Solar-matched S-scheme ZnO/g-C₃N₄ for visible light-driven paracetamol degradation

Area of Science:

• Environmental Science
• Materials Science
• Catalysis

Background:

• Pharmaceuticals like paracetamol are persistent pollutants in wastewater.
• Visible light-driven photocatalysis offers a sustainable degradation method.
• Zinc oxide (ZnO) and graphitic carbon nitride (g-C3N4) are promising photocatalytic materials.

Purpose of the Study:

• To fabricate and optimize ZnO/g-C3N4 S-scheme heterojunction photocatalysts.
• To evaluate their efficiency in degrading paracetamol under visible light.
• To understand the mechanism behind the enhanced photocatalytic activity.

Main Methods:

• Synthesis of ZnO/g-C3N4 composites with varying g-C3N4 content (wt.%).
• Characterization of photocatalyst properties, including band gap and surface area.
• Visible light-driven photocatalytic degradation experiments for paracetamol.
• Trapping experiments to identify reactive oxygen species.

Main Results:

• The optimized 10 wt.% g-C3N4/ZnO composite exhibited 95% paracetamol degradation in 60 minutes under visible light.
• This represents a 2.24-fold increase in reaction rate compared to lower composites and pristine g-C3N4.
• Band gap narrowing, efficient charge transfer via S-scheme heterojunction, and abundant active sites contributed to high activity.
• Hydroxyl radicals were identified as the primary reactive species.

Conclusions:

• The ZnO/g-C3N4 S-scheme photocatalyst is highly effective for visible light-driven paracetamol degradation.
• The optimized composite demonstrates excellent photostability and reusability.
• This research presents a significant advancement in developing sustainable catalysts for pharmaceutical pollutant removal.