Li–Y doped and codoped TiO2 thin films: Enhancement of photocatalytic activity under visible light irradiation

Sol−gel synthesis based on the self-assembling template method has been applied to synthesize Li–Y doped and co-doped TiO₂ not only to improve simultaneously the structural and electronic properties of TiO₂ nanomaterials but also to achieve Li–Y doping of titania with high photocatalytic reactivity. The characterization of the samples was performed by GXRD, GSDR, FT-IR, and Raman spectroscopy. According to the GXRD patterns, all the observed reflections can be indexed using the anatase form of TiO₂, Which is confirmed by ground state diffuse reflectance and micro-Raman spectra. The Li–Y doped titania materials immobilized as nanostructured thin films on glass substrates exhibit high photocatalytic efficiency for the degradation of toluidine and benzoic acid under visible light irradiation. The development of these visible light-activated nanocatalysts has the potential of providing environmentally benign routes for water treatment.     

Preparation and characterization of a novel activated carbon‐supported N‐doped visible light response photocatalyst (TiO2−xNy/AC)

A photocatalyst, TiO_2?xN_y/AC (activated carbon (AC) supported N‐doped TiO₂), highly active in both the Vis and UV range, was prepared by calcination of the TiO₂ precursor prepared by acid‐catalyzed hydrolysis in an ammonia atmosphere. The powders were characterized by diffuse reflectance spectroscopy, scanning electron microscopy, X‐ray diffraction, N₂ adsorption, Fourier transform infrared spectroscopy and phenol degradation. The doped N in the TiO₂ crystal lattice creates an electron‐occupied intra‐band gap allowing electron‐hole pair generation under Vis irradiation (500–560 nm). The TiO_2?xN_y/AC exhibited high levels of activity and the same activity trends for phenol degradation under both Vis and UV irradiation: TiO_2?xN_y/AC calcined at 500 °C for 4 h exhibited the highest activity. The band‐gap level newly formed by doped N can act as a center for the photo‐generated holes and is beneficial for the UV activity enhancement. The performance of the prepared TiO_2?xN_y/AC photocatalyst revealed its practical potential in the field of solar photocatalytic degradation of aqueous contaminants. Copyright © 2007 Society of Chemical Industry     

Carbonaceous-TiO2 nanomaterials for photocatalytic degradation of pollutants: A review

Semiconductor photocatalysis is one of most appealing and attractive technologies, which has been directly utilized to harvest solar energy for energy and environmental applications. Titanium dioxide (TiO₂) has been proved to be leading semiconductor photocatalyst for the degradation of pollutants. However, it suffers from low photocatalytic activity under visible light activation because of its intrinsic wide band gap. Various strategies have been developed to enhance TiO₂ efficiency in the visible light region. Among them TiO₂ modification with carbonaceous nanomaterials is very effective route for excellent photocatalytic activity. This critical review aims to present recent progress in the design and synthesis of carbonaceous-TiO₂ photocatalysts, covering carbon doping, activated carbon, fullerenes, carbon nanotubes and graphene. Moreover, proposed mechanisms of enhancement, effect of synthesis routes, demonstrations of performance and applications reported in literature are reviewed. Ongoing challenges and possible new directions are outlined.     

Visible light induced self-cleaning performance of iron-doped TiO2 nanoparticles for surface applications

This study aimed to enhance the visible light photosensitivity of TiO₂ nanoparticles for self-cleaning applications by doping with Fe³⁺. Nanocrystalline undoped and Fe-doped TiO₂ (Ti_1 − xFe_xO₂, x = .01–.04) were synthesized via sol–gel method. The results demonstrated that Fe-doped TiO₂ nanoparticles exhibited visible light sensitivity and self-cleaning properties. An increased Fe concentration resulted in a red shift in the absorption band edge. Fe_0.03-doped TiO₂ with an average particle size of ∼21 nm, a crystallite size of ∼12 nm, and a band gap of ∼2.86 eV showed the highest photocatalytic activity (60% methylene blue degradation) and super-hydrophilicity (water droplet contact angle 9°) under visible light radiation. These findings highlight the potential of Fe-doped TiO₂ nanoparticles as a promising material for self-cleaning applications.     

