TiO₂-NGQD composite photocatalysts with switchable photocurrent response

Area of Science:

• Materials Science
• Nanotechnology
• Photocatalysis

Background:

• Titanium dioxide (TiO2) is a widely used photocatalyst, but its efficiency is limited by its wide bandgap.
• Graphene quantum dots (GQDs) offer unique electronic and optical properties that can enhance photocatalytic performance.
• Nitrogen doping can further tune the electronic structure of GQDs, improving their light absorption and charge separation capabilities.

Purpose of the Study:

• To synthesize and characterize novel TiO2-NGQD composite photocatalysts.
• To investigate the photocatalytic activity of these composites for phenol degradation under full spectrum and visible light.
• To explore the underlying mechanism, including photocurrent generation and charge carrier behavior.

Main Methods:

• Hydrothermal synthesis of TiO2-NGQD composites with varying NGQD content.
• Photocatalytic degradation experiments using phenol as a model pollutant.
• Characterization of photocurrent generation under different light sources (full spectrum vs. visible).
• Monitoring of phenol degradation using nuclear magnetic resonance (NMR) spectroscopy.

Main Results:

• All synthesized TiO2-NGQD composites exhibited superior photocatalytic activity compared to commercial P25 TiO2.
• The 8 wt% NGQD composite demonstrated a significant enhancement of over 600% in visible light photocatalysis.
• The composites showed tunable photocurrent behavior (anodic to cathodic) depending on the light source.
• A Z-scheme heterojunction mechanism was proposed to explain the enhanced performance.

Conclusions:

• TiO2-NGQD composites are highly effective photocatalysts for phenol degradation.
• The tunable charge carrier generation in TiO2-NGQDs opens avenues for advanced applications.
• These materials hold significant promise for applications in photocatalysis, energy harvesting, and water splitting.