Hydrothermal in situ preparation of phthalocyanine–TiO2 nanocomposites for photocatalytic activity under visible light irradiation

Research on Chemical Intermediates - In this study, phthalocyanine (Pc)–TiO2 nanocomposites were prepared via in situ hydrothermal method. The metal-free, zinc(II), cobalt(II), nickel(II) and...     

Two bimetallic metal–organic frameworks capable of direct photocatalytic degradation of dyes under visible light

Transition Metal Chemistry - Two bimetallic metal–organic frameworks (MOFs), specifically {2[LiM(TDA)2(DMF)]·NH2+(CH3)2}n (M?=?Co (HNU-29) or Zn (HNU-30),...     

Adsorption properties and photocatalytic activity of TiO2 and La-doped TiO2

Photocatalysts of TiO₂ and La-doped TiO₂ were prepared by calcining the pure TiO₂ sols and the sols mixed with La(NO₃)₃⋅6H₂O at 873 K, respectively. These photocatalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and N₂ adsorption-desorption isotherms measurement. As results, the BET surface area, pore diameter, mesopore volume and micropore volume slightly increased, while the crystallite size and the phase structure were little affected by lanthanum doping. The equilibrium adsorption of methylene blue (MB) on the photocatalysts were measured in a dark room. The adsorption isotherms were confirmed to fit to the Langmuir theory. Photocatalytic activities of the photocatalysts were studied by employing the photocatalytic degradation of MB in water and degradation of acetaldehyde in air under UV-irradiation using a black light. Kinetic analysis revealed that the rate controlling steps could be the surface reaction of the adsorbed MB on the catalyst surface for MB degradation and the reaction of adsorbed acetaldehyde with the gaseous acetaldehyde for degradation of acetaldehyde, respectively.     

Visible light photocatalytic activity of sol–gel Ni-doped TiO2 on p-arsanilic acid degradation

Journal of Sol-Gel Science and Technology - Nickel-doped TiO2 (0.1, 0.5, 1.0, 2.5, 5.0, and 10.0 wt%) photocatalysts were prepared by the sol–gel method. Physicochemical properties were...     

Sol–gel synthesized vanadium doped TiO2 photocatalyst: physicochemical properties and visible light photocatalytic studies

Vanadium doped titanium dioxide (V–TiO₂) photocatalyst was synthesized by the sol–gel method using ammonium vanadate as vanadium source. The prepared samples were characterized by XRD, N₂ adsorption–desorption method, UV–Vis DRS, Fourier transform infrared (FTIR), scanning electron microscope–energy dispersive X-ray and photoluminescence (PL) analysis. The results show that V⁵⁺ ions were successfully incorporated into the crystal lattice of TiO₂ as a consequence, not only an obvious decrease in the band gap and a red shift of the absorption threshold into the visible light region was recorded for the V modified TiO₂, but, also a decrease in photogenerated electrons and holes recombination rate was observed as demonstrated by PL analysis. FTIR study indicated that in undoped TiO₂ sample the acetate group favored a bidentate bridging mode of binding with titanium atoms, whereas a bidentate chelating mode of linkage was observed in V–TiO₂ powders. The crystallite size of the samples calcined at 300 and 500 °C were decreased beyond the molar ratio of 200:1 (V:Ti), this may be due to dopant presence in the grain boundaries hindering the crystal growth. The photocatalytic activities for both pure and vanadium doped TiO₂ powders were tested in the discoloration of a reactive dyestuff, methylene blue, under visible light. The 100:1 (V:Ti) doped photocatalyst, calcined at 300 °C showed enhanced photocatalytic activity under visible light with a rate constant (k_obs) of 5.024 × 10^?3 min^?1 which is nearly five times higher than that of pure TiO₂, as result of low band gap value, high specific surface area and a decrease in recombination rate.     

Preparation of an Mo and C co-doped TiO2 catalyst by a calcination–hydrothermal method, and degradation of rhodamine B in visible light

Mo and C co-doped TiO₂ photocatalysts were successfully prepared by a calcination–hydrothermal method. The catalysts were characterized by XRD, XPS, DRS, FTIR, and Raman spectroscopy. Results from photocatalysis showed that 1%Mo–C4/TiO₂ had excellent visible light photocatalytic activity. This may be ascribed not only to the Mo and C doping but also to synergism between the Mo and C.     

Enhanced sunlight photocatalytic activity and recycled Ag–N co-doped TiO2 supported by expanded graphite C/C composites for degradation of organic pollutants

Research on Chemical Intermediates - Removing organic pollutants from wastewater is urgent for developing a sustainable ecological environment. A highly efficient visible light photocatalyst was...     

