Molar Ratio Of TiO2 Research Articles

Enhancement of Photoelectric Conversion Efficiency in Dye-Sensitized Solar Cells Using SnO2–TiO2 Composite Nanofibers

SnO2 is a wide-band gap N-type semiconductor material with a higher electron transfer rate than TiO2. Therefore, SnO2 has broad application prospects in the photoanode composite materials of dye-sensitized solar cells (DSSC). In this study, SnO2–TiO2 composite nanofibers with different molar ratios (5%, 10%, 15%, and 20%) were prepared by double-needle electrospinning technology, and the nanofibers were characterized after adjusting the solution composition. Different molar ratios of TiO2 and SnO2–TiO2 composite nanofiber photoanodes were fabricated by spin-coating, and the adsorption behavior of dyes on the photoanodes was investigated. Moreover, the electrochemical impedance of the photoanodes and DSSC and their photoelectric performance were also tested. The experimental results showed that SnO2–TiO2 composite nanofibers with a molar ratio of 10% exhibited excellent properties, including a peak specific surface area of 93.01 m2/g, strong dye adsorption capacity, small interfacial resistance, and fast electron transfer rate. These outstanding properties significantly promoted the generation of photoelectrons and improved the photoelectric conversion efficiency of DSSC. Compared with single-component TiO2, the photoelectric conversion efficiency of SnO2–TiO2 nanofiber photoanode composite material improved by 85.65%.

S-scheme TiO2/Bi2WO6 heterojunction for enhanced photocatalytic selective oxidation of toluene

Selective activation of saturated C–H bonds in hydrocarbons, such as the activation of the C–H bond in toluene, is an effective method for the production of high value-added chemicals. However, improving the C–H bond activation of toluene remains a challenge. In this study, S-scheme TiO2/Bi2WO6 composites were synthesized by loading TiO2 nanoparticles on Bi2WO6 flakes using a simple hydrothermal method. The physical and chemical properties of the prepared materials were characterized using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectoscopy (FT-IR), Scanning Electronic Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS) and other characterization methods. Selective oxidation of toluene to benzaldehyde under visible light irradiation using air as an oxidizing agent. When the molar ratio of TiO2 and Bi2WO6 was 0.20, the composites exhibited excellent photocatalytic performance with a benzaldehyde production rate of 1725.41 μmol g−1 h−1, which was 2.31 and 1.91 times higher than that of TiO2 and Bi2WO6, respectively. This excellent performance is attributed to the formation of heterojunction structure by the loaded TiO2 nanoparticles, which improves the separation efficiency of photogenerated carriers and thus enhances its photocatalytic performance. In addition, the active substances involved in the photocatalytic reaction were identified by free radical trapping experiments as ·O2− and h+. Finally, the photocatalytic mechanism of S-scheme TiO2/Bi2WO6 composites was proposed by energy band structure analysis and radical trapping experiments. This study provides a simple design pathway for the construction of visible-light responsive bismuth tungstate-based heterojunction photocatalysts and some ideas for the development of new and efficient photocatalytic toluene selective oxidation catalysts.

Research upon Cu-Doping Contents in TiO2 Nanoparticles Incorporated onto Cellulose Nanofibers for Dye Removal and Self-Cleaning Applications.

Cu-doping contents in the TiO2 lattice structure were studied to show the effects on the crystal structure, morphology, and photocatalytic activity of TiO2 nanoparticles and thus composite cellulosic nanofibrous membranes. Pristine and copper-doped TiO2 nanoparticles were synthesized using the sol-gel technique, a wet chemical method with the advantages of low synthesizing temperature, uniform nanosize distribution, and purity. The as-synthesized semiconductor nanoparticles were first tested with the dye removal process and then impregnated onto electrospun cellulose nanofibers (CL nanofibers) to acquire modified nanofibers with self-cleaning properties. The as-prepared composite CL nanofibers consisting of doped and undoped TiO2 nanoparticles were characterized by various techniques, such as field emission scanning electron microscopy, transmission electron microscopy, UV-vis, X-ray diffraction, Fourier transform infrared spectroscopy, and tensile tests. The copper-doped TiO2 molar ratio in the nanocomposite was found to possess a pronounced impact on the dye removal and self-cleaning effects under the visible light spectrum, whereas TiO2 is highly effective under specific UV-light irradiation. Optical measurements and dye decomposition showed that the Cu-doped TiO2 nanocomposite was optimized at a 1% molar ratio by the copper-doping concentration regarding dye removal and self-cleaning applications under the visible light range.

