Yttrium deposition on mesoporous TiO2: textural design and UV decolourization of organic dyes

This study discusses about the photochemical, topological and textural properties of yttrium-doped titanium dioxide (TiO2) photocatalysts. The mesoporous yttrium-doped TiO2 substrates prepared in this research work operate efficiently via low-cost commercial 13-W UV lamps. A quantity of 2 wt% yttrium deposition on TiO2 accelerates methyl orange UV decolourization kinetics. When Y content increases to 8 wt%, besides anatase, rutile is formed from 600°C. The Y2Ti2O7 photoinactive compound emerges at 800°C. The P-123 surfactant mesopore templating treatment of TiO2 xerogels (when concurrent with the sol–gel Y-doping of Ti alkoxides) features the following two correlated phenomena: (i) The surface area increases while the access to the inner porosity of the substrate becomes much easier, so that a larger portion of the surface is made accessible to the dye molecules as well as to the yttrium dopant; (ii) the inclusion of tubular instead of ink-bottle pores facilitates the transport of organic species in and out of the pore structure. The most active mesoporous substrate resulted to be made of 2 wt% Y; contrastingly, when Y=8 wt%, photoinactivity arose because of Y2Ti2O7 formation. The involvement of P123 was not the sole factor influencing the efficiency of TiO2 mesoporous photocatalysts. There were additional key factors, such as the surging of co-ordination and nucleophilic species, during the dye photodegradation process, which were also induced by the presence of Y species on the surface of these substrates.