Characterization of TiO2 Loaded on Activated Carbon Fibers and Its Photocatalytic Reactivity

In this paper, TiO2 loaded on activated carbon fibers （ACF） was prepared by a coating treatment, followed by calcination at different temperatures in air atmosphere. The photocatalyst developed was characterized by SEM, XRD, XPS and UV-Vis adsorption spectroscopy. It was observed from SEM images that TiO2 loaded on ACF was in the form of small clusters with nanometer size. As confirmed by XRD and XPS determinations, the crystalline pattern of immobilized TiO2 was still anatase-form after calcination, and the micrographic structure and surface properties of ACF have not been damaged by the deposition process and calcination at different temperatures. Photocatalytic degradation of methylene blue （MB） in aqueous .solution was investigated using TiOE/ACF as photocatalyst. The comparison of photolysis, absorption and photocatalysis was carded out. The results indicated that the photocatalysis process of combined photocatalyst showed much higher degradation rate than that of photolysis and absorption processes. In addition, the possibility of cyclic usage of the photocatalyst was also confirmed.     

Crystal structure and DNA binding studies of a cobalt(Ⅱ) complex containing mixed-ligands of 1,10-phenathroline and glycollic acid

A cobalt（11） complex containing mixed-ligands of 1,10-phenathroline（phen） and glycollic acid（GA）.|Co（GA）₂（phen）| was synthesized and its structure was characterized by X-ray diffraction.The interaction of the complex with DNA was investigated by electronic absorption spectra and electrochemical methods.Electronic absorption spectrum experiments showed that after interaction with DNA.the characteristic absorption peaks of |Co（GA）₂（phen）| underwent hypochromic effect as well as redshift. Also,the binding strength of 3.8×10⁴L/mol was estimated by titration method.Electrochemical assays revealed that the redox peak currents of the complex decreased obviously accompanied by a positive shift of the formal potential after association with DNA.All these results revealed that the synthesized cobalt complex bound with DNA via an intercalation mode.     

Oxygen permeation and phase structure properties of partially A-site substituted BaCo_(0.7)Fe_(0.225)Ta_(0.075)O_(3-δ) perovskites

Ba0.9R0.1Co0.7Fe0.225Ta0.075O3-δ(BRCFT, R = Ca, La or Sr) membranes were synthesized by a solid-state reaction. Metal cation Ca2+,La3+or Sr2+doping on A-site partially substituted Ba2+in BaCo0.7Fe0.225Ta0.075O3-δoxides, and its subsequent effects on phase structure stability, oxygen permeability and oxygen desorption were systematically investigated by XRD, TG-DSC, H2-TPR, O2-TPD techniques and oxygen permeation experiments. The partial substitution with Ca2+, La3+or Sr2+, whose ionic radii are smaller than that of Ba2+, succeeded in stabilizing the cubic perovskite structure without formation of impurity phases, as revealed by XRD analysis. Oxygen-involving experiments showed that BRCFT with A-site fully occupied by Ba2+exhibited good oxygen permeation flux under He flow, reaching about 2.3mL min-1 cm-2at 900 ℃ with 1 mm thickness. Of all the membranes, BLCFT membrane showed better chemical stability in CO2, owing to the reduction in alkalinity of the mixed conductor oxide by La doping. In addition, we also found the stability of the perovskite structure under reducing atmospheres was strengthened by increasing the size of A-site cation(Ba2+La3+Sr2+Ca2+).     

Electrospinning Preparation of β-Cyclodextrin/Glutaraldehyde Crosslinked PVP Nanofibrous Membranes to Adsorb Dye in Aqueous Solution

The insoluble β-cyclodextrin/glutaraldehyde crosslinked polyvinylpyrrolidone nanofibrous membranes were prepared by electrospinning technique. The membranes were extensively characterized by various techniques including attenuated total reflectance Fourier transform infrared spectroscopy（ATR-FTIR）, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and UV-visible absorption to correlate membrane characteristics with their performance. The adsorption ability of the nanofibrous membranes was tested by performing extraction of Methyl orange（MO） dye in water. It was observed that β-cyclodextrin incorporated in polyvinylpyrrolidone provided the characteristics of high adsorption capacity of polyvinylpyrrolidone. Results of sorption experiments show that the nanofibrous membranes exhibited an adsorption rate of more than 95% for MO and the MO absorbent was 39.82 mg to per gram of fl-cyclodextrin glutaraldehyde（β-CDXFM） crosslinked PVP under the optimized experimental conditions.     

