Improving Visible Light Photocatalysis Using Optical Defects in CoO_x-TiO₂ Photonic Crystals

Area of Science:

• Materials Science
• Photocatalysis
• Nanotechnology

Background:

• Photonic crystal photocatalysts offer enhanced light harvesting and performance.
• Rational design is crucial for optimizing light propagation and catalytic activity.
• CoOₓ-TiO₂ inverse opals are promising for visible light photocatalysis.

Purpose of the Study:

• To enhance slow light propagation and visible light photocatalysis.
• To demonstrate the effect of integrating a planar defect into CoOₓ-TiO₂ inverse opals.
• To improve light localization and photocatalytic efficiency.

Main Methods:

• Fabrication of trilayer photonic crystal films (inverse opal TiO₂, titania interlayer, photonic top layer).
• Surface modification with CoOₓ nanoscale complexes for visible light activation.
• Optical and electrochemical impedance measurements to analyze light propagation and charge transfer.

Main Results:

• Formation of "donor"-like localized states within the photonic band gap.
• Reduced Bragg reflection and expanded slow photon spectral range.
• Markedly improved photocatalytic performance for salicylic acid degradation and photocurrent generation.
• Reduced recombination kinetics observed through electrochemical impedance.

Conclusions:

• Integrating an optical defect into inverse opal photocatalysts is a versatile strategy.
• This approach effectively boosts photonic amplification effects in visible light photocatalysis.
• The method overcomes limitations of narrow slow photon spectral regions, enhancing photocatalytic efficiency.