Effect of the status of Sm on the properties of Sm contained N doped TiO2 photocatalysts

Nitrogen-doped TiO₂ (TiO_2?xN_y) nanoparticles with and without adding Sm³⁺ were synthesized by thermohydrolysis of TiCl₃. The samples were characterized by X-ray diffraction, specific surface area determination, UV–Vis diffuse reflectance spectroscopy. The photocatalytic activity of the sample was investigated by employing the oxidative destruction of nitric oxide as a probe reaction using a flow reactor. Although the doping of Sm³⁺ in the lattice of titania was not useful to improve the photocatalytic activity, loading of samarium oxides on the surface of titania resulted in an improvement of the photocatalytic activity of the nitrogen-doped TiO₂. The beneficial effect was explained by an increased separation efficiency of the photogenerated electron–hole pairs.     

Low temperature operated highly sensitive,selective and stable NO2 gas sensors using N-doped SnO2-rGO nanohybrids

In this study, we report synthesis of SnO₂-rGO and N-doped SnO₂-rGO nanohybrids by facile hydrothermal method. The XRD analysis of the synthesized nanohybrids revealed a tetragonal rutile structure of SnO₂ lattice.Further structural, chemical, morphological and optical properties of SnO₂-rGO and SnO₂-NrGO nanohybrids were investigated by Raman, X-Ray Photoelectron spectroscopy, Transmission Electron Microscopy, UV–Vis spectroscopy and Photoluminescence spectroscopy. Furthermore, the gas sensing properties of the synthesized nanohybrids were studied in detail. It was observed that SR2 and SRN2 nanohybrids exhibited superior NO₂ sensing response (55.2 and 84.5% respectively) at low operating temperature (120 °C) and low gas concentration (0.5 ppm). Moreover, SR2 and SRN2 also exhibited excellent selectively towards NO₂ along with remarkable stability upto 90% over 30 days. This improved performance can be attributed to the synergetic effect of small particle size, high defect concentration and high surface area due to incorporation of SnO₂ along with N doping in rGO. Therefore, SR2 and SRN2 can be utilized as effective NO₂ gas sensors.     

Green synthesis of TiO2 nanospheres from isolated Aspergillus eucalypticola SLF1 and its multifunctionality in nanobioremediation of C. I. Reactive Blue 194 with antimicrobial and antioxidant activity

For synthesis of titanium dioxide (TiO₂) nanoparticles (NPs), Green methods have been proven to be more efficient than several physiochemical methods. This article presents a non-toxic, ecofriendly, cost-effective and a facile route of green synthesis of TiO₂ NPs by an isolated fungus Aspergillus eucalypticola SLF1, which exhibits excellent photocatalytic, antimicrobial and antioxidant activity without structural modification done by physicochemical methods. The TiO₂ NPs are characterized by UV–Visible spectroscopy, XRD, FTIR, FE-SEM, DLS, TEM, BET, Raman spectroscopy and PL. The mesoporous, anatase phase, with a band gap 3.49 eV observed by BET, XRD. UV–Visible spectral analysis displayed sunlight driven photocatalytic performance against C. I. Reactive Blue 194 by advanced oxidation process. Decolourization and 99.70% degradation within 30 min exhibited pseudo first order kinetic with reaction rate constant 0.1935 min⁻¹ by linear method. These findings are superior physicochemical methods. Ecofriendly degradation was confirmed by UV–Vis. HPLC and LCMS etc and phytotoxic studies.     

Synthesis,characterization, photocatalytic and antibacterial properties of copper Ferrite/MXene (CuFe2O4/Ti3C2) nanohybrids

The synthesis of CuFe₂O₄/MXene nanohybrids was carried out via an ultrasonication approach. The prepared composite material exhibited an outstanding photocatalytic performance and antibacterial activity compared to individual CuFe₂O₄ (CF) and MXene. The CF nanonuts (Nns) assisted the reduced aggregation of MXene layers. The structural and morphological analysis of the presented nanohybrids were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR), Electrochemical impedance spectroscopy (EIS), and ultraviolet (UV)-visible spectroscopy. The obtained sheet-to-sheet linkage provided an opportunity for the degradation of organic dyes. The photocatalyst CF/MXene nanohybrids exhibited 4.5-fold higher photocatalytic activity than pristine CF. The mechanism of degradation of methylene blue dye by CF/MXene was explained through kinetic studies. This work will offer significant scientific contributions to researchers working on water desalination.     

