Iron promotion of the TiO2 photosensitization process towards the photocatalytic oxidation of azo dyes under solar-simulated light irradiation

Performance of Ag-TiO2Photocatalysts towards the Photocatalytic Disinfection of Water under Interior-Lighting and Solar-Simulated Light Irradiations

“…Probably, the increase in N residues coming from the Ag salt precursor, AgNO 3 , may lead to new intrabandgap states promoting electronic transitions of lower energy requirements between N and the TiO 2 conduction band, thus leading to a decrease in the energy gap [36]. However, as we have stated, in a previous work, NO 3 − residues in Fe-TiO 2 samples, obtained by the hydrothermal route, do not promote photoactivity under vis light [4]. Therefore, DRS spectra observed in Figure 1 suggest that increased absorption due to Ag presence, with a peak at ∼460 nm, is possibly due to the localized surface plasmon resonance of Ag nanoparticles [37,38].…”

“…Moreover, Ti 3+ is expected to be rapidly oxidized to Ti 4+ by surrounding oxygen [48]. However, in this case the chosen synthesis route leads to formation of anatase-brookite mixed phase oxide with ∼50% of amorphous, as early discussed, including organic residues as we have observed in a previous work [4]. Such residues may protect surface oxidation of Ti 3+ to Ti 4+ thus allowing its detection in XPS analyses.…”

“…A slight decrease in crystallite size was observed due to Ag loading probably due to obstruction to anatase crystallite growth by Ag aggregates located in crystal borders. Fe 3+ modifications on TiO 2 , using the same hydrothermal synthesis, promoted changes on the crystalline structure due to its similarity in sizes with Ti 4+ ions, thus replacing Ti atoms and decreasing crystallite size [4]. Therefore, it is possible to suggest that during the synthesis Ag aggregates are deposited on the surface or grain boundaries.…”

“…TiO 2 , as a semiconductor, is activated under UV irradiation promoting charges that lead to the formation of reactive oxygen species when they interact with H 2 O and O 2 from the reaction media. Nowadays, recombination of the photogenerated charges [4,5] and visible (vis) light response [4] are two drawbacks still to surpass in order to achieve efficient photocatalysts to be used under solar light or interiorlighting irradiations.…”

A mini-review on rare earth metal-doped TiO2 for photocatalytic remediation of wastewater

“…In order to reduce the electron-hole recombination and to shift the absorption wavelength to the desired visible region (>λ = 400 nm), various selective surface modifications have been conducted including metal and non-metal doping (Chen and Mao 2007;Castro et al 2011;Ramacharyulu et al 2014;Vasilić et al 2015), dye sensitization (Chowdhury et al 2012;Daghrir et al 2013) and coupling to increase the efficiency of the photocatalyst (Daghrir et al 2013). Generally, the applications of titania are divided into two categories (i) energy and (ii) environmental (Chen and Mao 2007).…”