High-performance hydrogen energy generation via innovative metal-organic framework catalysts and integrated system design.

Hydrogen energy generation faces challenges in efficiency and economic viability due to reliance on scarce noble metal catalysts. This study aimed to develop platinum-doped nickel-iron metal-organic framework (Pt-NiFe-MOF) catalysts with controlled metal ratios and pore architecture for enhanced water electrolysis. The NiFe-MOF framework was first synthesized via a solvothermal method, which was then subjected to post-synthetic modification to introduce controlled platinum loadings (0.5-2.0 wt%). The pore structure was tuned using a mixed-linker strategy (H₄DOBDC ratios 1:0 to 1:1). Catalysts were characterized using PXRD, HRTEM, BET, XPS, and ICP-OES techniques. Electrochemical performance was analyzed in 1.0 M KOH. A custom-designed integrated electrolysis system at 75 °C assessed practical performance. The Pt-NiFe-MOF-1.0 catalyst with H₄DOBDC ratio of 1:0.5 achieved remarkable effectiveness, requiring overpotentials of only 253 mV for OER and 58 mV for HER when operating at 10 mA/cm². This catalyst featured an optimal pore diameter of 4.2 nm and surface area of 1325 m²/g. DFT calculations revealed platinum incorporation created synergistic effects by modifying hydrogen binding energies. Furthermore, DFT calculations and XPS analysis revealed that the role of platinum in the OER is not direct catalysis, but rather a powerful electronic modulation effect; Pt dopants withdraw electron density from adjacent Ni and Fe centers, promoting the formation of higher-valent Ni³⁺/Fe³⁺ species that are intrinsically more active and lowering the energy barrier for the rate-determining O-O bond formation step. The integrated system achieved 1.62 V at 100 mA/cm² with 75.8% energy efficiency, maintaining stability for 200 h with 15-30 times lower precious metal loading than conventional systems. Strategic incorporation of low platinum concentrations within optimized NiFe-MOF structures significantly enhances water electrolysis performance while maintaining economic viability, advancing development of industrial-scale hydrogen generation systems.