Activity For Degradation Of Methyl Orange Research Articles

Efficient visible-light photocatalytic performance of cuprous oxide porous nanosheet arrays

One-dimensional nanostructures are of great interest for a wide range of applications. In this work, we demonstrated the fabrication of visible-light-responsive Cu2O porous nanosheet arrays. The synthesis involved the growth of Cu(OH)2 nanosheet arrays on Cu mesh by solution-based corrosion and thermal transformation of Cu(OH)2 nanosheet to Cu2O porous nanosheets on Cu mesh. Benefiting from the one dimensional array structure and porous structure, the as-prepared Cu2O porous nanosheet arrays exhibited significantly improved photocatalytic activity for methyl orange degradation under visible light irradiation.

Structure, morphology and photocatalytic activity of attapulgite/Ag3PO4 hybrids synthesized by a facile chemical precipitation route

Attapulgite (ATP)/Ag3PO4 hybrids have been synthesized via a facile chemical precipitation route, and we also examined the effect of precursor phosphate types on the structure, morphology and photocatalytic property of the obtained products. It was found that the ATP surfaces were uniformly coated by ultrathin Ag3PO4 nanoparticles (NPs) with sizes of 5–20 nm, while the as-synthesized hybrids exhibited the higher photocatalytic activities for methyl orange degradation than the single Ag3PO4 crystals although the amount of active species were decreased a lot. The behavior was thus attributed to both the smaller particle sizes and the larger surface. In addition, it was also observed that the photocatalytic activities of those hybrids were dependent on the types of phosphate salts. In details, a few impurities were found in the samples synthesized via Na3PO4, while the ones synthesized using two other phosphates (Na2HPO4, NaH2PO4) exhibited the higher photocatalytic activities and stabilities due to the higher loading amount, smaller size and more uniform coating of Ag3PO4 NPs. This work presents a new approach for expanding the possibilities for developing low cost and visible-light responsive photocatalysts.

Cosolvent-free nanocasting synthesis of ordered mesoporous g-C3N4 and its remarkable photocatalytic activity for methyl orange degradation

Ordered mesoporous g-C3N4, synthesized via a green cosolvent-free nanocasting route, exhibited remarkable photodegradation performance towards methyl orange with a degradation rate constant 30 times higher than that of bulk g-C3N4.

Synthesis, characterization and photocatalytic activity of cubic-like CuCr2O4 for dye degradation under visible light irradiation

CuCr2O4 nanoparticles with cubic-like morphology were prepared via hydrothermal synthesis method without template. The CuCr2O4 samples were characterized by thermogravimetry and differential scanning calorimetry (TG–DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra (DRS) and Zeta potentials, respectively. The results indicated that cubic-like CuCr2O4 could be successfully synthesized by calcining the precursor at 600°C, and the calcination temperature greatly influenced the morphology and optical performance of CuCr2O4. The pH at the point of zero charge (pHpzc) of the CuCr2O4 calcined at 600°C was about 4.52. The photocatalytic activity of CuCr2O4 was evaluated for degradation of rhodamine B (RhB), methylene blue (MB), and methyl orange (MO) in the presence of H2O2 under visible light irradiation and the effects of the calcination temperature, dosage of photocatalyst, etc., on photocatalytic activity were studied in detail. The photocatalytic results revealed that the CuCr2O4 photocatalyst was of high activity for degradation of RhB (96.8%) and MB (99.5%), but very low activity for degradation of MO (14%). The CuCr2O4 sample calcined at 600°C possesses the best photocatalytic activity, and the optimal dosage of the CuCr2O4 photocatalyst is 0.4g/L.

Facile synthesis of Ag-ZnO hybrid nanospindles for highly efficient photocatalytic degradation of methyl orange.