Synthesis and visible‐light‐derived photocatalysis of titania nanosphere stacking layers prepared by chemical vapor deposition

BACKGROUND: In this study, visible‐light‐derived photocatalytic activity of metal‐doped titanium dioxide nanosphere (TS) stacking layers, prepared by chemical vapor deposition (CVD), was investigated. The as‐grown TS spheres, having an average diameter of 100–300 nm, formed a layer‐by‐layer stacking layer on a glass substrate. The crystalline structures of the TS samples were of anatase‐type. RESULTS: Ultraviolet (UV) absorption confirmed that metallic doping (i.e. Co and Ni) shifted the light absorption of the spheres to the visible‐light region. With increasing dopant density, the optical band gap of the nanospheres became narrower, e.g. the smallest band gap of Co‐doped TS was 2.61 eV. Both Ni‐ and Co‐doped TS catalysts showed a photocatalytic capability in decomposing organic dyes under visible irradiation. In comparison, Co‐doped TiO₂ catalyst not only displays the adsorption capacity, but also the photocatalytic activity higher than the N‐doped TiO₂ catalyst. CONCLUSION: This result can be attributed to the fact that the narrower band gap easily generates electron–hole pairs over the TS catalysts under visible irradiation, thus, leading to the higher photocatalytic activity. Accordingly, this study shed some light on the one‐step efficient CVD approach to synthesize metal‐doped TS catalysts for decomposing dye compounds in aqueous solution. Copyright © 2010 Society of Chemical Industry     

Microwave photocatalysis III. Transition metal ion‐doped TiO2 thin films on mercury electrodeless discharge lamps: preparation,characterization and their effect on the photocatalytic degradation of mono‐chloroacetic acid and Rhodamine B

BACKGROUND: Mercury electrodeless discharge lamps (Hg‐EDLs) were used to generate UV radiation when exposed to a microwave field. EDLs were coated with doped TiO₂ in the form of thin films containing transition metal ions Mⁿ⁺ (M = Fe, Co, Ni, V, Cr, Mn, Zr, Ag). Photocatalytic degradation of mono‐chloroacetic acid (MCAA) to HCl, CO₂, and H₂O, and decomposition of Rhodamine B on the thin films were investigated in detail. RESULTS: Polycrystalline thin doped TiO₂ films were prepared by dip‐coating of EDL via a sol–gel method using titanium n‐butoxide, acetylacetone, and a transition metal acetylacetonate. The films were characterized by Raman spectroscopy, UV/Vis absorption spectroscopy, X‐ray photoelectron spectroscopy (XPS), electron microprobe analysis and by atomic force microscopy (AFM). The photocatalytic activity of doped TiO₂ films was monitored in the decomposition of Rhodamine B in water. Compared with the pure TiO₂ film, the UV/Vis spectra of V, Zr and Ag‐doped TiO₂ showed significant absorption in the visible region, and hence the photocatalytic degradation of MCAA had increased. The best apparent degradation rate constant (0.0125 min^?1), which was higher than that on the pure TiO₂ film by a factor of 1.7, was obtained with the Ag(3%)/TiO₂ photocatalyst. The effect of doping level of vanadium acetylacetonate on the photocatalytic efficiency of the V‐doped TiO₂ was determined. CONCLUSIONS: Transition metal ion‐doped TiO₂ thin films showed significant absorption in the visible region. The metal doped TiO₂ photocatalyst (with an appropriate amount of V, Zr and Ag) on the Hg‐EDLs increased the degradation efficiency of MCAA in a microwave field. Copyright © 2009 Society of Chemical Industry     

Band‐Gap Engineering and Enhanced Photocatalytic Activity of Sm and Mn Doped BiFeO3 Nanoparticles

Bi_1‐xSm_xFe_1‐yMn_yO₃ (BSFMO, x = 0.0, 0.05; y = 0.0, 0.05, 0.10, 0.15, 0.20, 0.25) nanoparticles were synthesized by using double solvent sol–gel method. Photocatalytic activity was investigated under UV and visible‐light illumination. The structural, morphological, and optical properties were analyzed by X‐ray diffraction, scanning electron microscopy, and UV‐vis spectroscopy respectively. The crystallite size of BiFeO₃ (BFO) decreases from (57.3–17.2 nm) with the increase in Sm and Mn‐doping concentration. The surface morphology shows that the pure and Sm‐doped BFO nanoparticles are irregular in shape but changes to spherical shape after Mn‐doping up to 25%. The band‐gap engineering of BFO nanoparticles is achieved by co‐doping of Sm and Mn. The band‐gap of BFO could be tuned successfully from 2.08–1.45 eV, which may be due to the distortion induced in Fe‐O octahedron and the rearrangement of molecular orbitals. These results give rise to enhanced photocatalytic activity by degradation of organic dyes (MB, CR, and MV) under the visible‐light illumination.     