HfTiO4 transparent thick film phosphors activated with Eu3+, Dy3+, and Tb3+ ions

Hafnium (Hf)-based double oxides show promise as high-efficiency scintillators due to large effective atomic numbers and high relative density. However, the preparation of these scintillation crystals is challenging due to their high melting points and incongruent melting behavior. In the present study, we demonstrated that the chemical vapor deposition (CVD) of single-phase HfTiO4 films on quartz glass substrate was successfully deposited at temperatures ranging from 973 to 988 K, with a TiO2 molar ratio in the precursor vapor of 25–45 mol% TiO2. The deposition rate of HfTiO4 reached 36 µm h−1. The films exhibited an in-line transmittance of 78 % relative to the raw glass substrate at a wavelength of 600 nm. When activated with Eu3+, Dy3+, and Tb3+ ions, the HfTiO4 films displayed red, yellow, and green photoluminescence emissions originated from the 4f–4f transitions of each trivalent rare-earth ion under ultraviolet light irradiation. HfTiO4 exhibited no intrinsic background emission, suggesting that the addition of a selected activator could yield a phosphor with the desired emission color range.

Thulium-doped titanate-germanate glasses for infrared photonics

In this paper, we performed a comparative spectroscopic analysis of Tm3+-doped glasses based on GeO2-BaO-Ga2O3 (GBG) and TiO2-GeO2-BaO-Ga2O3 (TGBG) to achieve broadband luminescence at 1.8 μm. Glasses were prepared at different doping concentrations (0.05 mol% and 1mol%) in order to investigate the effect of Tm3+ ions as well as host composition (GeO2:TiO2 molar ratios) on near-IR luminescence properties. We report on the hypersensitivity of the transition 3H6 → 3F4 of Tm3+ in a series of titanate-germanate glasses, which was shifted to longer wavelengths with increasing TiO2 concentration. The relative intensity of the main near-IR emission band corresponding to the 3F4 → 3H6 (1.8 μm) transition of Tm3+ was 4.8-fold enhanced for glass with molar ratio GeO2:TiO2 = 1:5 compared to GBG glass system. We observed the luminescence quenching phenomena for samples containing more than 0.5 mol% of Tm3+ ions. The calculated spectroscopic parameters, such as measured luminescence lifetime (τm) and the quantum efficiency (η), were discussed and compared to the different laser glasses. Importantly, luminescence decay curves have been examined using the Inokuti-Hirayama model. Additionally, the correlation between optical properties and local structure in glasses was well evidenced by Raman spectroscopy. The proposed strategy, in combination with various chemical composition of glass host activated by various Tm2O3 concentration, might be beneficial for modern near-infrared photonics.

Enhanced Alkaline Hydrogen Evolution on Gd1.0/Ndx (x = 0.5, 1.0, 3.0, and 6.0%)-Doped TiO2 Bimetallic Electrocatalysts