Characterization and photocatalytic activity of TiO2 by sol–gel in acid and basic environments

Journal of Sol-Gel Science and Technology - The sol–gel synthesis of water-based sols of nanocrystalline TiO2 in a large pH range (1.3–10.6) was carried out by acid hydrolysis of...     

Energy transfer or electron transfer?—DFT study on the mechanism of [2+2] cycloadditions induced by visible light photocatalysts

The intramolecular [2+2] cycloaddition of 1,3-dienes under visible light irradiation investigated by Yoon and his co-workers shows remarkably high yield and stereoselective differences under different photocatalysts. The reaction was speculated to be induced by energy transfer. However, the origin for these phenomena is still unclear. In this scene, the detailed mechanism for the [2+2] cycloaddition of 1,3-dienes under visible light has been investigated using density functional theory B3LYP and TPSSTPSS methods. The result shows that the reaction not only can be induced by energy transfer between photocatalysts and reactants, but also can be induced by electron transfer between them. The [2+2] cycloaddition induced by energy transfer is carried out along the potential energy surface (PES) of triplet excited states (T₁) firstly, and then goes back to the singlet ground state (S₀) via MECPs (minimum energy crossing points) between the PESs of the S₀ and T₁ states, forming the product in the S₀ state. The [2+2] reaction induced by electron transfer proceeds along the doublet state PES of the cation radical reactant and the neutral four-membered ring product could be obtained by electron transfer from the corresponding reactant or reduced photocatalyst. The origin of stereoselectivity of the [2+2] reaction is attributed to the reaction mechanism difference under different photocatalysts.     

Enhancing the photocatalytic activity of Ga2O3–TiO2 nanocomposites using sonication amplitudes for the degradation of Rhodamine B dye

A Ga₂O₃–TiO₂ photocatalyst was synthesized by a mechanomixing method followed by a sonication technique using different amplitudes of sonication (0%, 25%, 50%, and 75% of 20 kHz). The prepared photocatalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared, Brunauer–Emmett–Teller (BET) surface area (S_BET), zeta potential, and optical techniques. Ga₂O₃–TiO₂ exhibited an excellent photocatalytic activity for Rhodamine B (RhB) dye degradation under UV irradiation. The RhB degradation rate rose linearly with the increase of sonication amplitude. The photodegradation rate (k) of the synthesized samples was calculated according to the Langmuir–Hinshelwood kinetic expression. It reached a maximum of 5.25 × 10⁻² min⁻¹ with R² of 0.99 for Ga₂O₃–TiO₂ (75%) photocatalysts. The main reactive species were detected through radical scavenging experiments. The formation of hole reactive species is the rate-determining step in the case of Ga₂O₃–TiO₂ (75%) photocatalysts.     

Facile synthesis of thin black TiO2 − x nanosheets with enhanced lithium-storage capacity and visible light photocatalytic hydrogen production

Journal of Solid State Electrochemistry - In combination of a facile and scalable solvothermal method and solid-phase reduction reactions, a novel two-dimensional black TiO2 − x...     

Synthesis of Er3+:Y3Al5O12 and its effects on the solar light photocatalytic activity of TiO2–ZrO2 composite

The Er³⁺:Y₃Al₅O₁₂ as an upconversion luminescence agent, which can transform visible light into ultraviolet light, was synthesized by nitrate?Ccitrate acid and calcined method. Then, a novel photocatalyst, Er³⁺:Y₃Al₅O₁₂/TiO₂?CZrO₂, was prepared using ultrasonic dispersion and liquid boiling method. The samples were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). In succession, the degradation process of organic dye was monitored by UV?CVis spectrum and ion chromatography for verifying the photocatalytic activity of Er³⁺:Y₃Al₅O₁₂/TiO₂?CZrO₂. The influences on its photocatalytic activity such as Ti/Zr molar ratio, heat-treated temperature, and time were studied. In addition, the influences of initial concentration, Er³⁺:Y₃Al₅O₁₂/TiO₂?CZrO₂ amount, solar light irradiation time, and organic dye category on the photocatalytic degradation efficiency were also investigated. It was found the photocatalytic activity of Er³⁺:Y₃Al₅O₁₂/TiO₂?CZrO₂ was superior to Er³⁺:Y₃Al₅O₁₂/TiO₂ and Er³⁺:Y₃Al₅O₁₂/ZrO₂. Therefore, the Er³⁺:Y₃Al₅O₁₂/TiO₂?CZrO₂ is a useful photocatalytic material for the wastewater treatment duo to efficient utilization of solar light.     

