Origin of Enhanced Oxygen Evolution in Restructured Metal–Organic Frameworks for Anion Exchange Membrane Water Electrolysis

Abstract

Metal–Organic Frameworks (MOFs), praised for structural flexibility and tunability, are prominent catalyst prototypes for exploring oxygen evolution reaction (OER). Yet, their intricate transformations under OER, especially in industrial high-current environments, pose significant challenges in accurately elucidating their structure–activity correlation. Here, we harnessed an electrooxidation process for controllable MOF reconstruction, discovering that Fe doping expedites Ni(Fe) MOF structural evolution, accompanied by the elongation of Ni−O bonds, monitored by in situ Raman and UV/Visible spectroscopy. Theoretical modeling further reveals that Fe doping and defect-induced tensile strain in the NiO₆ octahedra augments the metal ds-O p hybridization, optimizing their adsorption behavior and augmenting OER activity. The reconstructed Ni(Fe) MOF, serving as the anode in anion exchange membrane water electrolysis, achieves a noteworthy current density of 3300 mA cm⁻² at 2.2 V while maintaining equally stable operation 500 mA cm⁻² for 300 h and 1000 mA cm⁻² for 170 h. This undertaking elevates our comprehension of OER catalyst reconstruction, furnishing promising avenues for designing highly efficacious catalysts across electrochemical platforms.