Preparation of La-Mo-V mixed-oxide systems and their application in the direct synthesis of acetic acid

In this study, mixed metal oxides developed with a perovskite-type structure that show great potential for use in catalysis. Perovskite oxide catalysts with the composition LaMoxV1-xOn （x = 0.1, 0.3, 0.5, 0.7, and 0.9） have been synthesized by the sol-gel method and then used in the ethane dry reforming reaction for the direct synthesis of acetic acid. The influence of the nature of the metallic source （metal, nitrate, acetylacetonate, and ammonium） on gel formation has been studied by Fourier-transform infrared spectroscopy （FT-IR） and thermogravimetric analysis （TGA-DTA）. After calcination, the obtained perovskites were characterized by X-ray diffraction （XRD） and energy-dispersive X-ray spectrometry （EDS） coupled with scanning electron microscopy （SEM）. The catalysts were then subjected to thermo-programmed reduction （TPR）. The surface area （BET） was found to increase from 2.6 m^2/g （x = 0.1） to 5.1 m2/g （x = 1.0） with increasing molybdenum content following calcinations at 750 °C, and pure LaMoxV1-xOn perovskite was obtained with good homogeneity. The catalysts have been characterized by XRD, SEM, EDS, and carbon analysis （CA）. The results indicate that through this synthesis it is possible to obtain highly crystalline, homogeneous and pure solids, with well-defined structures. The direct synthesis of acetic acid from ethane over the perovskite catalysts was studied at temperatures between 450 and 850 °C and elevated pressures between 1 and 8 bar. It was found that the yield of acetic acid and the selectivity of its formation could be increased by incorporating more molybdenum into the perovskite structure. The experimental studies have shown that the calcination temperature and the molybdenum content have a significant influence on the catalytic activity. Amongst the catalysts tested, LaMo0.7V0.3O4.2 exhibited the best activity and stability.     

Operando HERFD-XANES and surface sensitive Δμ analyses identify the structural evolution of copper(Ⅱ) phthalocyanine for electroreduction of CO2

The quantitative understanding of how atomic-level catalyst structural changes affect the reactivity of the electrochemical CO₂reduction reaction is challenging.Due to the complexity of catalytic systems,conventional in situ X-ray spectroscopy plays a limited role in tracing the underlying dynamic structural changes in catalysts active sites.Herein,operando high-energy resolution fluorescence-detected X-ray absorption spectroscopy was used to precisely identify the dynamic structural transformation of well-defined active sites of a representative model copper(Ⅱ)phthalocyanine catalyst which is of guiding significance in studying single-atom catalysis system.Comprehensive X-ray spectroscopy analyses,including surface sensitive△μspectra which isolates the surface changes by subtracting the disturb of bulk base and X-ray absorption near-edge structure spectroscopy simulation,were used to discover that Cu species aggregated with increasing applied potential,which is responsible for the observed evolution of C₂H₄.The approach developed in this work,characterizing the active-site geometry and dynamic structural change,is a novel and powerful technique to elucidate complex catalytic mechanisms and is expected to con tribute to the rational design of highly effective catalysts.     

热处理对SILAR法制备CuInSe2薄膜性能的影响

CuInSe₂ ternary films were prepared by successive ionic layer absorption and reaction (SILAR) method. The films were deposited on glass substrates at room temperature and subject to heat-treatment under Ar atmosphere at various calcination temperatures, and then characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), optical absorption spectroscopy. XRD results showed that chalcopyrite structure CuInSe₂ with high degree of preferred orientation towards (112) reflection could be obtained by post-heat treatment. The compositions of films calcined at 300～400 ℃ were close to the standard stoichiometry and Cl impurity decreased after calcination. The direct band gap increased from 0.94 eV to 0.98 eV with the increase of calcination temperature.     

Low temperature preparation of flower-like BiOCl film and its photocatalytic activity

The BiOCl thin film with flower-like sphere structure was prepared at a low temperature by the alcoholysis-coating method using BiCl 3 as precursor. The obtained thin film was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), electronic energy spectrum (EDS) and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). And the results showed that the obtained BiOCl film without calcination was composed of flower-like sphere structure with tetragonal phase and had a good absorption for ultraviolet. The photocatalytic activity of BiOCl thin film was also evaluated by the degradation of methyl orange in water under UV light irradiation. The degradation experimental results confirmed that the film prepared at low temperature possessed a high photocatalytic activity and could achieve 97% degradation to 10 mg/L methyl orange solution after 150 min UV light irradiation. The stability of the obtained BiOCl thin film was also good and its photocatalytic activity still remained an above 94% removal of methyl orange after being used four times. In addition, a possible formation mechanism of BiOCl thin film was also inferred and the results suggested that the ethylene glycol solvent may contribute to the forming flower-like sphere structure.     

