Probing photon localization effect between titania and photonic crystals on enhanced photocatalytic activity of titania film

•SiO2 opal instead of inverse opal was applied for its tunable structure parameters.•TiO2/SiO2 opal composite membrane shows improved photocatalytic activity.•The photocatalytic enhancement factor increased with the SiO2 opal periodicity.•The distance between TiO2 and SiO2 opal was tuned by thickness of SiO2 spacer.•The optimum periodicity and effective confining distance are obtained.