The work reports a facile synthesis of high thermally stable nanocrystalline anatase TiO2 nanoparticles (NPs) doped with different atomic concentrations (0.5, 1.0, 3.0, and 6.0%) of Gd3+ and Nd3+ ions by a template-free and one-step solvothermal process, using titanium(IV) butoxide as a titanium precursor and dimethyl sulfoxide (DMSO) as a solvent. The structure and morphology of the Gd3+, Nd3+, and 0.5%Gd3+-0.5%Nd3+/doped TiO2 NPs have been characterized by using various analytical techniques. The Gd3+/ and Nd3+/TiO2 molar ratios were found to have a pronounced impact on the crystalline structure, size, and morphology of TiO2 NPs. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) studies revealed the proper substitution of Ti4+ by Gd3+ and Nd3+ ions in the TiO2 host lattice. The as-prepared Gdx/TiO2, Ndx/TiO2, and Gd1.0/Ndx/TiO2 bimetallic NPs, x = 0.5, 1.0, 3.0, and 6%, have been investigated as electrocatalysts for hydrogen evolution reaction (HER) in 1.0 M KOH solution using a variety of electrochemical techniques. At any doping percentage, the Gd1.0/Ndx/TiO2 bimetallic NPs showed higher HER catalytic performance than their corresponding counterparts, i.e., Gdx/TiO2 and Ndx/TiO2. Upon increasing the Nd content from 0.5 to 6.0%, the HER catalytic performance of the Gd1.0/Ndx/TiO2 bimetallic NPs was generally enhanced. Among the studied materials, the bimetallic Gd1.0/Nd6.0/TiO2 NPs emerged as the most promising catalyst with an onset potential of −22 mV vs. RHE, a Tafel slope of 109 mV dec−1, and an exchange current density of 0.72 mA cm−2. Such HER electrochemical kinetic parameters are close to those recorded by the commercial Pt/C (onset potential: −15 mV, Tafel slope: 106 mV dec−1, and exchange current density: 0.80 mA cm−2), and also comparable with those measured by the most active electrocatalysts reported in the literature. The synergistic interaction of Gd and Nd is thought to be the major cause of the bimetallic catalyst’s activity.

Improved Adsorption and Photocatalytic Degradation of Methyl Orange by Onion-like Nanocarbon/TiO2 Nanocomposites

Waste cooking oil, a known environmental pollutant, has been used as a precursor for the synthesis of onion-like nanocarbons (OLNCs) using flame pyrolysis. The OLNCs were added to TiO2 to form TiO2/OLNC nanocomposites through hydrothermal treatment. The TiO2/OLNCs ratio was varied by increasing the mass of the OLNCs (10, 20, 30, and 50 mg), while the mass of TiO2 (100 mg) was kept constant at C to TiO2 molar ratios of 1:2, 1:4, 1:6, and 1:10, respectively. The surface area of the photocatalysts increased with an increase in the mass of OLNCs. The nanocomposites were applied in the photocatalytic degradation of methyl orange. The photocatalysts showed a degradation efficiency trend of TC-10 > (99.9%) TC-20 > (90%) TC-30 > (81%) TC-50 > (70%) TiO2 (44%) in 120 min. A similar trend was observed from the first-order kinetic rate data. The degradation efficiency of methyl orange was improved by adding 5% H2O2 (99.9%) in 30 min. The OLNCs were responsible for increased photocatalytic activity due to a high adsorption efficiency compared to pure TiO2. The OLNCs acted as an electron acceptor, while the TiO2 acted as an electron donor. The enhanced catalytic behavior was achieved by hindering the recombination of e−/h+ in the composite and increasing the adsorption capability of TiO2.

Multi-functional silver nanoprism-titanium dioxide hybrid nanoarrays for trace-level SERS sensing and photocatalytic removal of hazardous organic pollutants

