Leveraging ligand push-pull effects in Ni-based MOFs for optimized lattice oxygen activation and superior water oxidation

Understanding the oxygen evolution reaction (OER) mechanism is critical for the rational design of high-performance OER electrocatalysts. Theoretically, the lattice oxygen oxidation mechanism (LOM) bypassing the inherent limitations of the traditional adsorbate evolution mechanism through direct interactions between lattice oxygen and oxygen intermediates, thereby lowering the energy barrier of alkaline OER. However, effective lattice oxygen activation remains a significant challenge. Herein, a Ni-based metal-organic framework, Ni N x F 10-x , was employed as a model system to precisely regulate the local microenvironment around the Ni active site via the push-pull effect of organic ligand side groups, thus achieving an efficient LOM pathway. Experimental results demonstrated that this electronic push-pull effect induced lattice strain and morphology variations in Ni N x F 10-x , driven to generate more unsaturated metal sites. The optimized Ni N 3 F 7 /CP exhibited excellent OER activity, achieving a low overpotential of 213 mV at 10 mA cm⁻² and long-term stability in 1.0 M KOH. In-situ electrochemical impedance spectroscopy, in-situ Raman, DEMS and density functional theory calculations combined to illustrate that this ligand functionalization significantly benefited the LOM pathway and OER performance by optimizing intermediate adsorption. This work provides a new perspective for developing advanced OER catalysts.