Double perovskite oxides Sr_2Mg_(1-x)Fe_xMoO(6-δ) for catalytic oxidation of methane

The double perovskite oxides Sr2Mg1-xF exMoO6-δ were investigated as catalysts for the methane oxidation.The structural properties of catalysts were characterized in detail by X-ray diffraction,X-ray photoelectron spectroscopy and X-ray absorption spectroscopy.The catalytic property was strongly influenced by the Fe substitution.The relation between catalytic performance and the degree of Fe substitution was examined with regard to the structure and surface characteristics of the mixed oxides.The Fe-containing catalysts exhibited higher activity attributable to the possible(Fe2+,Mo6+) and (Fe3+,Mo5+)valency pairs,and the highest activity was observed for Sr2Mg0.2Fe0.8MoO6-δ.The enhancement of the catalytic activity may be correlated with the Fe-relating surface lattice oxygen species and was discussed in view of the presence of oxygen vacancies.     

Preparation of Thermal-responsive Chitosan-graft-N-isopropylacrylamide Membranes via γ-Ray Irradiation

A novel thermo-sensitive switching membrane has been prepared by radiation-induced simultaneous grafting N-isopropylacrylamide （NIPAAm） onto chitosan membrane. Fourier transform infrared spectroscopy （FTIR） was used to identify the structure of the grafted membranes. The surface morphology of the grafted membrane was observed from scanning electron microscopy （SEM）. Pure water flux measurements showed that water flux of the grafted membrane decreased with the increase of temperature, while that of chitosan membrane was constant. It was proved that grafted membrane was sensitive to temperature.     

Nickel ferrite spinel as catalyst precursor in the dry reforming of methane:Synthesis,characterization and catalytic properties

Dry reforming of methane by CO2 using nickel ferrite as precursor of catalysts was investigated.Nickel ferrite crystalline particles were prepared by coprecipitation of nitrates with NaOH or ammonia followed by calcination,or by hydrothermal synthesis without calcination step.The textural and structural properties were determined by a number of analysis methods,including X-ray diffraction (XRD),Raman spectroscopy and X-ray photoelectron spectroscopy (XPS),among which X-ray diffraction (XRD) was at room and variable temperatures.All synthesized oxides showed the presence of micro or nanoparticles of NiFe2O4 inverse spinel,but Fe2O3 (hematite) was also present when ammonia was used for coprecipitation.The reducibility by hydrogen was studied by temperature-programmed reduction (TPR) and in situ XRD,which showed the influence of the preparation method.The surface area (BET),particle size (Rietveld refinement),as well as surface Ni/Fe atomic ratio (XPS) and the behavior upon reduction varied according to the synthesis method.The catalytic reactivity was investigated using isopropanol decomposition to determine the acid/base properties.The catalytic performance of methane reforming with CO2 was measured with and without the pre-treatment of catalysts under H2 in 650-800 C range.The catalytic conversions of methane and CO2 were quite low but they increased when the catalysts were pre-reduced.A significant contribution of reverse water gas shift reaction accounted for the low values of H2 /CO ratio.No coking was observed as shown by the reoxidation step performed after the catalytic reactions.The possible formation of nickel-iron alloy observed during the study of reducibility by hydrogen was invoked to account for the catalytic behavior.     

Fabrication and Visible Light Photocatalytic Activity of Co-doped ZnO Nanorods

Co-doped ZnO nanorods were prepared by electrochemical deposition method in aqueous solution. lb study the as-grown samples, several characterizations were carried out. The scanning electron microscopy（SEM） images show that the samples present a rod-like shape with hexagonal cross sections and roughened surthce. There is a slight shift for （002） diffraction peak of Co-doped ZnO nanorods in XRD because Co2~ ions entered into the ZnO lattice. Energy-dispersive X-ray spectroscopy（EDS） and X-ray photoelectron spectroscopy（XPS） results also show the exist of Co in the sample. Photoluminescence（PL） spectra of the samples were observed at room tempera- ture, the UV emission of Co-doped ZnO shows a slight red shift compared with that of undoped ZnO. Thus, we can reach the conclusion that Zn2＋ ions have been substituted by Co2. ions in the ZnO samples. In addition, photocatalysis property of Co-doped ZnO nanorods was investigated under the irradiation of visible light. It was found that the degradation rate of methyl orange is increased greatly nanorods. by Co-doped ZnO nanorods in comparison to undoped ZnO     

Research on KOH/La-Ba-Al2O3 catalysts for biodiesel production via transesterification from microalgae oil