Synthesis,analysis and characterization of ordered mesoporous TiO2/SBA-15 matrix: Effect of calcination temperature

Mesoporous TiO₂/SBA-15 matrix was prepared by the sol–gel synthesis of TiO₂ in previously prepared SBA-15 particles. Nonionic surfactant was used as liquid template and Na₂SiO₄ as SiO₂ precursor for the synthesis of mesoporous silica SBA-15 with high specific surface area. Different calcination temperature was used for the synthesis and analysis of TiO₂/SBA-15 matrix. The synthesized titania/silica composites were characterized by X-ray diffraction, FTIR, TEM, UV–vis spectroscopy, etc. TEM micrographs showed titania is successfully embedded in SBA-15 channel. Different calcination temperature indicates different size of particle formation and different photocatalytic properties. The activity test indicated that TiO₂/SBA-15 composite prepared by this method had better photocatalytic performance than pure TiO₂. The preparation method and the textural characteristics of mesoporous materials have great influence for the photocatalytic activity.     

Photocatalytic activity of titania modified mesoporous silica for pollution control

A series of titania modified mesoporous silicates with variable Si/Ti ratios were prepared using titanium tetrabutoxide by impregnation method. The samples were characterized by different analytical techniques such as XRD, TEM, FT-IR, low temperature N₂ sorption, and UV–Vis diffused reflectance spectroscopy. The TiO₂ supported on mesoporous silica was found to be in the anatase form. Crystallite size calculated using Scherrer’s formula was found to be in the range 18–20 nm. However, the TiO₂ particle diameter estimated by TEM was 5 nm. UV–Vis spectra showed a blue-shift of the absorption edge for all the samples. The BET surface area decreased with TiO₂ loading. Photodegradation of basic dye-like methylene blue (MB) was studied on these titania modified mesoporous silica using UV irradiation. Volatile organic pollutants like phenol and toluene can also be photocatalytically degraded using these titania modified mesoporous silicates.     

Green synthesis of Ni@Fe3O4 and CuO nanoparticles using Euphorbia maculata extract as photocatalysts for the degradation of organic pollutants under UV-irradiation

This paper presents a fast, biogenic and green method for the synthesis of highly stable and small sized metal nanoparticles (MNPs). This technique has some benefits compared to the conventional physical and chemical methods. It is simple, rapid, cheap and environmentally friendly. In addition, it does not require any costly or hazardous chemicals. The extracts of Euphorbia maculata aerial parts were used in a green synthesis method in order to prepare magnetic Ni@Fe₃O₄ and CuO NPs. Fourier transforms infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), ultraviolet–visible (UV–Vis), energy dispersive X-ray spectrometry (EDS), Brunauer-Emmett-Teller (BET) and thermo gravimetric-differential thermal analysis (TGA) analytical techniques were used for analyzing the green synthesized compounds. The photocatalytic activity of the synthesized NPs was tested in the degradation of different organic dye pollutants such as congo red (CR), methylene blue (MB) and Rhodamine B (RhB) under UV irradiation. The effects of different parameters such as nanoparticle dosage, contact time, pH, and initial dye concentrations on the capacity of the photocatalyst adsorption were also studied. The comparison of the photocatalytic activity of the biosynthesized nanoparticles reveals that the catalytic activity of CuO NPs is higher than that of Ni@Fe₃O₄ NPs. Furthermore, good photocatalytic stability of the NPs in the degradation of MB under UV light irradiation was observed after the recycling. The photocatalyst efficiency did not considerably change after four cycles, which indicated excellent photocatalytic stability.     

Solvothermal synthesis and characterizations of graphene-ZnBi12O20 nanocomposites for visible-light driven photocatalytic applications

The Bismuth based Zinc metal oxide (ZnBi₁₂O₂₀) nanorods were synthesized via single step solvothermal approach. The characterization of synthesized hybridized structure was done by several analysis such as X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (UVvis–DRS), Fourier transform-infrared spectroscopy (FT–IR), Thermogravimetric analysis (TGA), Raman spectroscopy, Field-Emission scanning electron microscopy (FESEM), Energy dispersive analysis of X-rays (EDX), High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy. The photocatalytic activity of ZnBi₁₂O₂₀ and an incorporation of varying weight percentages of GO (1–4 wt %) into ZnBi₁₂O₂₀ catalyst (GZBC) were analyzed under visible light irradiation by the degradation of an aqueous solution of Methylene blue (MB) and Methyl orange (MO) dye. Among various developed nanocomposites, 3 wt% GZBC reduced graphene oxide exfoliated nanocomposites has revealed the degradation efficiency as 96.04, 94.52% at 100 and 120 min for MB and MO respectively with enriched visible light absorption range. The photocatalytic property of 3 wt % reduced graphene oxide exhibits higher degradation behavior than that of other synthesized nano-composites.     