The Synthesis and Photocatalytic Properties of Nitrogen Doped TiO<Subscript>2</Subscript> Films Prepared Using the AC-PLD Method

Synthesis of N doped TiO₂ films were conducted by the atmospheric controlled pulsed laser deposition (AC-PLD) method to generate visible light active photocatalytic films. In this method, the anion doped TiO₂ films were synthesized on a quartz substrate by the irradiation of a pulsed Nd:YAG laser on a TiO₂ target in the presence of gaseous nitrogen containing reagents at reduced pressure. For nitrogen doping, the use of CH₃CN was found to be more effective than the use of NH₃. The visible light absorption properties of the films were very sensitive to the CH₃CN partial pressure during ablation. When using CH₃CN, nitrogen and an equal quantity of carbon was uniformly doped into the TiO₂ films. The resultant films showed better catalytic performance than those which were either un-doped or doped using NH₃. The formation of nitrogen doped TiO₂ is discussed by relating experimental results to thermodynamic considerations. It is also suggested that stronger reducing agents such as carbon are required for doping nitrogen into TiO₂ films.     

Fabrication of core–shell nanocomposites with enhanced photocatalytic efficacy

The current study establishes the unprecedented involvement in the evolution and production of novel core–shell nanocomposites composed of nanosized titanium dioxide and aniline‐o‐phenylenediamine copolymer. TiO₂@copoly(aniline and o‐phenylenediamine) (TiO₂@PANI‐o‐PDA) core–shell nanocomposites were chemically synthesized in a molar ratio of 5:1 of the particular monomers and several weights of nano‐TiO₂ via oxidative copolymerization. The construction of the TiO₂@PANI‐o‐PDA core–shell nanocomposites was ascertained from Fourier transform IR spectroscopy, UV–visible spectroscopy and XRD. A reasonable thermal behavior for the original copolymer and the TiO₂@PANI‐o‐PDA core–shell nanocomposites was investigated. The bare PANI‐o‐PDA copolymer was thermally less stable than the TiO₂@PANI‐o‐PDA nanocomposites. The core–shell feature of the nanocomposites was found to have core and shell sizes of 17 nm and 19–26 nm, respectively. In addition, it was found that the addition of a high ratio of TiO₂ nanoparticles increases the electrical conductivity and consequently lowers the electrical resistivity of the TiO₂@PANI‐o‐PDA core–shell nanocomposites. The hybrid photocatalysts exhibit a dramatic photocatalytic efficacy of methylene blue degradation under solar light irradiation. A plausible interpretation of the photocatalytic degradation results of methylene blue is also demonstrated. Our setup introduces a facile, inexpensive, unique and efficient technique for developing new core–shell nanomaterials with various required functionalities and colloidal stabilities. © 2018 Society of Chemical Industry     

Enhanced visible‐light‐driven photocatalytic activities of LiInO2 by Mo6+‐doping strategy

A novel visible‐light‐driven photocatalyst of Mo‐doped LiInO₂ nanocomposite was successfully synthesized through a sol‐gel method. The effect of Mo‐doping concentrations on the microstructures and properties of LiInO₂ was characterized by X‐ray diffraction, scanning electron microscope, X‐ray photoelectron spectroscopy, photoluminescence, and ultraviolet‐visible absorption spectra. The photocatalytic properties of the as‐prepared samples were evaluated by the photocatalytic degradation of methylene blue (MB) dye under visible‐light irradiation. The results demonstrated that the photocatalytic activity of 6% Mo‐LiInO₂ reached to 98.6%, which was much higher than that of the undoped photocatalyst LiInO₂ (only 46.8%). The enhanced photocatalytic activity is ascribed to Mo‐doping strategy. The holes play an important role in the process of the photodegradation of MB. The superior photocatalytic activity of the as‐prepared Mo‐LiInO₂ nanocomposites suggests a potential application for organic dye degradation of wastewater remediation. This work provides a further understanding on tailoring the band structure of semiconductor photocatalyst for enhancing visible‐light absorption and promoting electron‐hole separation by Mo‐doping strategy.     

