Remarkably Enhancing H₂O₂ Photogeneration by Modulating Pore-Microenvironment of a Photoactive Covalent Organic...

Area of Science:

• Materials Science
• Photocatalysis
• Chemical Engineering

Background:

• Photocatalytic efficiency research often overlooks mass transfer limitations.
• Covalent organic frameworks (COFs) show promise for photocatalysis but require optimization.
• Improving reactant and product transport within photocatalysts is crucial for efficiency.

Purpose of the Study:

• To investigate the impact of enhanced mass transfer on photocatalytic hydrogen peroxide (H2O2) generation.
• To modulate the pore microenvironment of an imidazole-linked photoactive COF (PyNTB-COF) by grafting sulfonates.
• To evaluate the photocatalytic antimicrobial activity of the modified COF.

Main Methods:

• Grafting sulfonates onto PyNTB-COF to create sulfonated PyNTB-2SO3, enhancing pore microenvironment and mass transfer.
• Measuring H2O2 production rates using a sacrificial agent under photocatalysis.
• Assessing photocatalytic antimicrobial activity in outdoor water samples.

Main Results:

• Sulfonated PyNTB-2SO3 achieved an H2O2 production rate of 15158 µmol g⁻¹ h⁻¹, 20.6 times higher than the pristine COF.
• Enhanced mass transfer kinetics for reactants (·O2⁻, H2O, H⁺) and products were observed.
• Improved electron-hole separation and transfer capabilities due to sulfonic acid groups.
• Achieved >99% bacterial inactivation in 15 min, compared to ≈6 h for pristine COF.

Conclusions:

• Modulating the pore microenvironment to enhance mass transfer is a highly effective strategy for improving photocatalyst performance.
• Sulfonated COFs offer superior H2O2 generation and antimicrobial activity.
• This approach holds significant potential for developing practical, high-performance photocatalysts.