Exceptional Long-Term Stability in Hydrogen Evolution via Defect-Engineered MIL-100 Synthesized by Controlled...

Area of Science:

• Materials Science
• Catalysis
• Chemical Engineering

Background:

• Metal-organic frameworks (MOFs) are promising catalysts.
• Defect engineering in MOFs can enhance catalytic properties.
• Hydrogen generation from NaBH₄ hydrolysis is an important energy application.

Purpose of the Study:

• To prepare and characterize quasi-iron-based MOFs (Q-MIL-100 and Q-MIL-101) with engineered defects.
• To investigate their performance in catalytic hydrogen generation from NaBH₄ hydrolysis.
• To understand the structure-activity relationships and stability of these catalysts.

Main Methods:

• Synthesis of Q-MIL-100 and Q-MIL-101 via thermal partial deligandation.
• Catalytic testing for hydrogen generation from NaBH₄ hydrolysis at different temperatures.
• Kinetic studies including activation energy and kinetic isotope effect.
• Stability testing over multiple reuse cycles.

Main Results:

• Engineered MOFs (Q-MIL-100, Q-MIL-101) exhibited enhanced unsaturated iron sites and hierarchical porosity.
• Q-MIL-100 showed a superior hydrogen generation rate (5360 mL·min⁻¹·g⁻¹) at 298 K compared to Q-MIL-101 (3360 mL·min⁻¹·g⁻¹).
• Rates increased significantly at 313 K, with Q-MIL-100 achieving 12,160 mL·min⁻¹·g⁻¹.
• Q-MIL-100 demonstrated excellent stability, retaining 92% activity after 16 cycles, with low activation energy (41.7 kJ·mol⁻¹).

Conclusions:

• Defect engineering in iron-based MOFs effectively enhances catalytic activity for hydrogen generation.
• Q-MIL-100 presents a highly active and stable catalyst for practical hydrogen production.
• The O-H bond cleavage in water is the rate-determining step.