Photocatalytic behavior of colored mortars containing TiO<inf>2</inf> and iron oxide based pigments: Fid-Bau Portal

Photocatalytic behavior of colored mortars containing TiO2 and iron oxide based pigments

Laplaza, A. / Jimenez-Relinque, E. / Campos, J. / Castellote, M.

Highlights•Photocatalytic activity of iron based pigment-TiO2 mortar depends on electron transfer.•Electron transfer depends on the band positions of pigment-TiO2 heteroestructure.•Electron transfer depends on ratio iron-TiO2 of pigment-cement heteroestructure.•Electron transfer of iron based pigment-TiO2 mortar inhibited the recombination.•There is an optimum iron-TiO2 ratio that minimizes the electron transfer ability.

AbstractThis paper analyses the effect of adding iron based pigments to produce photocatalytic colored mortars (Ph-CM) evaluating nitrogen oxide air purification-NOx, Rhodamine B self-cleaning-RhB and formation rate of hydroxyl radicals-OH. All Ph-CM tested shifted towards lower energy values with respect to the absorption-edge of the TiO2-mortar samples without pigments. However, different UV–Visible photoactivity behavior was obtained in function of the type and content of pigment. The results indicate that even though a decrease in the photocatalytic efficiency can occur, in some cases, an interfacial electron transfer between the conduction band of iron pigment and the photocatalytic mortar could also take place, resulting in an effective inhibition of electron-hole recombination, higher formation rate of OH, and thereby higher photocatalytic activity. This electron transfer ability directly depends on the band-edge position of pigment-cement heteroestructure and the iron to pigment ratio.