Owing to the excellent optoelectronic properties of metal nanoparticle-semiconductor interfaces; hybrid substrates with superior catalytic and sensing properties can be designed. In the present study, we have attempted to evaluate anisotropic silver nanoprisms (SNP) functionalized titanium dioxide (TiO2) particles for multifunctional applications such as SERS sensing and photocatalytic decomposition of hazardous organic pollutants. Hierarchical TiO2/SNP hybrid arrays have been fabricated via facile and low-cost casting techniques. The structural, compositional, and optical characteristics of TiO2/SNP hybrid arrays were well elucidated and correlated to SERS activities. SERS studies revealed that TiO2/SNP nanoarrays possess almost 288 times enhancement compared to bare TiO2 substrates and 2.6 times enhancement than pristine SNP. The fabricated nanoarrays demonstrated detection limits down to 10-12 M concentration levels and lower spot-to-spot variability of ∼ 11%. The photocatalytic studies showed that almost 94 and 86% of rhodamine B and methylene blue were decomposed within 90 min of visible light exposure. Besides, two times enhancement in photocatalytic activities of TiO2/SNP hybrid substrates was also observed than bare TiO2. The highest photocatalytic activity was exhibited by SNP to TiO2 molar ratio of 1.5 × 10-3. The electrochemical surface area and the interfacial electron-transfer resistance were increased with the increment in TiO2/SNP composite load from 3 to 7 wt%. Differential Pulse Voltammetry (DPV) analysis revealed a higher RhB degradation potential of TiO2/SNP arrays than SNP or TiO2. The synthesized hybrids exhibited excellent reusability without any significant deterioration in photocatalytic properties over five successive cycles. TiO2/SNP hybrid arrays were proved to be multiple platforms for sensing and degrading hazardous pollutants for environmental applications.

Spectroscopic Properties of Pr3+, Tm3+, and Ho3+ in Germanate-Based Glass Systems Modified by TiO2

In this paper, the effect of the GeO2:TiO2 molar ratio in glass composition on the spectroscopic properties of germanate glasses was systematically investigated. The visible luminescence bands associated with characteristic 1D2 → 3H4 (red), 5S2, 5F4 → 5I8 (green), and 1D2 → 3F4 (blue) transitions of Pr3+, Ho3+, and Tm3+ ions in systems modified by TiO2 were well observed, respectively. It was found that the luminescence intensity of glasses containing Pr3+ and Ho3+ ions increases, whereas, for Tm3+-doped systems, luminescence quenching with increasing content of TiO2 was observed. Based on Commission Internationale de I'Eclairage (CIE) chromaticity coordinates (x, y) analysis, it was demonstrated that the value of chromaticity coordinates for all glasses depends on the GeO2:TiO2 molar ratio. The addition of TiO2 to system compositions doped with Tm3+ ions shifts the (x, y) to the center of the CIE diagram. However, chromaticity coordinates evaluated for glasses containing Pr3+ ions move to a purer red color. Our results confirm that the spectroscopic properties of the studied glasses strongly depend on TiO2 content. Moreover, it can be stated that germanate-based glass systems modified by TiO2 can be used for optoelectronics in RGB technology as red (Pr3+), green (Ho3+), and blue (Tm3+) emitters.

Statistical optimization of process conditions for pyrvinium pamoate elimination using UV/zeolite‐based nanostructures/H 2 O 2

Statistical optimization of process conditions for pyrvinium pamoate elimination using UV/zeolite‐based nanostructures/H ₂ O ₂

Influence of resorcinol–formaldehyde resin on the formation of alkali titanate fibers

Nowadays, alkali titanate (ATO) fibers are attracting attention because they can provide a reinforcing as well as a functional effect. In this study, ATO fibers were synthesized by a one-step calcination route without specialized equipment and flux using a resorcinol–formaldehyde (RF) resin. Homogeneous mixing of the RF resin dissolved in water, TiO 2 , and an alkali source led to a uniform dispersion, and the three-dimensional polymerized RF resin formed a closely structured matrix with TiO 2 and the alkali source. By carbonizing the RF resins prepared using K or Na as the alkali source, titanate fibers with lengths greater than 1 mm were formed. Growth mechanisms and crystal structures of the titanate fibers synthesized with and without the RF resin were completely different. Effects of the RF resin on the crystal structure and morphology of the titanate fibers were systematically studied by changing the calcination temperature and molar ratio of TiO 2 and alkali source (Li, Na, or K). We found that the RF resin played an essential role in producing a suitable reaction field for fiber growth and controlling the morphology of titanate fibers. • Titanate fibers can be easily synthesized by a one-step calcination process. • Resorcinol-formaldehyde (RF) resin was applied as a carbon source. • RF resin gives significant effects on the growth mechanisms of the fiber. • The surface exposed by the decomposition of RFC acts as a reaction field. • The exposed surface is also important for uniform fiber formation.

