Highly Efficient Visible-Light-Induced Photocatalytic Activity of Fe-Doped TiO2 Nanoparticles

Bare TiO2 and nominal 5.0 at% Fe-doped TiO2 nanoparticles were synthesized by the modified sol-gel method. The samples were physically characterized in order to obtain the correlation between structure and photocatalytic properties by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer, Emmett and Teller (BET), and UV-vis diffuse reflectance spectrophotometry (UV-vis DRS). XRD results indicated that phase structures of bare TiO2 and Fe-doped TiO2 nanoparticles were the mixture of anatase and rutile phases. The content of rutile phase in 5.0 at% Fe-doped TiO2 nanoparticles decreased . TEM images revealed that the shape of bare and 5.0 at% Fe-doped TiO2 was almost spherical and the average particle size was in the range of 10-30 nm. Specific surface areas of the samples were found as 75 and 134 m2/g for bare TiO2 and nominal 5.0 at% Fe-doped TiO2, respectively. The results from UV-vis reflectance spectra clearly indicated the shift of absorption band edge towards visible region upon doping TiO2 with iron. Photocatalytic activity of bare TiO2 and 5.0 at% Fe-doped TiO2 nanoparticles was examined by studying the mineralization of oxalic acid under visible light irradiation and the results clearly showed that Fe-doped TiO2 sample exhibited higher activity than bare TiO2

Synthesis and Characterization of the Novel BiVO4/CeO2 Nanocomposites

Novel BiVO4/CeO2 nanocomposites were synthesized by the hydrothermal method combined with the homogeneous precipitation method. The mole ratios of BiVO4:CeO2 were 0.4:0.6, 0.5:0.5, and 0.6:0.4. The obtained BiVO4/CeO2 nanocomposites were characterized by X-ray diffraction (XRD) for phase composition and crystallinity. Particle sizes, morphology and elemental composition of BiVO4/CeO2 composites were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). The Brunauer, Emmett and Teller (BET) adsorption-desorption of nitrogen gas for specific surface area determination at the temperature of liquid nitrogen was performed on all samples. UV-vis diffuse reflectance spectra (UV-vis DRS) were used to identify the absorption range and band gap energy of the composite catalysts. The results indicated that BiVO4/CeO2 samples retained monoclinic scheelite and fluorite structures. The morphologies of nanocomposite samples consisted of rod-like, plate-like and spheroidal shapes. Specific surface area (SSABET) of the novel synthesized catalysts drastically increased from 38 - 150 m2/g whereas an average BET-equivalent particle diameter (dBET) significantly decreased from 30 - 12 nm, upon increasing the amount of CeO2 in the BiVO4/CeO2 composite. The absorption spectra of all nanocomposite samples were shifted to the visible region, suggesting the potential application of this novel composite as an active visible-light driven photocatalyst

Photocatalytic Degradation of Phenol Using Nb-Loaded ZnO Nanoparticles

Niobium-doped Zinc Oxide nanoparticles (Nb-doped ZnO NPs) in the range of 20 and 40 nm were synthesized by Flame Spray Pyrolysis (FSP) technique. The crystalline phase, morphology and size of the nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-vis spectroscopy. The specific surface area of the nanoparticles was measured by nitrogen adsorption (BET analysis). The pure ZnO and Nb-doped ZnO NPs were found to have the clear spherical, hexagonal and rod-like morphologies. To the best of our knowledge, the application of Nb-doped ZnO NPs as a photocatalyst has not been reported yet. In this study, the photocatalytic activities of pure ZnO and Nb-doped ZnO NPs were determined by studying the mineralization of phenol under UV light illumination. The results indicated that all Nb-doped ZnO NPs have better photocatalytic activity than the pure ZnO nanoparticles. It was found that, 0.50 mol% Nb-doped ZnO NPs exhibited the fastest response to the degradation of phenol

Photocatalytic Mineralization of Organic Acids over Visible-Light-Driven Au/BiVO 4

Au/BiVO4 visible-light-driven photocatalysts were synthesized by coprecipitation method in the presence of sodium dodecyl benzene sulfonate (SDBS) as a dispersant. Physical characterization of the obtained materials was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), UV-Vis diffuse reflectance spectroscopy (DRS) and Brunauer, and Emmett and Teller (BET) specific surface area measurement. Photocatalytic performances of the as-prepared Au/BiVO4 have also been evaluated via mineralizations of oxalic acid and malonic acid under visible light irradiation. XRD and SEM results indicated that Au/BiVO4 photocatalysts were of almost spherical particles with scheelite-monoclinic phase. Photocatalytic results showed that all Au/BiVO4 samples exhibited higher oxalic acid mineralization rate than that of pure BiVO4, probably due to a decrease of BiVO4 band gap energy and the presence of surface plasmon absorption upon loading BiVO4 with Au as evidenced from UV-Vis DRS results. The nominal Au loading amount of 0.25 mol% provided the highest pseudo-first-order rate constant of 0.0487 min−1 and 0.0082 min−1 for degradations of oxalic acid (C2) and malonic acid (C3), respectively. By considering structures of the two acids, lower pseudo-first-order rate constantly obtained in the case of malonic acid degradation was likely due to an increased complexity of the degradation mechanism of the longer chain acid

Evaluation of Coating Ability of TiO2 Nanoparticles onto Aluminum Alloy Sheet by Physicochemical Analysis

TiO2 nanoparticle films were successively coated onto aluminum (Al) alloy sheet using a coating technique at 150C for 5 h. This was a chemical sintering method, integrated with Al/TiO2/Al sandwich coupling and used weak acid as a binder. To evaluate the coating ability of the TiO2 nanoparticles on the aluminum alloy sheet, the physicochemical characteristics of the film samples were analyzed by means of SEM-EDS, FT-IR and XRD. The TiO2 films prepared by the coating technique at 150C for 5 h were compared with TiO2 films prepared by the doctor-blade technique at 500C for 10 min using two different organics as binders. The results of the physicochemical analysis indicated that the coating technique at 150C for 5 h provided superior coating ability of TiO2 nanoparticles onto aluminum alloy sheet than the doctor-blade technique. This may have been because of reduction of the thermal gradient at the TiO2 interface, which affected the relaxation of internal and external stresses on the TiO2 film on the aluminum alloy substrate. In this work, the TiO2 film prepared by chemical sintering method, integrated with Al/TiO2/Al sandwich coupling at 150C for 5 h using weak acid mixed with 5 wt.% ammonia as a binder proved to produce the optimum TiO2 film; however, film thickness control using the coating technique at 150C for 5 h still needs to be developed.</jats:p

Influence of Cu doping on the visible-light-induced photocatalytic activity of InVO₄

The photocatalytic degradation of methylene blue (MB) in the presence of pure InVO4 and 0.5–5.0 mol% Cu-doped InVO4 samples under visible light irradiation (λ ≥ 400 nm) was studied in this research.</p