Highly photocatalytically active Ag nanoparticle decorated ZnO nanospindles were synthesized by a facile wet chemical method. The structural and optical properties of the as-synthesized materials were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and high resolution TEM (HRTEM) with energy dispersive X-ray spectroscopy, UV-visible absorption spectroscopy and Raman spectroscopy. The photocatalytic activity of these nanostructures was evaluated by analyzing sunlight driven degradation of methyl orange (MO) dye and it was observed that Ag nanoparticle modified ZnO nanospindles show significantly enhanced photocatalytic activity for degradation of MO, as compared to ZnO nanospindles. We attribute the observed enhanced photocatalytic activity of Ag nanoparticle decorated ZnO nanospindles to their improved sunlight utilization efficiency and the efficient suppression of recombination of photogenerated charge carriers due to the electron scavenging action of Ag nanoparticles and the interfacial electron transfers due to the Schottky junction between Ag nanoparticles and ZnO nanospindles.

AgI/TiO2 nanocomposites: Ultrasound-assisted preparation, visible-light induced photocatalytic degradation of methyl orange and antibacterial activity

AgI/TiO2 nanocomposites were prepared by an ultrasound-assisted precipitation process and subsequent low-temperature (350°C) calcination. The crystal phase, morphology and optical properties of the AgI/TiO2 nanocomposites were characterized by X-ray diffraction, transmission electron microscopy and UV–vis absorption spectroscopy. After calcination, the crystallite size of AgI nanoparticles in the AgI/TiO2 nanocomposites decreased, and visible light absorption intensity of the AgI/TiO2 nanocomposites was significantly enhanced. The AgI/TiO2 nanocomposites after calcination exhibited the superior photocatalytic activity for methyl orange degradation and killing of Escherichia coli under visible light irradiation. The improvement of photocatalytic activity could be attributed to two reasons, namely, reduced crystallite size and enhanced visible light absorption of AgI nanoparticles in calcined AgI/TiO2 nanocomposites. The trapping experiments demonstrated that superoxide radical (O2−) and holes (h+) were the main reactive species for the photodegradation of methyl orange under visible light irradiation. The ultrasound-assisted preparation approach is efficient and facile, which promotes large-scale production and application of AgI/TiO2 nanocomposites in photocatalytic degradation of organic pollutants, disinfection and other fields.

Visible light responsive sulfated rare earth doped TiO2@fumed SiO2 composites with mesoporosity: Enhanced photocatalytic activity for methyl orange degradation

Visible light (VL) responsive mesoporous sulfated rare earth ions (Nd3+, La3+, Y3+) incorporated TiO2@fumed SiO2 photocatalysts were prepared by sol–gel method with P123 (EO20PO70EO20) as a template. The resultant samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption–desorption measurements (BET), UV–vis diffuse reflectance spectroscopy, photoluminescence (PL) spectra, Fourier transform infrared spectroscopy (FTIR) and thermal analyses (TG-DTA). In comparison with nondoped sample, RE-doped samples showed not only an increase in the surface areas and pore volumes, but also an inhibition of titania phase transition from anatase to rutile. Photo-degradation results revealed that RE-doped samples could greatly improve the photocatalytic activity, and the experimental degradation rates of methyl orange (MO) were higher than that catalyzed by undoped samples and Degussa P-25, obeyed the order of Nd3+>La3+>Y3+. Nd-doped sample expressed the highest photoactivity and the optimal dosage was 0.25mol%, which resulted in MO degradation rates of 99.8% and 90.05% irradiation under UV for 60min and VL (λ>400nm) for 40h, respectively. The enhanced photocatalytic activity could be attributed to the higher specific area, good crystallinity, strong VL absorption and effective separation of photogenerated electron–hole pairs in the catalyst.

Effect of Ce, N and S multi-doping on the photocatalytic activity of TiO2

A visible light active photocatalyst was synthesized by multiple doping of TiO2 with Ce, N and S. The multidoped catalyst showed higher photocatalytic activity for methyl orange degradation from aqueous solution compared to P25 and undoped TiO2. The photocatalytic activity decreased in the order Ce0.6NS–TiO2>P25>NS–TiO2>Ce0.6–TiO2>TiO2. TiO2 and doped TiO2 existed as anatase phase with average particle size of 10nm. In the multidoped TiO2, N substituted for O whereas S substituted for Ti. UV–vis absorption spectra showed an increased visible light absorption for doped TiO2 compared to the undoped one. An increased fluorescence lifetime for the charge carriers was observed for the doped samples as compared to undoped TiO2. The enhanced photocatalytic activity of Ce0.6NS–TiO2 is attributed to a synergistic effect of the dopants in increasing the visible light absorption and lifetime of the photogenerated charge carriers.