Synthesis of carbon nanotube (CNT)‐BiFeO3 and (CNT)‐Bi2Fe4O9 nanocomposites and its enhanced photocatalytic properties

Pure and carbon nanotube (CNT) attached BiFeO₃ and Bi₂Fe₄O₉ were prepared via hydrothermal route at fixed temperature, with time and mineralizer as variants. Phase purity of products was determined through X‐ray diffraction (XRD) studies. FESEM analyses revealed that synthesized materials exhibited various morphologies, depending on the mineralizer being employed in the synthesis. Optical band gap measurements have been carried out using UV‐Vis spectroscopy analyses. The attachment of CNT reduces the bandgap, and consequently enhances photocatalytic activity due to the electron transfer from BiFeO₃ to CNT. The pseudo‐first order model of reaction kinetics has been used successfully to study the associated mechanism.     

Photocatalytic Activity of Degussa P25 TiO2/Au Obtained Using Argon (Ar) and Nitrogen (N2) Plasma

Titania Degussa P25 powder was treated with Argon (Ar) and Nitrogen (N₂) gas plasma inside of a closed homemade chamber system at 50 Pa of pressure. The electric discharge was generated applying an AC voltage (0–15,000 V) to a pair of aluminum electrodes. Two sets of samples were analyzed. In the first one, the plasma is applied directly on a layer of titania P25 that is spread out on top of one of the electrodes and, in the second one, a gold foil substrate is positioned between the titania powder and the electrode, named TiO₂/Au. In the last sample, gold coated titania nanoparticles or clusters of gold are formed, changing the optical properties of the material. The evolution of the optical properties of the obtained samples was analized using UV–Vis diffuse reflectance. The spectra show a shift in the band gap and a broad band in P25/Au associated with the gold plasmonic band. Additionally, the photocatalytic activity was evaluated by monitoring the photodegradation of methylene blue solution (0.01 g/L), using UV–Vis absorption analysis in the range 250–850 nm. After the plasma is applied, the gold impregnation over the titania surface increases the photocatalytic activity.     

Chemical synthesis and characterization of some conducting polyaniline derivatives: Investigation of the effect of protonation medium

Poly(o‐toluidine) (POT) and poly(2‐chloroaniline) (P2ClAn) emeraldine salts were synthesized chemically by using formic (HCOOH), acetic (CH₃COOH), propionic (C₂H₅COOH), and boric (H₃BO₃) acids. Ultraviolet‐visible absorption spectra (UV–Vis) analysis results indicated that POT has the better protonation effects than P2ClAn. Among the POTs synthesized using the four different acids, POT(H₃BO₃) showed the least protonation effect. The conductivities of prepared polymers were measured by a four‐probe technique. The highest conductivities were obtained in POTs synthesized by using formic, acetic, and propionic acids. Magnetic susceptibility measurements of the polymer salts were analyzed by using Gouy scale and it was found that POT(CH₃COOH) and POT(C₂H₅COOH) salts are of bipolaron structure; other polymer salts are of polaron structure. The characterization of the polymers were investigated by Fourier infrared spectroscopy (FTIR), UV–Vis, thermogravimetric analysis, and scanning electron microscopy. It was observed from UV–Vis spectra of the emeraldine salt of POT that wavelengths belonging to π → π* transitions shifted to shorter wavelengths with increasing pKa values of acids. POT and P2ClAn synthesized in four different protonation media decomposed with three‐step and three‐ or two‐step weight loss, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1993–2000, 2002; DOI 10.1002/app.10487     

A Simple Method for Synthesis of S-Doped TiO2 of High Photocatalytic Activity

S-doped TiO₂ samples were synthesized by use of thiourea. The elemental analysis was confirmed by X-ray fluorescence, the phases were identified by X-ray diffraction and further characterization was carried out by surface area measurement and UV–Vis spectroscopy. The photocatalytic activity was measured by exposing methylene blue to sunlight in the presence of TiO₂. It was observed that the S-doped anatase phase showed high photocatalytic activity in comparison to other samples.     