Nanostructured Solids from Freeze‐Dried Precursors: Multigram Scale Synthesis of TiO2‐Based Powders

Nanocrystalline TiO₂ and Ti_1?xV_xO₂ (x = 0.01) powders have been prepared by thermal decomposition, in air, of amorphous precursors resulting from the freeze‐drying of appropriate solutions. In addition, TiO_2?xN_y (anatase and rutile) and TiO_xN_y (rock‐salt) have been prepared by thermal treatment in ammonia of a crystalline precursor (TiO₂ obtained at 673 K). TEM and SEM images, as well as the analysis of the X‐ray diffraction (XRD) patterns, show the nanoparticulated character of those solids obtained at low temperatures, with typical particle sizes in the 10–20 nm range when prepared at 673 K. The UV–Vis results indicate both the insertion of V in the anatase lattice and the feasibility of nitridation at low temperatures. The photocatalytic properties of these materials (as prepared and after their incorporation to mortar samples) in the degradation of nitrogen oxides have been preliminary evaluated. Although N‐doping enhances the photocatalytic activity of the TiO₂ matrix, V‐doping worsens it.     

Decomposition of gas‐phase aromatic hydrocarbons by applying an annular‐type reactor coated with sulfur‐doped photocatalyst under visible‐light irradiation

BACKGROUND: Unlike many water pollution applications, visible‐light‐driven photocatalysis of gas‐phase pollutants has been reported only rarely. The present study was performed to investigate the feasibility of applying S‐doped visible‐light‐induced TiO₂ to treat gas‐phase aromatic hydrocarbons, using a continuous air‐flow annular‐type reactor. RESULTS: The prepared S‐enhanced TiO₂ powders, along with a commercially available TiO₂ powder (Degussa P‐25), were characterized using diffuse reflectance UV‐VIS‐NIR spectrophotometry, Fourier transform infrared (FTIR) spectrophotometry, X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetry (TG) analyses. A photocatalytic activity test exhibited an increasing trend in degradation reaction rates with increase in flow rate but a decreasing trend in terms of degradation efficiencies. Several experimental conditions induced reasonably high decomposition efficiencies with respect to toluene, ethyl benzene and o,m,p‐xylenes (close to or above 90%), although benzene exhibited a somewhat lower decomposition efficiency. CONCLUSIONS: The S‐doped TiO₂ and undoped P25 TiO₂ powders exhibited different catalyst characteristics. The results demonstrate that an annular‐type reactor coated with visible‐light‐activated S‐doped TiO₂ can serve as an effective tool to treat gas‐phase aromatic hydrocarbon streams. Copyright © 2009 Society of Chemical Industry     

UV–Visible Light Driven Photocatalytic Degradation of Ciprofloxacin by N,S Co-doped TiO2: The Effect of Operational Parameters

Photocatalytic degradation using TiO₂ is one of the most effective techniques for treating residual emerging compounds present in water. However, practical applications are limited since it only absorbs ultraviolet irradiation. Nitrogen and sulfur (N, S) co-doped TiO₂ nanomaterials (N,S-TiO₂) were prepared by a controlled sol–gel method; the characterization and photocatalytic activity have been studied for the removal of ciprofloxacin antibiotic under UV–Visible light. The interstitial doping of nitrogen and sulfur substitute oxygen and titanium into the TiO₂ lattice, which increases the valence band and decreases the conduction band, respectively. The lowest value band-gap of 2.5 eV and the crystallite size of 5.13 nm compared to other available synthesis methods was observed on N,S-TiO₂ which allowed to broaden the light absorption to the visible region. The low level electron and hole recombination was related by the N, S doping. The optimal ciprofloxacin removal was obtained at pH 5.5, a dosage of 0.05 g, initial concentration of 30 mg L^?1 with a removal efficiency of 78.7%. A comparison of the effectiveness of antibiotic treatment of N,S-TiO₂ with synthetic TiO₂ and commercial TiO₂ was also made, taking the potential for regeneration into account. The photocatalytic degradation of ciprofloxacin catalyzed by N,S-TiO₂ was described by pseudo-first-order kinetics.