Preparation of double-layer two wavelength infrared antireflective coating on CdSe substrate

Designing and fabrication of the infrared antireflection coatings are quite important for the application of infrared optical elements. Herein, double-layer two wavelength infrared antireflective (AR) coating was prepared on CdSe substrate by sol-gel method, in which the bottom layer is porous TiO2 film and the top layer is SiO2 nanoparticle film containing a small amount of TiO2 (molar ratio of Si/Ti is 7.7). The reflectivity of the coated sample is about 2.1% at 2000 nm and 2.8% at 2500 nm, respectively, and the average reflectivity of the whole wide band from 1800 nm to 2600 nm is about 2.6%, which is about 27% lower than that of uncoated CdSe substrate. By adding reasonable additives and designing the film structure, the problem that thick infrared film is not resistant to high temperature annealing was solved. Moreover, the AR coating shows a super hydrophilicity, which can avoid the influence of water mist condensation on the transmittance. Importantly, this AR coating exhibits a good thermal shock resistance, and the reflection spectrum of the film did not change after ten thermal shock cycles at 400 °C, which meaning this film can be expected to meet the requirements of high temperature irradiation environment. This work provides important guidance for the preparation of infrared AR film with high thermal stability.

Fabrication of TiO2/CdS heterostructure photoanodes and optimization of light scattering to improve the photovoltaic performance of dye-sensitized solar cells (DSSCs)

Currently, the TiO2/CdS photoanodes based dye-sensitized solar cells (DSSCs) have shown extraordinary developments in the photo-conversion efficiency. In this report, pristine TiO2, CdS and various molar ratios of TiO2/CdS photoanodes were prepared by one step microwave irradiation route and followed by doctor blade method. The sheet-like morphology of the TiO2 and CdS nanoparticles were clearly evident from the SEM and TEM images. A significant reduction bandgap with enhanced light absorption and rapid prevention of electron hole pair was explored by UV-DRS and PL studies. The photocurrent density–voltage (J–V) and electrochemical impedance (EIS) characteristics were analyzed for assembled solar cell. The photo-conversion efficiency of 12.8% was obtained with the configuration TiO2/CdS (200 mg) that represent a 2.5-fold increment compared to bare TiO2 (5.33%) as well as commercial Pt (6.11%). The experimental results are discussed.

Enhanced photocatalytic degradation performance of bisphenol A over TiO<sub>2</sub>-SiO<sub>2</sub> photocatalyst by improving specific surface area under simulation natural light

The application of natural light in photocatalytic process is a potential energy source. In this study, TiO2-SiO2 nanoparticles with outstandingly enhanced photocatalytic activity have been fabricated by sol-gel method. The prepared photocatalysts with different molar ratio of TiO2:SiO2 as 100:0; 95:5; 85:15 and 75:25 were denoted as TiO2, TS5, TS15 and TS25, respectively. Characterization of these photocatalysts was evaluated using transmission electron microscopy (TEM), X-ray diffraction (XRD), N2 Adsorption and Desorption isotherms method (Brunauer–Emmet–Teller, BET). The specific surface area was improved in TiO2-SiO2 photocatalyst namely 193.9 m2.g-1 (at molar ratio of TiO2:SiO2 of 95:5) compared to 33.6 m2.g-1 of TiO2. The crystallite size was calculated around 5 nm from XRD data and uniform particle size distribution was observed in TEM image. The photocatalytic experiments were performed with bisphenol A (BPA) as model compound of organic pollutant. The effect of various operation parameters such as initial concentration, initial solution pH and photocatalyst dosage has been investigated. The kinetic studies of the photocatalytic degradation BPA over TS5 followed the pseudo-first order (k=1.09×10-2 min-1) and degradation yield to be 82.4% BPA, at pH6.23, initial concentration to be 10 ppm and photocatalyst dosage to be 1.0 g.L-1. The photocatalyst TS5 maintained activity after four cycles and remained 78%. The TiO2-SiO2 composite photocatalyst has shown to be a promising heterogeneous photocatalyst for organic degradation.

