TiO2 nanoparticles were synthesized from titanium isopropoxide by a simple peptization method using sulfuric, nitric, and acetic acids. The effect of peptizing acid on physicochemical and photocatalytic properties of TiO2 powders was studied. The structural properties of synthesized TiO2 powders were analyzed by using XRD, TEM, N2-physisorption, Raman, DR UV-vis, FTIR, and X-ray photoelectron spectroscopy techniques. The characterization results showed that acetic acid peptization facilitated the formation of pure anatase phase after thermal treatment at 500 °C; in contrast, nitric acid peptization led to a major rutile phase formation (67%). Interestingly, the sample peptized using sulfuric acid yielded 95% anatase and 5% rutile phases. The photocatalytic activity of synthesized TiO2 nanoparticles was evaluated for degradation of selected organic dyes (crystal violet, methylene blue, and p-nitrophenol) in aqueous solution. The results confirmed that the TiO2 sample peptized using nitric acid (with rutile and anatase phases in 3:1 ratio) offered the highest activity for degradation of organic dyes, although, TiO2 samples peptized using sulfuric acid and acetic acid possessed smaller particle size, higher band gap energy, and high surface area. Interestingly, TiO2 sample peptized with nitric acid possessed relatively high theoretical photocurrent density (0.545 mAcm−2) and pore diameter (150 Å), which are responsible for high electron-hole separation efficiency and diffusion and mass transportation of organic reactants during the photochemical degradation process. The superior activity of TiO2 sample peptized with nitric acid is due to the effective transfer of photogenerated electrons between rutile and anatase phases.

Mesoporous CuO-ZrO₂ catalysts were prepared and calcined at 500 °C. The performance of the synthesized catalysts for benzylation of benzene using benzyl chloride was studied. The bare support (macroporous ZrO₂) offered 45% benzyl chloride conversion after reaction time of 10 h at 75 °C. Significant increase in benzyl chloride conversion (98%) was observed after CuO loading (10 wt. %) on porous ZrO₂ support. The conversion was decreased to 80% with increase of CuO loading to 20 wt. %. Different characterization techniques (XRD, Raman, diffuse reflectance UV-vis, N₂-physisorption, H₂-TPR, XPS and acidity measurements) were used to evaluate physico-chemical properties of CuO-ZrO₂ catalysts; the results showed that the surface and structural characteristics of the ZrO₂ phase as well as the interaction between CuO-ZrO₂ species depend strongly on the CuO content. The results also indicated that ZrO₂ support was comprised of monoclinic and tetragonal phases with macropores. An increase of the volume of monoclinic ZrO₂ phase was observed after impregnation of 10 wt. % of CuO; however, stabilization of tetragonal ZrO₂ phase was noticed after loading of 20 wt. % CuO. The presence of low-angle XRD peaks indicates that mesoscopic order is preserved in the calcined CuO-ZrO₂ catalysts. XRD reflections due to CuO phase were not observed in case of 10 wt. % CuO supported ZrO₂ sample; in contrast, the presence of crystalline CuO phase was observed in 20 wt. % CuO supported ZrO₂ sample. The mesoporous 10 wt. % CuO supported ZrO₂ catalyst showed stable catalytic activity for several reaction cycles. The observed high catalytic activity of this catalyst could be attributed to the presence of a higher number of dispersed interactive CuO (Cu²⁺-O-Zr⁴⁺) species, easy reducibility, and greater degree of accessible surface Lewis acid sites.

Novel photocatalytic metal–organic framework (MOF) materials are an exciting research topic. However, the lack of investigating rare-earth doped semiconductor as well as understanding their physicochemical and structural characterization will prevent commercial or industrial applications. To overcome this obstacle, this study investigates the physicochemical and structural characterization of novel applied Titania-based materials synthesized via MOF strategy for photodegradation of methyl orange (MO). The studied materials are TiO₂, Pr-doped TiO₂ (Pr@TiO₂), and Nd-TiO₂ (Nd@TiO₂) and applied as promising photocatalysts. The synthesized photocatalysts were prepared via metal–organic framework strategy and characterized by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS). SEM analysis revealed that only Nd resulted in smaller, more uniform particle sizes. XRD patterns confirmed the retention of the anatase phase in the case of Nd-modification, indicating successful lattice distortions. XPS results showed the chemical existence of Pr and Nd, increased oxygen vacancies, and surface hydroxyl groups, essential for enhanced photocatalytic activity. Photodegradation studies demonstrated that both Pr-TiO₂ and Nd-TiO₂ exhibited better performance compared to TiO₂ without Pr or Nd, following pseudo-first-order kinetics. These findings highlight the potential of Pr and Nd modification in the TiO₂ photocatalysts for efficient environmental remediation, particularly in the treatment of dye-containing wastewater.