Probing photonic effect on photocatalytic degradation of dyes based on 3D inverse opal ZnO photonic crystal

3D inverse opal ZnO photonic crystals (ZnO-PCs) with designed photonic bandgap (PBG) were prepared to study the pore size and slow photon effect on photocatalytic dye degradation. The PBGs of these ZnO-PC films were tuned experimentally by variation of the polystyrene sphere size of the opal templates. It was found that there is competition between the surface area and mass transport with increasing pore size during photocatalysis. ZnO-PCs exhibited higher photocatalytic activity under visible light irradiation, when the probe molecules were absorbed and well matched with the PBG. The enhancement could be attributed to intensified dye photosensitization as a result of the slow photon effect at the PBG edges, thus leading to a remarkable improvement in the light trapping. The present results provide useful information for developing high performance photocatalysts and photoanodes based on artificial photonic crystal design.