TiO2–ZnO nanocomposites: synthesis, linear and nonlinear optical analysis

TiO2–ZnO binary heterojunctions with different molar ratios of TiO2 to ZnO have been prepared via a two-step co-precipitation method, including the synthesis of TiO2 nanoparticles (NPs) and then incorporating them into the ZnO matrix. Structural studies and elemental analysis have been carried out by a series of characterization techniques including X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectrometer. The linear optical characteristics have been investigated using photoluminescence emission spectra at an excitation wavelength of 300 nm to estimate various energy states formed in crystalline structures. The optical nonlinearities of synthesized NPs have been tested by nanosecond laser pulse-based single-beam Z-scan technique. Closed-aperture and open-aperture Z-scan measurements have shown negative lens effects and reverse saturable absorption behaviours for as-synthesized composite nanostructures, respectively. The third-order susceptibilities of TiO2–ZnO nanocomposites have been estimated to be higher than that of pristine TiO2 NPs with a maximum value of 4.8 × 10−4 esu belonging to the sample with a 1:1 molar ratio of TiO2 to ZnO.

Synthesis of Perovskite by Solid-Phase Method with Metatitanic Acid and Calcium Carbonate and Its Pigment Properties Investigation.

Synthetic perovskite powder (SPP) was synthesized by the solid-phase method using metatitanic acid (TiO2·nH2O) and calcium carbonate (CaCO3) as raw materials, and its structure, morphology, pigment properties and application in architectural coatings were studied. When TiO2·nH2O and CaCO3 were mixed and ground at a molar ratio of TiO2:CaO = 1:1, and then calcined at 900–1100 °C, SPP with a single perovskite phase was obtained. The characterization results displayed that the unit particle size of SPP was 50–150 nm, the aggregate size was 1–2 μm, and its particles were well dispersed. The SPP also had a whiteness of 90.5%, and an oil absorption of 35.03 g/100 g. The hiding power of SPP was 24.02 g/m2, which was 81.6% of pure TiO2 hiding power (19.60 g/m2). When adding SPP to prepare a building exterior wall coating, the contrast ratio of the coating film was 0.92, which met the requirements of the Chinese national standard GB/T 9755-2014 and was equivalent to adding rutile titanium dioxide. Thus, perovskite synthesized from TiO2·nH2O and CaCO3 by the solid-phase method significantly improved the pigment properties of TiO2 in the same proportion.

Preparation and Photocatalytic Hydrogen Production Properties of Mesoporous CdS/TiO2 Composites

The mesoporous CdS/TiO2 composites were synthesized by a sol–gel method combined with solvothermal method. The material showed the gel block-like structures which were composed of heterogeneous spherical gel particles, the average size of the particles was about 14[Formula: see text]nm, with specific surface area as 300.254[Formula: see text]m2[Formula: see text]g[Formula: see text]. The mesoporous CdS/TiO2 composites exhibited a wide absorption band to simulated sunlight whose adsorb wavelength reached to 550[Formula: see text]nm, its absorption intensity and catalytic performance of photocatalytic water-producing hydrogenation were also increased with the increase of CdS contents. When the molar ratio of TiO2:CdS was 1:1, the photocatalytic activity reached the highest, and the average hydrogen production rate reached 2167.32[Formula: see text][Formula: see text]mol[Formula: see text]g[Formula: see text][Formula: see text]h[Formula: see text].

