Carbon nanosphere templates for the preparation of inverse opal titania photonic crystals by atomic layer deposition

Abstract Carbon nanospheres were used as templates for the first time to prepare titania inverse opal photonic crystal. From the spheres, opal colloid crystals were made by vertical deposition on microscope slides, and TiO2 was grown on them using atomic layer deposition (ALD). For this technique, the relatively high thermal stability and the presence of oxygen containing functional groups on the surface of the carbon spheres are beneficial. Subsequent annealing burned out the template spheres, leaving behind the inverse opal structures. The upper solid TiO2 layer was removed with argon ion sputtering. The samples were characterized with SEM, Raman spectroscopy, XRD, EDX, UV-Vis diffuse reflectance spectroscopy and their photocatalytic activity was investigated in decomposing organic dyes under UV and visible illumination. A new approach was used to test photocatalysis on the surface by utilizing UV-Vis reflectance and Raman spectroscopy in conjunction.