Photocatalytic degradation pathway of sulfadiazine over Ag–TiO2 under visible light irradiation

Research on Chemical Intermediates - In the past decades, TiO2-based photocatalysis has received much research attention as an effective strategy for decomposing the antibiotics in a water system....     

Enzyme mediated synthesis of Ag–TiO2 photocatalyst for visible light degradation of reactive dye from aqueous solution

The purpose of this study was to develop bio-inspired photocatalyst with solar light activity for textile dye degradation. Three TiO₂ samples namely TiO₂ (TiO₂-A), biotemplated TiO₂ (TiO₂-B), and enzyme mediated Ag–TiO₂ biotemplate (TiO₂-C), were developed. The presence of anatase phase of TiO₂ and silver in synthesized samples were confirmed using X-ray diffraction, field emission scanning electron microscopy, energy-dispersive spectroscopy, and UV–Vis–NIR spectroscopy. Photocatalytic efficiencies of these photocatalysts were evaluated by studying the oxidation of a commercial reactive dye (reactive black) under solar light irradiation in batch reactors. Photocatalytic efficiencies of the sample were compared using statistical tools like one-way ANOVA and Tukey test. The results confirmed that photocatalytic efficiency of TiO₂-C was 40 % higher than that of TiO₂-A under solar light irradiation.     

Synthesis,characterization and investigation of photocatalytic activity of ZnFe2O4@MnO–GO and ZnFe2O4@MnO–rGO nanocomposites for degradation of dye Congo red from wastewater under visible light irradiation

Research on Chemical Intermediates - Magnetic ZnFe2O4@MnO–graphene oxide and ZnFe2O4@MnO–reduced graphene oxide nanocomposites were prepared via a facile co-precipitation and...     

Influence of calcination temperature on the photocatalytic property of Fe–Cu–ZnO/graphene under visible light irradiation

Fe–Cu–ZnO/graphene composites are prepared by sol-gel method. The influence of the calcination temperature on the catalytic performance of Fe–Cu–ZnO/graphene composites has been studied and their physicochemical properties are characterized via X-ray diffraction (XRD), fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), thermogravimetry-differential scanning calorimetry (TG-DSC) and UV-Vis diffuse reflectance spectra (UV–Vis–DRS). The results show that Fe–Cu–ZnO/graphene composite calcined at 400°C exhibits the highest photocatalytic activity and the degradation rate of dark green dye in aqueous medium achieves 99.28% under exposure of visible light irradiation. The zinc species in the catalyst calcined at 400°C are all converted to the hexagonal wurtzite structures, and Cu²⁺ and Fe³⁺ are substituted ions in Zn²⁺ sites or incorporated into interstitial sites in the ZnO lattice which broaden the spectral response range to visible light. Meanwhile, the electrical properties of graphene are excellent which contribute to the enhanced charge carrier separation, extended light absorption, and increased surface hydroxyl groups. In addition, the catalyst is found to be relatively high reusable.     

Preparation, characterization and photocatalytic properties of InVO4 nanopowder and InVO4–TiO2 nanocomposite toward degradation of azo dyes and formaldehyde under visible light and ultrasonic irradiation

In this study, photocatalytic activity of InVO₄ and InVO₄–TiO₂ nanoparticles in the degradation of aqueous solutions of industrial textile azo dyes such as Solophenyl Red 3BL, Coperoxon Nevy Blue RL and Black Nilusun 2BC (abbreviated as SR 3BL, CNB RL and BN 2BC, respectively) and also formaldehyde (abbreviated as FAD) under visible light and ultrasonic irradiations has been compared. The effect of various parameters such as pH, temperature, irradiation time, amounts of nanophotocatalyst and nanocomposite, and ultrasonic intensity on degradation rates was investigated. Then based on the Langmuir–Hinshelwood approach, reaction rates and adsorption equilibrium constants were calculated. The nanophotocatalyst and nanocomposite were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM) and UV‐Vis spectroscopic methods. It was observed that InVO₄–TiO₂ nanopowder was more reactive than pure InVO₄ in the degradation of azo dyes under both conditions of visible light and ultrasonic irradiations. It was noticeable that degradation percent was more under ultrasonic irradiation rather than under visible light irradiation.     

Visible light assisted photocatalytic degradation of organic dyes on TiO2–CNT nanocomposites

Journal of Sol-Gel Science and Technology - Carbon nanotubes (CNTs) uniformly decorated with nano-anatase TiO2 particles corresponding to different TiO2–CNT weight ratios (up to 90 %...