Stopband tuning of TiO2 inverse opals for slow photon absorption

Abstract

The effect of photonic photocatalysis was explored employing TiO 2 inverse opal structures. The degradation of methylene blue in aqueous phase was performed under visible light (λ = 450 nm) irradiation and showed an improved degradation rate over TiO 2 inverse opals with respect to non-structured films. Moreover, tuning the stopband by means of varying the lattice parameter and the irradiation incident angle results in a further improvement of the photocatalytic rate due to the slow photon effect. The gas-phase photocatalytic degradation of acetaldehyde under UV irradiation and ISO-standard conditions showed a similar (0.6%) photonic efficiency in all the studied TiO 2 inverse opals regardless the photonic lattice parameter. Gas phase degradations were useful to investigate diffusional properties, in particular for small pore size samples. The mechanical stability of the samples, impacting directly on the structure-dependent photocatalytic performance, was also studied as a function of the consecutive photocatalytic reaction cycles.