Fly ash supported photocatalytic nanocomposite poly(3,4‐ethylenedioxythiophene)/TiO2 for azo dye removal under simulated solar irradiation

The main objective of this study was to develop a supported photocatalyst for wastewater treatment with extended efficiency under solar light. For that purpose titanium dioxide (TiO₂) was immobilized by sol–gel synthesis on the surface of the waste fly ash (FA). On such prepared composite material, conductive polymer poly(3,4‐ethylenedioxythiophene) was grafted by in situ chemical oxidative polymerization with different oxidants, ammonium persulfate (APS), and iron(III) chloride, FeCl₃. Characterization was performed by Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction, thermogravimetric analysis, and gas sorption analysis. Photocatalytic activity of composite photocatalyst was evaluated by testing removal efficiency of C.I. Reactive Red 45 (RR45) azo dye in three consecutive photocatalytic cycles under different pH. Discoloration of RR45 was measured using UV/Vis spectroscopy. It was determined that oxidant type plays major role in structure of composite as sample synthesized with APS had higher fraction of polymer and largest pore volume. The same composite had much better photocatalytic efficiency than sample synthesized with FeCl₃ oxidant. It was also determined that there is a very strong adsorption of dye molecules on the surface of photocatalyst that quickly causes saturation of photocatalyst and efficiency drop after first cycle. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46316.     

The comparative study of photocatalytic self‐cleaning properties of synthesized nanoscale titania and zirconia onto polyacrylonitrile fibers

The photocatalytic activity of TiO₂ and ZrO₂‐coated polyacrylonitrile (PAN) fibers was compared through the self‐cleaning of methylene blue and eosin yellowish. TiO₂ and ZrO₂ nanocrystals were successfully synthesized and deposited onto PAN fibers with photocatalytic self‐cleaning activity using the sol‐gel process at low temperature. The pristine and treated samples have been characterized by several techniques, such as scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, diffuse reflectance spectroscopy, X‐ray diffraction, and thermogravimetric analysis. The TiO₂ nanoparticles with 10–20 nm in size, and ZrO₂ with 20–40 nm have been synthesized to form dispersed particles on the fiber surface, which shows photocatalytic properties when exposed to UV–Vis light. The photocatalytic activity, tested by measuring the degradation of adsorbed methylene blue and Eosin Y. Photocatalytic activity of TiO₂‐coated fibers toward dyes degradation was higher than that of ZrO₂‐coated fibers. This preparation technique can be also applied to new fabrics to create self‐cleaning and UV irradiation protection properties in them. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Optical and Structure Properties of Nanocrystalline Titania Powders with Cu Dopant

TiO₂ nanopowders doped by Cu were prepared by the sol–gel method. The effects of Cu doping on the structural, optical, and photo-catalytic properties of titania nanopowders have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV–Vis absorption spectroscopy. XRD results suggest that adding impurities has a significant effect on anatase phase stability, crystallinity, and particle size of TiO₂. Titania rutile phase formation in the system (Ti–Cu) was promoted by Cu²⁺ doped TiO₂. The photo-catalytic activity was evaluated by photo-catalytic degradation kinetics of aqueous methylene orange (MO) under visible radiation. The results show that the photo-catalytic activity of the 5 %Cu doped TiO₂ nanopowders has a larger degradation efficiency than pure TiO ₂ under visible light. Also, the minimum band gap was estimated to be ～ 1.9–2 eV from UV–Vis spectra.     

Preparation of Ag nanoparticles loaded TiO2 nanoplate arrays on activated carbon fibers with enhanced photocatalytic activity

Ag loaded TiO₂ nanoplate array which grew on activated carbon fiber (ACF) was prepared in the present work. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–Vis diffuse reflectance spectra (DRS). The photocatalytic degradation of methylene blue (MB) was used to investigate the activity of the synthesized samples. Under both UV and visible light irradiation, the Ag loaded samples showed enhanced photocatalytic activity. Besides, the effect of the deposition dosage of Ag nanoparticles on the photocatalytic activity was also investigated. Under UV light irradiation, the Ag nanoparticles acted as electron traps, which enhanced electron–hole separation efficiency of TiO₂. Under visible light irradiation, the Ag nanoparticles showed surface plasmon resonance, which induced the visible light responsive photocatalytic activity for the obtained samples.     

Synthesis of 2D material based Bi2O3/MXene nanohybrids and their applications for the removal of industrial effluents

2D material-based Bi₂O₃/MXene nanohybrids were successfully fabricated through an ultrasonication method. MXene (Ti₃C₂Tx) nanosheets were prepared via simple H.F. etching while bismuth oxide nanoflowers were prepared by the co-precipitation method. The structure, morphologies, and optical properties of all the prepared samples were analyzed by various advance techniques such as X-ray diffraction (XRD), UV–Visible spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). To check the photocatalytic efficiency of prepared material was performed for both colored and colorless dyes. A significant increase in photocatalytic properties were observed for methylene blue and benzoic acid. The prepared nanohybrid showed 1.6 folds higher efficiency than bismuth oxide nanopetals. The relatively higher utilization e?ciency of sunlight and the rapid separation rate of photogenerated electron and hole pairs helped to enhance the photocatalytic performance synergistically. Additionally, the antibacterial activity of all samples was also carried out using the disc diffusion method against K. pneumonia and S. aureus. Improved properties could be attributed to an increase in d-spacing of 2D MXene layers by inserting nanopetals which reduced the restacking of MXene layers. Furthermore, multiple functional groups on the surface of MXene will also play an important role in enhancing the properties of its nanohybrids. We expect that the as-synthesized nanohybrid will attract researchers’ attentions for the degradation of industrial pollutants.     

