Defect-enhanced photothermal catalysis over ZnO for efficient depolymerization of waste polyester into high-purity...

Area of Science:

• Materials Science
• Catalysis
• Chemical Engineering

Background:

• Photothermal catalysis offers a sustainable route for chemical transformations.
• Zinc oxide (ZnO) is a promising semiconductor photocatalyst but requires performance optimization.
• Efficient conversion of waste polymers like polyethylene terephthalate (PET) is crucial for a circular economy.

Purpose of the Study:

• To enhance the photothermal catalytic performance of ZnO.
• To investigate the role of oxygen vacancies in improving ZnO's catalytic activity.
• To achieve efficient depolymerization of PET using a modified ZnO catalyst.

Main Methods:

• Synthesis of ZnO with controlled oxygen vacancies.
• Photothermal catalytic testing under simulated solar irradiation (2.2 W cm⁻²).
• Analysis of reaction products, including bis(2-hydroxyethyl) terephthalate (BHET), using techniques like HPLC.

Main Results:

• The engineered ZnO catalyst rapidly reached 190 °C under irradiation.
• Complete conversion of PET was achieved within 1 hour.
• High-purity bis(2-hydroxyethyl) terephthalate (BHET) was obtained with approximately 96% purity.
• The performance substantially outperformed pristine ZnO.

Conclusions:

• Oxygen vacancies are an effective strategy to significantly enhance the photothermal catalytic performance of ZnO.
• The developed ZnO catalyst demonstrates high efficiency and selectivity for PET conversion.
• This approach offers a promising pathway for the valorization of PET waste through photothermal catalysis.