Alumina supports modified by lanthanum(La)and barium(Ba)were prepared by peptization.Catalysts with different KOH contents supported on modified alumina were prepared by impregnation method.Various techniques,including N2 adsorption-desorption(Brunauer-Emmet-Teller method,BET),X-ray diffraction(XRD),scanning electron microscopy(SEM),and fourier transform infrared absorption spectroscopy(FT-IR). Catalytic activity for microalgae oil conversion to methyl ester via transesterification was evaluated and analyzed by GC-MS and GC.BET results showed that the support possessed high specific surface area,suitable pore volume and pore size distribution.Activity results indicated that the catalyst with 25 wt%KOH showed the best activity for microalgae oil conversion.XRD and SEM results revealed that Al-O-K compound was the active phase for microalgae oil conversion.The agglomeration and changing of pore structure should be the main reasons for the catalyst deactivation when KOH content was higher than 30 wt%.     

Partial oxidation of methane in Ba0.5Sr0.5Co0.8Fe0.1Ni0.1O3-δ ceramic membrane reactor

Ba0.5Sr0.5Co0.8Fe0.1Ni0.1O3δ(BSCFNiO) perovskite oxides were synthesized using a combined EDTA-citrate complexation method,and then pressed into disk and applied in a membrane reactor.The performance of the BSCFNiO membrane reactor was studied for partial oxidation of methane over Ni/α-Al 2 O 3 catalyst.The time dependence of oxygen permeation rate and catalytic performance of BSCFNiO membrane during the catalyst initiation stage were investigated at 850 C.In unsteady state,oxygen permeation rate,methane conversion and CO selectivity were closely related to the state of the catalyst.After 300 min from the initial time,the reaction condition reached to steady state and oxygen permeation rate were obtained about 11.7cm 3 cm 2 min 1.Also,the performance of membrane reactor was studied at the temperatures between 750 and 950 C.The results demonstrated good performance for the membrane reactor,as CH 4 conversion and CO selectivity permeation rate reached 98% and 97.5%,respectively,and oxygen permeation rate was about 14.5 cm 3 cm 2 min 1 which was 6.8 times higher than that of air-helium gradient.Characterization of membrane surface by SEM after reaction showed that the original grains disappeared on both surfaces exposed to the air and reaction side,but XRD profile of the polished surface membrane indicated that the membrane bulk preserved the perovskite structure.     

Hydrophilic nanofiltration membranes with self-polymerized and strongly-adhered polydopamine as separating layer

Inspired by the self-polymerization and strong adhesion characteristics of dopamine in aqueous conditions,a novel hydrophilic nanofiltration（NF） membrane was fabricated by simply dipping polysulfone（PSf） ultrafiltration（UF） substrate in dopamine solution.The changes in surface chemical composition and morphology of membranes were determined by Fourier transform infrared spectroscopy（FTIR-ATR）,X-ray photoelectron spectroscopy（XPS）,scanning electron microscopy（SEM） and atomic force microscopy（AFM）.The experimental results indicated that the self-polymerized dopamine formed an ultrathin and defect-free barrier layer on the PSf UF membrane.The surface hydrophilicity of membranes was evaluated through water contact angle measurements.It was found that membrane hydrophilicity was significantly improved after coating a polydopamine（pDA） layer,especially after double coating.The dyes filtration experiments showed that the double-coated membranes were able to reject completely the dyes of brilliant blue,congo red and methyl orange with a pure water flux of 83.7 L/（m²·h） under 0.6 MPa.The zeta potential determination revealed the positively-charged characteristics of PSf/pDA composite membrane in NF process.The salt rejection of the membranes was characterized by 0.01 mmol/L of salts filtration experiment.It was demonstrated that the salts rejections followed the sequence:NaCl2SO₄422,and the rejection to CaCl₂ reached 68.7%.Moreover,the composite NF membranes showed a good stability in water-phase filtration process.     

Temperature-dependent structural changes of[Bmim]FeCl4 magnetic ionic liquid characterized by an in-situ X-ray absorption fine structure

The temperature-dependent structural changes in 1-butyl-3-methylimidazolium tetrafluoride([Bmim]FeCl4)magnetic ionic liquid(MIL)were investigated by using in-situ X-ray absorption fine structure(XAFS)combined with Raman spectroscopy and DFT calculations.XAFS re sults revealed that the coordination number and bond length of Fe-Cl in the anion of[Bmim]FeCl4 MIL decreased with increments in temperature.These results directly reflected the dissociation of tetrahedral structure[FeCl4]^-,and the formation of bridge-chain[Fe2 Cl5]^+,and[FeCl2]^+species in the anion of[Bmim]FeCl4 MIL.These behaviors indicated that[FeCl4]^-dissociation was endothermic,and was promoted by increased temperature.The results obtained through XAFS were in agreement with those obtained through Raman spectroscopy and DFT calculations.     

