Temporal evolution of the absorption spectra of the aqueous RhB solution in the presence of hierarchically porous TiO2 nanomaterials (a) and commercial available TiO2 (b) under UV irradiation. Photocatalytic degradation over RhB of TiO2 (c). The squares represent hierarchically porous TiO2 nanomaterials whereas the triangles represent commercial TiO2. The solution was stirring in dark for the adsorption equilibrium in the initial 60 min.