Reduced graphene oxide modified Ag/AgBr with enhanced visible light photocatalytic activity for methyl orange degradation

A novel visible light driven photocatalyst, reduced graphene oxide (RGO)-modified Ag/AgBr (Ag/AgBr/RGO), was synthesized by sequent double-jet precipitation, hydrothermal, and UV light reduction processes. The XPS and Raman results confirmed that part of GO was successfully reduced by hydrothermal treatment. Compared with Ag/AgBr, Ag/AgBr/RGO exhibited higher visible light photocatalytic activity for the degradation of methyl orange. The EIS analysis revealed that Ag/AgBr/RGO has better capability for charge transfer than Ag/AgBr. The excellent photocatalytic activity of Ag/AgBr/RGO is attributed to the strong visible light absorption of Ag nanoparticles and AgBr as well as the effective separation of photogenerated electrons and holes.

Silver halide/silver iodide@silver composite with excellent visible light photocatalytic activity for methyl orange degradation

AgBr/AgI@Ag composite photocatalyst was prepared by a handy multistep route, including controllable double-jet precipitation to synthesize cubic AgBr microcrystals, ion exchange to form AgI on AgBr surface, and visible light reduction to generate Ag nanoparticles. UV–Vis diffuse reflectance and electrochemical impedance spectra demonstrated that AgBr/AgI composite structure not only favors forming more silver nanoparticles to harvest visible light but also facilitates the transfer of charge carriers when compared with pure AgBr. Beneficial from the synergistic effect of highly effective visible light harvest and electron–hole separation, AgBr/AgI@Ag shows higher photocatalytic activity for the degradation of methyl orange (MO) than AgBr, AgBr@Ag, and AgBr/AgBr.

Low-temperature synthesis of anatase C-N-TiO2 photocatalyst with enhanced visible-light-induced photocatalytic activity

Visible-light-activated C-N-TiO2 powders were synthesized by a facile peptization-reflux method at 120°C. The physical and photophysical properties of the photocatalyst have been characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and UV–vis diffuse reflectance spectra. The as-prepared C-N-TiO2 possessed a diameter of ca. 7nm with anatase crystalline structure, and showed a shift of the absorption edge to a lower energy and a stronger absorption in the visible region. XPS results indicated that the retained alkoxyl groups existed on the surface of TiO2 and the doped nitrogen incorporated in the TiO2 as formation of N-Ti-O and Ti-O-N. And C-N-TiO2 samples had excellent photocatalytic activity for methyl orange degradation under visible light irradiation, which could be assigned to synergistic effect between the retained alkoxyls and the nitrogen doping.

Preparation and Properties of Eu<sup>3+</sup>-Doped TiO<sub>2</sub> Nanowires

Nanowires of sodium titanate, TiO2 and Eu3+/TiO2 were synthesized by hydrothermal method, and their microstructure, optical properties and valence states of exterior elements were characterized by X-ray powder diffraction (XRD), scanning electron microscopy(SEM), X-ray photoelectron spectroscopy (XPS) and UV-Vis diffuse reflectance spectroscopy techniques. At the same time, the photocatalytic activities of the materials for degradation of methyl orange under visible-light irradiation were also investigated. The results showed the formation of nanowires of sodium titanate with average crystallite sizes of 50-200 nm and in lengths from several microns to several dozens microns, and its chemical formula was determined to be Na2Ti3O7. TiO2 and Eu3+ /TiO2nanowires were prepared from the Na2Ti3O7 nanowires via ion exchange (i.e., with H+ and Eu3+ ions) and high temperature sintering processes. These three kinds of nanowires showed different photocatalytic activities for degradation of methyl orange. Na2Ti3O7 nanowire did not show any photocatalytic activity for methyl orange degradation, while TiO2 nanowire was superior to Na2Ti3O7 nanowire; and, Eu3+/ TiO2 nanowire possessed the highest photocatalytic activity.