Ruthenium promotion of Co/SBA-15 catalysts for Fischer-Tropsch synthesis in slurry-phase reactors

The aim of this work was to evaluate the catalytic properties of a Ru promoted Co/SBA-15 catalyst for Fischer-Tropsch synthesis(FTS).The Ru promoted Co/SBA-15 catalyst was prepared by wet impregnation method and was characterized by X-ray diffraction,X-ray energy dispersion spectrophotometer,N2 adsorption-desorption,temperature-programmed reduction and transmission electron microscopy.The Fischer-Tropsch synthesis using the catalyst was carried out to evaluate the catalyst activity and its effect on FTS product distribution.The synthesis was carried out in a slurry reactor operating at 513 K,20 atm,CO:H2 molar ratio of 1:1.X-ray diffraction showed that the calcined cobalt catalyst did not modify the structure of SBA-15,proving that Co was present in the form of Co3O4 in the catalyst.The addition of cobalt in SBA-15 decreased the specific superficial area of the molecular sieve.Fischer-Tropsch synthesis activity and C5+hydrocarbon selectivity increased with the addition of Ru.The increases in activity and selectivity were attributed to the increased number of active sites resulting from higher reducibility and the synergetic effect of Ru and Co.Ru/Co/SBA-15 catalysts showed moderate conversion(40%)and high selectivity towards the production of C5+(80 wt%).     

SURFACE MODIFICATION OF POLYPROPYLENE MICROPOROUS MEMBRANE BY TETHERING POLYPEPTIDES

Two kinds of polypeptides were tethered onto the surface of polypropylene microporous membrane （PPMM） through a ring opening polymerization of L-glutamate N-carboxyanhydride initiated by amino groups which were introduced by ammonia plasma and y-aminopropyl triethanoxysilane treatments. X-ray photoelectron spectroscopy （XPS）, attenuated total reflectance Fourier transform infrared spectroscopy （FT-IR/ATR）, scanning electron microscopy （SEM）, together with water contact angle measurements were used to characterize the modified membranes. XPS analyses and FT-IR/ATR spectra demonstrated that polypeptides are actually grafted onto the membrane surface. The wettability of the membrane surface increases at first and then decreases with the increase in grafting degrees of polypeptide. Platelet adhesion and murine macrophage attachment experiments reveal an enhanced hemocompatibility for the polypeptide modified PPMMs. All these results give evidence that polypeptide grafting can simultaneously improve the hemocompatibility as well as reserve the hydrophobicity for the membrane, which will provide a potential approach to improve the performance of polypropylene hollow fiber microporous membrane used in artificial oxygenator.     

Efficient CO_2 Electrolysis with Fluorite Structure Nanoparticles Modified Perovskite Structure La_(0.75)Sr_(0.25)Cr_(0.5)Mn_(0.5)O_(3-δ) Cathode

Perovskite structure La_(0.75)Sr_(0.25)Cr_(0.5)Mn_(0.5)O_(3-δ)(LSCM) cathode with unique structure can electrolyze CO_2 to CO in solid oxide electrolysers(SOEs).However,the cell performance is restricted by its electro-catalysis activity.In this work,fluorite structure nanoparticles(CeO_(2-δ)) are impregnated on LSCM cathode to improve the electro-catalysis activity.X-ray diffraction(XRD),scanning electron microscope(SEM) and X-ray photoelectron spectroscopy(XPS) together approve that the fluorite structure nanoparticles are uniformly distributed on the perovskite structure LSCM scaffold.Electrochemical measurements illustrate that direct CO_2 electrolysis with 10%mol CeO_(2-δ) impregnated LSCM cathode exhibits excellent performance for current density(0.5 A×cm~(-2)) and current efficiency(～95%) at 800 ℃ under 1.6 V.It is believed that the enhanced performance of directed CO_2 electrolysis may be due to the synergetic effect of fluorite structure CeO_(2-δ) nanoparticles and perovskite structure LSCM ceramic electrode.     

Preparation of α-Fe2O3 Nanofiber via Electrospinning Process

A thin PVA/FeCl3 composite fiber was prepared by using sol-gel processing and electrospinning techniques. A nanofiber of α-Fe2O3 with the diameter of 50-150 nm was obtained via high temperature calcination of the PVA/FeCl3 composite fiber. The material was characterized by infra-red (IR) spectroscopy, X-ray diffraction(XRD), and scanning electron microscopy(SEM). The results show that the fiber after the calcination at 700℃ was a pure α-Fe2O3 nanofiber.