     

Visible-light photoactivity of hierarchical porous carbon supported N-doped TiO2

Hierarchical porous carbon fabricated from biomass provides an effective support for catalysts. Nitrogen doped TiO₂ particles (50?nm in size) synthesized from titanium tetraethoxide were loaded uniformly on the porous carbons carbonized from Zizania latifolia leaves by a sol?Cgel method. X-Ray diffraction and Auger Electronic Spectrometer analysis indicated that nitrogen atoms were doped into anatase TiO₂ lattices. The bandgap of the nitrogen doped TiO₂ derived from the light absorption spectrum was about 3.05?eV. The nitrogen doped TiO₂ on the hierarchical porous carbon hybrid photocatalysts showed a high degradation rate of 2-propanol in water with visible light irradiation.     

Preparation and characterization of TiO2 photocatalysts by Fe doping together with Au deposition for the degradation of organic pollutants

Fe³⁺ doped TiO₂ deposited with Au (Au/Fe–TiO₂) was successfully prepared with an attempt to extend light absorption of TiO₂ into the visible region and reduce the rapid recombination of electrons and holes. The samples were characterized by X-ray diffraction (XRD), N₂ physical adsorption, Raman spectroscopy, atomic absorption flame emission spectroscopy (AAS), UV–vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectra. The photocatalytic activities of the samples were evaluated for the degradation of 2,4-chlorophenol in aqueous solutions under visible light (λ > 420 nm) and UV light irradiation. The results of XRD, XPS and high-resolution transmission electron microscopy (HRTEM) analysis indicated that Fe³⁺ substituted for Ti⁴⁺ in the lattice of TiO₂, Au existed as Au⁰ on the surface of the photocatalyst and the mean particle size of Au was 8 nm. Diffuse reflectance measurements showed an extension of light absorption into the visible region for Au/Fe–TiO₂, and PL analysis indicated that the electron–hole recombination rate has been effectively inhibited when Au deposited on the surface of Fe-doped TiO₂. Compared with Fe doped TiO₂ sample and Au deposited TiO₂ sample, the Au/Fe–TiO₂ photocatalyst exhibited excellent visible light and UV light activity and the synergistic effects of Fe³⁺ and Au was responsible for improving the photocatalytic activity.     

Synthesis of Nanoparticulate In‐Doped BiVO4 for Enhanced Visible‐Light Photocatalytic Degradation of Dye

Indium (2.9, 3.5, and 4.9 at. %)‐doped and pristine monoclinic BiVO₄ nanoparticles were synthesized by hydrothermal method. They were characterized by high‐resolution scanning electron, field emission scanning electron, transmission electron and high‐resolution transmission electron microscopies, powder X‐ray and selected‐area electron diffractometries, energy‐dispersive X‐ray, Raman, UV‐visible diffuse reflectance, photoluminescence, and solid‐state impedance spectroscopies. The band gap and near‐band‐gap emission of 4.9% In‐doped BiVO₄ nanoparticles are larger than those of the rest of the nanomaterials. The charge‐transfer resistance of 4.9% In‐doped BiVO₄ is the least. In‐doping enhances visible‐light photocatalytic activity.     

Photoactive behavior of polyacrylonitrile fibers based on silver and zirconium co‐doped titania nanocomposites: Synthesis,characterization, and comparative study of solid‐phase photocatalytic self‐cleaning

Silver and zirconium co‐doped and mono‐doped titania nanocomposites were synthesized and deposited onto polyacrylonitrile fibers via sol–gel dip‐coating method. The resulted coated‐fibers were characterized by X‐ray diffraction (XRD), scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, diffuse reflectance spectroscopy, thermogravimetric analysis, and BET surface area measurement. Photocatalytic activity of the TiO₂‐coated and TiO₂‐doped coated fibers were determined by photomineralization of methylene blue and Eosin Y under UV–vis light. The progress of photodegradation of dyes was monitored by diffuse reflectance spectroscopy. The XRD results of samples indicate that the TiO₂, Ag‐TiO₂, Zr‐TiO₂, and Ag‐Zr‐TiO₂ consist of anatase phase. All samples demonstrated photo‐assisted self‐cleaning properties when exposed to UV–vis irradiation. Evaluated by decomposing dyes, photocatalytic activity of Ag–Zr co‐doped TiO₂ coated fiber was obviously higher than that of pure TiO₂ and mono‐doped TiO₂. Our results showed that the synergistic action between the silver and zirconium species in the Ag‐Zr TiO₂ nanocomposite is due to both the structural and electronic properties of the photoactive anatase phase. These results clearly indicate that modification of semiconductor photocatalyst by co‐doping process is an effective method for increasing the photocatalytic activity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis of Ni doped barium hexaferrite by microemulsion route to enhance the visible light-driven photocatalytic degradation of crystal violet dye

