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-Op 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 3.3 A cm-2 at 2.2 V while maintaining equally stable operation for 160 h spanning from 0.5 A cm-2 to 1 A cm-2. This undertaking elevates our comprehension of OER catalyst reconstruction, furnishing promising avenues for designing highly efficacious catalysts across electrochemical platforms.