The effect of photonic band gap on the photo-catalytic activity of nc-TiO2/SnO2 photonic crystal composite membranes

• nc-TiO2/SnO2 photonic crystal composite membranes were fabricated.
• The photocatalytic activity of the composite membranes was greatly enhanced.
• The nc-TiO2 harvests slow photons produced by the SnO2 photonic crystal layer.
• The closer the PBG to the EBG of TiO2, the greater the catalytic activity.

nc-TiO2/SnO2 photonic crystal composite membranes were prepared by depositing nanocrystalline TiO2 layers on top of inverse opal SnO2 photonic crystals films. The photonic band gap of the SnO2 photonic crystals layer was tuned by changing the particles size of polystyrene microspheres. Photons trapped in the SnO2 photonic crystal layer are more effectively absorbed by TiO2 at the TiO2/SnO2 interface creating photoelectrons that assist in oxidation reactions. It was shown that the closer the photonic band gap of the phonic crystals layers matches the electronic band gap of TiO2 catalyst layer, the higher the photocatalytic activity of the composite membranes. The photo-activity of TiO2 can be enhanced by the synergistic effect of photonic crystal light localization at the SnO2/TiO2 interface.

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