Room-Temperature Synthesis of Self-Assembled Sb2S3 Films and Nanorings via a Two-Phase Approach

The freestanding Sb(2)S(3) films were easily synthesized at the interface of water and toluene at room temperature, where Na(2)S and (C(2)H(5)OCS(2))(3)Sb (xanthate, O-ethyldithiocarbonate) acted as sulfur and antimony source, respectively. After 3 h of aging, the Sb(2)S(3) films with a flat surface toward organic side and rough surface toward aqueous side were assembled by sheaflike Sb(2)S(3) nanowires. The Sb(2)S(3) nanorings formed by end-to-end connection of the bundled nanowires appeared in the water layer when the reaction time reached 24 h. The Sb(2)S(3) nanorings showed higher photocatalytic activity for methyl orange degradation under visible light than the Sb(2)S(3) films owing to broader spectrum response and better aqueous dispersion.

Large scale electrochemical synthesis of high quality carbon nanodots and their photocatalytic property

High quality carbon nanodots (C-dots) with high purity were synthesized through a mild, one-step electrochemical approach, without the assistance of any chemicals but only pure water. This high productivity method makes the synthetic process of C-dots synthesis both economical as well as environment-friendly. The as prepared C-dots are predominantly multi-layer graphene oxide, with luminescence and high up-conversion photoluminescence (emission of light at shorter wavelengths than the excitation wavelength). Meanwhile, C-dots showed peroxidise mimetic function and visible-light-sensitive photocatalytic activity for methyl orange degradation. In addition, a novel photocatalyst (TiO(2)/C-dots) was obtained by combining C-dots with TiO(2) through an easy hydrothermal method. Remarkably, TiO(2)/C-dots exhibited an excellent visible-light photocatalytic activity.

Effect of Co-Doping of Nano Silver, Carbon and Nitrogen on Titania on the Visible Light Activity for Methylorange Degradation

Co-doping of nanosilver, carbon and nitrogen is done on titania to get improved photodegradation of pollutants when compared to single doping. Anion doping extends the absorption of TiO2 to the visible region; whereas noble metal NP doping prevents the recombination of photoinduced electrons and holes. Doped TiO2 prepared using sol gel method allows efficient dispersion of nano silver and thus enhances the photodegradability. X-ray Diffraction analysis shows the efficient dispersion of incorporated nano silver over anatase TiO2. The visible light absorption is confirmed from UV-Vis Diffuse Reflectance spectral studies. Photocatalytic activity is investigated by the degradation of methyl orange as a model pollutant. Efficient degradation in visible light shows the synergetic effect of carbon and nitrogen doping as well as nano silver loading on the performance of TiO2.

Preparation, characterization of Y 3+-doped TiO 2 nanoparticles and their photocatalytic activities for methyl orange degradation

A series of pure and Y 3+-doped TiO 2 nanoparticles with high photocatalytic activities were prepared by a sol-gel method using tetra-n-butyl titanate as precursor. The as-prepared catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and diffuse reflectance spectroscopy (DRS). The results indicated that yttrium doping could effectively reduce the crystalline size, inhibit the anatase-to-rutile phase transformation and surppress the recombination of the photogenerated electron-hole pairs. The DRS results showed that the optical absorption edge shifted to red direction owing to yttrium ion doping. The photocatalytic activities of samples were evaluated by the photodegradation of methyl orange (MO) aqueous solution under 300 W high pressure mercury lamp irradiation. Photodegradation results revealed that Y 3+ doping could greatly improve the photocatalytic activity of TiO 2. In this experiment, the optimal dosage was 1.5 mol.% when samples were calcined at 773 K for 2 h, which caused a MO photodegradation rate of 99.8% under UV irradiation for 70 min.

