Oxidative Polyoxometalates Modified Graphitic Carbon Nitride for Visible-Light CO₂ Reduction

Area of Science:

• Materials Science
• Photocatalysis
• Green Chemistry

Background:

• Developing efficient photocatalysts for carbon dioxide (CO2) reduction is crucial for mitigating global warming and reducing fossil fuel dependence.
• High-performance and low-cost photocatalytic materials are essential for practical CO2 photoreduction applications.

Purpose of the Study:

• To develop novel, inexpensive hybrid photocatalytic materials for CO2 reduction.
• To investigate the enhanced CO2 reduction activity and selectivity of a new composite material.

Main Methods:

• Synthesized noble-metal-free polyoxometalates (Co4) and integrated them with graphitic carbon nitride (g-C3N4) to form Co4@g-C3N4 hybrid materials.
• Utilized staggered band alignment in the composite for improved charge transfer.
• Evaluated photocatalytic CO2 reduction performance under visible light (λ ≥ 420 nm).

Main Results:

• The Co4@g-C3N4 hybrid materials exhibited significantly higher CO2 reduction activity compared to bare g-C3N4.
• An optimized sample achieved a high CO production yield of 107 μmol g⁻¹ h⁻¹ with 94% selectivity.
• Sustained CO production reached 896 μmol g⁻¹ after 10 hours of irradiation, indicating excellent stability.

Conclusions:

• The introduction of Co4 enhances charge transfer and surface catalytic oxidative ability in g-C3N4.
• This work presents a novel approach to designing low-cost, high-performance photocatalysts for CO2 reduction by combining g-C3N4 with oxidative polyoxometalates.