Unveiling dynamic surface transformations: Mo-doped Fe-based MOFs as next-generation oxygen evolution catalysts

Abstract

Unlocking the full potential of metal–organic frameworks (MOFs) for water-splitting applications requires innovative strategies to enhance their catalytic efficiency and stability. Here, we introduce a Mo-doped Fe-based MOF (MoFe-NH₂-BDC) with a unique 2D nanosheet and plate-like morphology to revolutionize the oxygen evolution reaction (OER). Mo incorporation optimizes electronic properties, accelerates charge transfer, and dynamically reconstructs the catalyst surface into highly active FeOOH species, ensuring long-term performance. This next-generation electrocatalyst achieves an ultra-low overpotential of 254 mV at 20 mA cm⁻², with a rapid Tafel slope of 66 mV dec⁻¹, surpassing conventional RuO₂ catalysts. Operando Raman and ATR-FTIR spectroscopy reveal that Mo facilitates an adsorbate evolution mechanism (AEM), stabilizing intermediates and boosting reaction kinetics. In a practical two-electrode system, MoFe-NH₂-BDC⁽⁺⁾||Pt/C⁽⁻⁾ demonstrates an exceptional cell voltage of 1.58 V at 100 mA cm⁻², maintaining stability for 85 h. These results underscore the transformative impact of Mo doping in MOFs, paving the way for highly efficient, durable, and scalable electrocatalysts for sustainable energy applications.