Keggin-Type Polyoxometalate-Based ZIF-67 for Enhanced Photocatalytic Nitrogen Fixation

Area of Science:

• Materials Science
• Catalysis
• Green Chemistry

Background:

• Photocatalytic reduction of nitrogen (N2) to ammonia (NH3) offers a sustainable route for ammonia production, addressing agricultural needs and environmental concerns.
• Developing efficient and stable photocatalysts is crucial for advancing this technology, particularly for enhancing sunlight utilization and charge carrier dynamics.

Purpose of the Study:

• To design and synthesize novel polyoxometalates (POMs)-based zeolitic imidazolate framework-67 (ZIF-67) composite photocatalysts for enhanced N2 reduction.
• To investigate the effect of POMs integration and vanadium (V) substitution on the photocatalytic performance and stability of ZIF-67.

Main Methods:

• Fabrication of POMs-based ZIF-67 composites with varying V substitutions.
• Characterization of the synthesized materials using various analytical techniques.
• Evaluation of photocatalytic N2 reduction activity under simulated sunlight, quantifying ammonia yield and analyzing reaction mechanisms.

Main Results:

• The integration of POMs into ZIF-67 significantly improved sunlight absorption, suppressed electron-hole recombination, and enhanced charge transfer efficiency.
• The ZIF-67@K11[PMo4V8O40] composite exhibited the highest photocatalytic activity, achieving an ammonia yield of 149.0 μmol L⁻¹ h⁻¹, an 83.5% improvement over pristine ZIF-67.
• The V substitution in POMs positively correlated with photocatalytic performance, and the reduced POMs demonstrated a self-recoverable catalytic system.

Conclusions:

• POMs-based ZIF-67 composites are highly effective photocatalysts for N2 reduction, offering improved efficiency and stability.
• The developed self-recoverable photocatalytic system provides a promising pathway for sustainable ammonia synthesis.
• This research offers valuable insights into designing advanced nanomaterials for efficient N2 fixation.