This work examined the photocatalytic destruction of sulfamethoxazole (SMX), a widely used antibiotic, under simulated solar radiation using iron-doped titanium dioxide as the photocatalyst. Amongst the various iron/titania ratios examined (in the range 0%–2%), the catalyst at 0.04% Fe/TiO₂ molar ratio exhibited the highest photocatalytic efficiency. The reaction rate followed pseudo-first-order kinetics, where the apparent kinetic constant was reduced as the initial concentration of SMX or humic acid increased. The photodecomposition of SMX was favored in natural pH but retarded at alkaline conditions. Unexpectedly, the presence of bicarbonates (in the range of 0.125–2 g/L) improved the removal of SMX, however, experiments conducted in real environmental matrices showed that process efficiency decreased as the complexity of the water matrix increased. The presence of sodium persulfate as an electron acceptor enhanced the reaction rate. However, only a small synergy was observed between the two individual processes. On the contrary, the addition of tert-butanol, a well-known hydroxyl radical scavenger, hindered the reaction, indicating the significant contribution of these radicals to the photocatalytic degradation of SMX. The photocatalyst retained half of its initial activity after five successive experiments.

Mn-, Co-, and Mn-Co doped TiO₂ ternary and quaternary semiconducting powder materials prepared by using the co-precipitation method and fully characterized by using x-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM — EDS) and UV- visible diffuse reflection spectroscopy were utilized for the photocatalytic degradation of methylene blue under visible light irradiation. These materials show a red shift and absorption in the visible region depending on the dopant type and concentration. These materials have proven to be effective as visible light photocatalysts.

Vanadium dioxide (VO₂) is a well-known thermochromic material that can potentially be used as a smart coating on glazing systems in order to regulate the internal temperature of buildings. Most growth techniques for VO₂ demand high temperatures (>250 °C), making it impossible to comply with flexible (polymeric) substrates. To overcome this problem, hydrothermally synthesized VO₂ particles may be dispersed in an appropriate matrix, leading to a thermochromic coating that can be applied on a substrate at a low temperature (<100 °C). In this work, we reported on the thermochromic properties of a VO₂/Poly-Vinyl-Pyrrolidone (PVP) nanocomposite. More specifically, a fixed amount of VO₂ particles was dispersed in different PVP quantities forming hybrids of various VO₂/PVP molar ratios which were deposited as films on fused silica glass substrates by utilizing the drop-casting method. The crystallite size was calculated and found to be 35 nm, almost independent of the PVP concentration. As far as the thermochromic characteristics are concerned, the molar ratio of the VO₂/PVP nanocomposite producing VO₂ films with the optimum thermochromic properties was 0.8. These films exhibited integral solar transmittance modulation (overall wavelengths) ΔTr_sol = 0.35%–1.7%, infrared (IR) switching at 2000 nm ΔTr_IR = 10%, visible transmittance at 550 nm Tr_Vis = 38%, critical transition temperature T_C = 66.8 °C, and width of transmittance hysteresis loop ΔT_C = 6.8 °C. Moreover, the critical transition temperature was observed to slightly shift depending on the VO₂/PVP molar ratio.