Low-Temperature Processed TiO2 Nanoparticle Layer with Inorganic Binder for Perovskite Solar Cell

In this study, we report on the low-temperature (<120 °C) fabrication of a mesoporous titanium dioxide (TiO2) layer for use in perovskite solar cells. The TiO2 layer used was produced from a solution of TiO2 nanoparticles, purified water and titanium isopropoxide (TTIP) acting as a precursor of an inorganic binder network. We compared the properties of TiO2 layers resulting from different molar ratios (ranging from 0.1:1∼0.5:1) of titanium isopropoxide to TiO2 nanoparticles. Finally, perovskite solar cells were fabricated based on our optimized TiO2 molar ratio (TTIP:TiO2 = 0.1:1) and found to exhibit a short-circuit current density of ∼16.01 mA cm–2 and photoelectric conversion efficiency of ∼5.57%, respectively.

Novel direct Z-scheme AgI/N–TiO2 photocatalyst for removal of polluted tetracycline under visible irradiation

In the study, we doped N into TiO2 lattice to narrow its band gap energy. Then, the synthesized N doped TiO2 material was combined with AgI to form AgI/N–TiO2 (ANT) direct Z scheme materials. The synthesized materials were utilized for photocatalytic removal of tetracycline (TC) using visible irradiation as an excitation source. We also conducted radical scavenging experiments to determine photocatalytic degradation mechanism. We investigated that these photo-excited electrons (e−) in N–TiO2 conduction band tended to combine with the left holes (h+) in AgI valence band maintaining h+ in the valence band of the N–TiO2 and e− in the conduction band of the AgI. The remained e− and h+ have high redox potential to initiate for photocatalytic decomposition of TC. Thus, the TC degradation by the ANT materials were significant greater than those by single components (AgI or N–TiO2). We also investigated that the TC degradation by the ANT-30 material, which the AgI: N–TiO2 molar ratio was 30%, exhibited that highest degradation efficiency. Finally, the ANT photocatalyst exhibited excellent stability during TC degradation processes supporting for its promising potential application in practical systems.

Photocatalytic performance of mesoporous composites of TiO2–ZrO2 and phosphotungstic acid

Herein, the mesoporous composite materials, mTiO2–ZrO2/PTAy-x (PTA = phosphotungstic acid, x represents the molar ratio of Ti to Zr, y represents the weight percent of PTA in mTiO2–ZrO2/PTA samples), have been prepared by the surfactant-assisted sol–gel method combined with a subsequent hydrothermal treatment. The as-prepared catalysts were fully characterized by FT-IR, XRD, SEM, TEM, XPS, DRS, PLs and nitrogen adsorption–desorption techniques. The results indicated that mTiO2–ZrO2 sample with the TiO2 and ZrO2 molar ratio of 3 exhibits good crystallinity, large internal surface areas and narrow-sized pores. The PTA clusters incorporated in mTiO2–ZrO2 frameworks preserve intact Keggin structure according to EDX, FT-IR and diffuse reflectance UV/vis/NIR spectroscopy. The band gap energy of as-prepared composites is reduced compared with single components. The PL experiments revealed that the obtained mTiO2–ZrO2 can strongly retard the recombination of photogenerated electrons and holes compared with a single oxide, and the introduction of PTA species can further improve the light adsorption and the photochemical stability, therefore efficiently promoting photocatalytic activity of the ternary composite materials. Photocatalytic experiments confirmed that mTiO2–ZrO2/PTA10-3 displayed highly efficient and durable activity for the photodegradation of methyl orange under simulated sunlight and photoreduction of Cr(VI) under visible light. The study of the photocatalytic mechanism revealed that superoxide radicals (∙O2−) and holes (h+) are the main active species. These materials are very stable in the photocatalytic reactions, and therefore, they are promising and efficient catalysts for practical applications.