved.