Tunable Covalent Triazine-Based Frameworks (CTF-0) for Visible-Light-Driven Hydrogen and Oxygen Generation from Water...

Area of Science:

• Materials Science
• Photocatalysis
• Green Chemistry

Background:

• Covalent triazine-based frameworks (CTFs) are semiconductive polymers with tunable band gaps and facile processing.
• CTFs show promise for photocatalytic water splitting, a key process for renewable energy.
• Optimizing CTF synthesis is crucial for enhancing their efficiency in water splitting.

Purpose of the Study:

• To investigate the effect of synthesis methods (microwave-assisted vs. ionothermal) on CTF-0 properties and photocatalytic water splitting performance.
• To compare the hydrogen and oxygen evolution activities of CTF-0 materials prepared by different methods.
• To understand how synthesis conditions modulate CTF band positions and structures for optimized photocatalysis.

Main Methods:

• Fabrication of CTF-0 materials using microwave-assisted synthesis and ionothermal methods.
• Photocatalytic water splitting experiments under visible light irradiation for hydrogen and oxygen evolution.
• Characterization of material properties including band gap, conduction band position, and charge separation efficiency.
• First-principles calculations to confirm structure-property relationships.

Main Results:

• Microwave-synthesized CTF-0-M2 exhibited significantly higher hydrogen evolution activity (7010 μmol h-1 g-1), 7 times greater than ionothermal CTF-0-I.
• Ionothermal CTF-0-I demonstrated superior oxygen evolution, producing ~6 times more oxygen than CTF-0-M2, with an AQY of 5.2% at 420 nm.
• CTF-0-M2 achieved a high turnover number (TON) of 726 for the platinum cocatalyst in hydrogen evolution over seven cycles.
• Synthesis conditions were found to modulate band positions and interlayer stacking, impacting optical and redox properties.

Conclusions:

• Microwave-assisted synthesis is highly effective for producing CTFs with enhanced hydrogen evolution capabilities.
• Ionothermal synthesis yields CTFs with superior oxygen evolution activity due to favorable band positions and active sites.
• Tailoring synthesis conditions offers a viable strategy to optimize CTFs for specific water splitting reactions (hydrogen or oxygen evolution).