Modulation of the interfacial features of nanometric TiO2 by template-mediated synthesis

Interest in tuning the interfacial features of nanostructured TiO2 has been, recently, greatly increasing due to its enormous application potentials in different fields, from bio-materials to self-cleaning processes, from sensing to photovoltaic applications. In this study, the effect of synthetic parameters onto the interfacial properties of mesoporous TiO2 are investigated in detail, also concerning their effects on the resulting photocatalytic performances. Nano-TiO2 powders with controlled mesoporosity were synthesized by a modified EISA method using several block copolymers as structure directing agents. The obtained samples show a narrowly distributed mesoporosity that reflects the micellar dimensions. However, a partial pore collapse occurs during the crystallization of the oxide after the removal of the template. A tailored strategy for the removal of the template, involving a heat treatment followed by UV irradiation, was developed in order to maximize the sample porosity and surface area (determined by BET analysis). The resulting mesoporous oxides exhibit enhanced photocatalytic performances towards the mineralization of a well known dye, methylene blue. The granulometry of the powders (investigated by electronic microscopy and light scattering techniques), the particle electrification features and the stability of their suspensions are determined in order to shed light on the enhanced photocatalytic behaviour of these materials.