Preparation, electrocatalytic and photocatalytic performances of nanoscaled CuO/Co3O4 composite oxides

Cu-Co composite oxides with different Cu/Co atomic ratios were prepared by the calcination of the precursors synthesized via a co-precipitation method. The samples were characterized by XRD, SEM and TEM, respectively. The XRD analysis revealed that only spinel structure of Cu-Co composite oxide was confirmed with lower Cu/Co ratio (<1:2). The sizes and morphologies of samples are controlled significantly by the Cu/Co atomic ratios. The electrocatalytic activity for p-nitrophenol reduction in a basic solution with the samples decorated on glassy carbon (GC) electrodes was tested by cyclic voltammetry (CV). The results showed that the sample with Cu/Co ratio of 2:8 exhibited the highest catalytic activity for p-nitrophenol reduction. The photocatalytic performances of the samples for the degradation of methyl orange under irradiation of visible light were investigated. The samples with Cu/Co ratios from 5:5 to 10:0 all showed better photocatalytic activities for methyl orange degradation, but the sample with Cu/Co ratio of 9:1 exhibited much higher catalytic activity. The catalyst with Cu/Co ratio of 9:1 also exhibited excellent repeatability for the catalytic degradation of methyl orange.

Low-Temperature and Template-Free Synthesis of ZnIn2S4 Microspheres

Porous ZnIn2S4 microspheres have been successfully synthesized by means of a facile thermal solution method at 353 K. This method was a simple route that involved low temperature, no templates, no catalysts, no surfactants, or organic solvents. Scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, nitrogen sorption analysis, and a UV-vis spectrophotometer were used to characterize the products. The results demonstrated that the microspheres, which were composed of many ZnIn2S4 single crystal nanosheets, underwent the Oswald ripening and self-assembly processes. A morphology formation mechanism has been proposed and discussed. The porous ZnIn2S4 product showed an enhancing visible-light photocatalytic activity for methyl orange degradation. The as-grown architectures may have potential applications in solar energy conversion, environmental remediation, and advanced optical/electric nanodevices.

Preparation of Fe 3+-doped TiO 2 catalysts by controlled hydrolysis of titanium alkoxide and study on their photocatalytic activity for methyl orange degradation

Fe 3+-doped TiO 2 (Fe–TiO 2) porous microspheres were prepared by controlled hydrolysis of Ti(OC 4H 9) 4 with water generated “in situ” via an esterification reaction between acetic acid and ethanol, followed by hydrothermal treatment. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic absorption flame emission spectroscopy (AAS), electron paramagnetic resonance (EPR) spectrum, X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), and nitrogen adsorption–desorption methods. All of the undoped TiO 2 and Fe–TiO 2 samples exclusively consist of primary anatase crystallites, which further form porous microspheres with diameters ranging from 150 to 500 nm. The photocatalytic activity of Fe–TiO 2 catalysts was evaluated from the photodegradation of methyl orange (MO) aqueous solution both under UV and visible light irradiation. Fe 3+ doping effectively improves the photocatalytic activity under both UV light irradiation and visible light irradiation with an optimal doping concentration of 0.1 and 0.2%, respectively. The photocatalytic mechanisms of Fe–TiO 2 catalysts were tentatively discussed.

Preparation of Au/TiO2 catalysts from Au(I)–thiosulfate complex and study of their photocatalytic activity for the degradation of methyl orange

Gold loaded on TiO2 (Au/TiO2) catalysts were prepared using Au(I)–thiosulfate complex (Au(S2O3)23−) as the gold precursor for the first time. The samples were characterized by UV–vis diffuse reflectance spectra, X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic absorption flame emission spectroscopy (AAS), and X-ray photoelectron spectroscopy (XPS) methods. Using Au(S2O3)23− as gold precursor, ultra-fine gold nanoparticles with a highly disperse state can be successfully formed on the surface of TiO2. The diameter of Au nanoparticles increases from 1.8 to 3.0nm with increasing the nominal Au loading from 1% to 8%. The photocatalytic activity of Au/TiO2 catalysts was evaluated from the analysis of the photodegradation of methyl orange (MO). With the similar Au loading, the catalysts prepared with Au(S2O3)23− precursor exhibit higher photocatalytic activity for methyl orange degradation when compared with the Au/TiO2 catalysts prepared with the methods of deposition–precipitation (DP) and impregnation (IMP). The preparation method has decisive influences on the morphology, size and number of Au nanoparticles loaded on the surface of TiO2 and further affects the photocatalytic activity of the obtained catalysts.