How different dopants leads to difference in photocatalytic activity in doped TiO2?

This study explores the significance of dopant location in a doped TiO₂ nanostructure in ascertaining its photocatalytic properties. The un-doped TiO₂, boron-doped TiO₂ (B–TiO₂) and nitrogen-doped TiO₂ (N–TiO₂) photocatalysts were synthesized (with variable dopant concentrations) via sol-gel method. The photocatalysts were further characterized for structural, surface, and physico-chemical properties in reference to their influence on photocatalytic properties. The results of X-ray diffraction (XRD), micro Raman, Energy dispersive X-ray technique (EDX), X-ray photoelectron spectroscopy (XPS), and Fourier Transform infrared spectroscopy (FTIR) confirmed the existence of B and N atoms in the TiO₂ crystal lattice. The results also indicated that the B and N doping promoted the formation of rutile phase in doped TiO₂. Further, B doping leads to decrease in the surface area whereas N doping leads to increase in surface area of TiO₂. The UV–Vis DRS analysis revealed that a red shift in absorption band edge occurs upon B and N doping. The band gap values also decreased to 2.96 and 2.27 eV in B–TiO₂ and N–TiO₂, respectively in comparison to 2.98 for un-doped TiO₂. The photocatalytic degradation studies of diclofenac sodium (DCLF) were conducted to examine the effect of dopant role on the efficiency of doped photocatalyst. B–TiO₂ exhibited maximum photocatalytic activity by degrading 98% of DCLF in comparison to N–TiO₂, which showed 95% degradation.     

Influence of pH on the morphology and photocatalytic activity of CuO obtained by the sonochemical method using different surfactants

In this work, copper oxide II (CuO) was obtained using different surfactants (PVP, PEG and EDA), as well as without surfactant (WS), varying synthesis pH (8, 11 and 13). The powders were characterized by X-ray diffraction (XRD), field scanning electron microscopy (SEM), Brunauer-Emmett-Teller method (BET), UV–Visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), photoluminescent properties and their photocatalytic properties were measured against the methylene blue dye under UV radiation. XRD patterns showed that a pH increase from 8 to 13 favors CuO single phase formation, whereas Cu₂(OH)₃(NO₃) secondary peaks appear at lower values. FTIR spectra confirmed the appearance of Cu₂(OH)₃(NO₃) through the vibrations related to the hydroxide nitrate. The SEM images showed the variations in morphology obtained through the different surfactants and the medium pH, in which, the morphology presents a leaf appearance with a lower value (pH =?8), while increasing the pH to 13, changed the morphology into agglomerate flower-like nanoparticles. The BET results showed that the samples obtained without surfactant and with PEG at pH =?8 had the highest and lowest surface area, being 18.935 and 4.531?m² g^?1, respectively. The photocatalytic activity shows that the CuO powders that have a small amount of Cu₂(OH)₃(NO₃) present better methylene blue dye degradability when illuminated by UV–Vis radiation.     

Hydrothermal synthesis of graphene wrapped Fe-doped TiO2 nanospheres with high photocatalysis performance

In this study, graphene wrapped Fe-doped TiO₂ (G-TiO₂-Fe) spheres were prepared through a simple hydrothermal process. The structural, optical and photocatalytic properties of synthesized composite were characterized by field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), Raman Microprobe (Raman), X-ray photoelectron spectroscopy (XPS) and UV–Vis diffuse reflectance spectrophotometer (DRS). The G-TiO₂-Fe composite showed a significant red-shift in light response edge as compared with TiO₂. Meanwhile, the band gap exhibited an obvious decline from 3.24 to 2.99 eV. The photocatalytic capacity of G-TiO₂-Fe was further evaluated by methylene blue (MB) degradation experiments, and the results indicated that the optimized G-TiO₂-Fe exhibited a remarkable increase in photocatalytic activity. The superior photocatalytic performance of the novel material could be ascribed to the synthetic effects of doped Fe and wrapped graphene shells. The unique geometrical configuration and constructive component which modified the TiO₂ electronic structure will largely improve the electron transporting efficiency and restrain the electron-hole recombination.