The pristine and Ni doped BaNi_xFe_12-xO₁₉ (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) NPs have been fabricated via facile microemulsion approach and the impact of dopants was explored based dielectric, optical, structural and the photocatalytic properties of BaNi_xFe_12-xO₁₉ nanoparticles. X-ray diffraction and Raman study confirmed the formation of regular hexagonal geometry with space group P6₃/mmc with crystallite size in 32–50 nm range. Functional groups were identified using FTIR analysis. The remanence (Pr), saturation polarization (Ps) and coercivity (Hc) was explored by P-E loop analysis and the value of Pr and Ps was enhanced with the concentration of dopant. According to PL spectra, highly doped materials had a higher charge separation (e^?- h⁺) and low recombination rate, which resulted in higher photocatalytic degradation activity of fabricated nanomaterials. The optical band gap was found to be 1.78 eV versus undoped (2.60 eV for pristine BaFe₁₂O₁₉). Due to polarizations, the dielectric loss, dielectric constant and tangent loss values were declined, while AC conductivity was enhanced. Photocatalytic performance of doped and undoped samples under visible right irradiation was studied for crystal violet dye. For 100 min exposure to visible light, the highly doped catalyst exhibits 97% degradation versus 60% in case of pristine this is attributed to efficient electron-hole pair separation. Furthermore, quenching effect of different scavengers indicated that hydroxyl radical had a main role, and e^? or h⁺ played a minimal role in CV dye degradation. The enhanced properties due to doping make BaNi_xFe_12-xO₁₉ a potential candidate for photocatalytic applications under visible light irradiation.     

Characterization of Mo Doped TiO2 and its Enhanced Photo Catalytic Activity Under Visible Light

Transition metal doping into the TiO₂ lattice can expand the response of these metal oxide nano particles to the visible region. In view of this, Mo⁶⁺ ion is doped into the TiO₂ lattice in order to understand the mechanism of its photo response. The prepared photocatalysts were characterized by X-ray diffraction, UV–Visible absorption spectroscopy, UV–Visible diffuse reflectance spectroscopy, SEM, EDX, FTIR and BET specific surface area techniques. The characterization results have confirmed the incorporation of metal ions into TiO₂ lattice. XRD analysis shows no change in crystal structure except a slight variation in crystallite size and elongation along the c-axis with increase in the concentration of the dopant. Diffuse reflectance measurements showed a shift in the band edge position to longer wavelengths and an extension of the absorption to the visible region. The photo degradation efficiencies of these catalysts were studied with Tebuconazole pesticide as model pollutant. Under UV light, undoped catalyst showed higher activity than doped catalyst. But in the case of visible light irradiation Mo doped TiO₂ with intermediate dopant concentration of 0.06 atom % had the highest photocatalytic reactivity. This may be due to the narrowing of band gap so that it could effectively absorb the light of longer wavelength. The degradation path way was followed by UV–Visible spectroscopy.     

The photo-catalytic activities of neodymium and fluorine doped TiO2 nanoparticles

A series of photo-catalysts were synthesized by neodymium and fluorine doped TiO₂, and their characteristics evaluated by X-ray diffraction (XRD), UV–vis diffuse reflectance spectra (UV–vis), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Neodymium and fluorine doped TiO₂ has obvious absorption in the visible light and the absorption edge shifts toward red wavelength. In addition, compared with pure TiO₂, the doped catalyst has intense absorption at 528, 587, 750, 808, and 881 nm. The catalytic efficiency was tested by monitoring the photo-catalytic degradation of methylene blue (MB) in visible light and ultraviolet light. The results showed that the optimum doping content was Nd:F:TiO₂ = 0.5:5:100 (molar ratio) heat treated at 500 °C, and the reaction rates of MB degradation were estimated to be about 1.76 times and 1.45 times higher than undoped TiO₂ in ultraviolet light and visible light.