ScholarWorks@동국대학교

초록

Efficient electrochemical water splitting hinges on the development of robust catalysts that enhance both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) kinetics. In this work, a series of bimetallic NiMn-based bimetallic metal-organic frameworks (MOFs) integrated with NiMnCr LDH were synthesized, with precise control over chromium content. The NiMn MOF/NiMnCr LDH0.005 (NM MOF/NMC LDH0.005) composite demonstrated superior bifunctional electrocatalytic activity toward HER, OER, and urea oxidation reaction (UOR) with low overpotentials and favorable Tafel slopes. The NM MOF/NMC LDH0.005 electrocatalyst exhibits the best electrocatalytic activity with very low overpotentials of 370.3 mV for OER (at 100 mA cm- 2 current density), 215.9 mV for HER (at 10 mA cm- 2 current density), and 1.42 V for UOR (at 100 mA cm- 2 current density). This catalyst exhibited outstanding charge transfer kinetics, large electrochemically active surface area, and remarkable stability over prolonged operation. The NM MOF/NMC LDH0.005 hybrid also enabled energy-efficient hydrogen production in a two-electrode urea electrolyzer configuration by achieving a cell potential corresponding to E10 = 1.65 V, highlighting its practical applicability. Detailed structural, spectroscopic, and electrochemical analyses reveal that synergistic interfacial interactions, optimized electronic structures, and hierarchical nanostructures drive the exceptional catalytic performance.

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