Modulating Host–Guest Interactions in Isoreticular Fe(III)-Doped Co-MOF Precatalysts for Electrocatalytic Oxygen Evolution

The pursuit of sustainable energy solutions to address environmental challenges and energy crises has driven significant interest in electrocatalytic water splitting. However, the efficiency of this process is hindered by the sluggish kinetics of the anodic oxygen evolution reaction (OER). To overcome this, we synthesized two isoreticular cobalt-based metal-organic frameworks (MOFs), MOF-74 and MOF-274, with different pore sizes (16.50 and 23.37 Å, respectively), where MOF-74 exhibited stronger Fe(III) adsorption as a result of its confined nanosized channels. Electrochemical activation transformed these Co-MOF precatalysts into Fe-doped CoOOH nanosheets with uniform elemental distribution, enhancing their OER performance. It revealed strengthened Co-O-Fe electronic interactions in MOF-74-Fe by X-ray photoelectron spectroscopy analysis, where MOF-74-Fe-OER achieved a decent electrocatalytic OER activity to show a lower overpotential of 288 mV at 10 mA cm^-2 compared to MOF-274-Fe-OER (357 mV). Furthermore, the long-term stability tests confirmed robust durability, with MOF-74-Fe-OER retaining 96.9% of its initial performance over 10 h. These results underscore the critical role of pore-engineered MOF precatalysts in optimizing electronic modulation and catalytic efficiency for sustainable water oxidation.