Surfactant-assisted Co-precipitation Method Research Articles

Catalytic Dry-reforming of Methane Process with Co,Ni,Pd/Ca-La-O Mixed Oxides

A surfactant-assisted co-precipitation method was used to prepare the catalysts Co,Ni,Pd/CaO, Co,Ni,Pd/Ca0.97La3+0.03O, Co,Ni,Pd/Ca0.93La3+0.07O, and Co,Ni,Pd/Ca0.85La3+0.15O (1% each of Co, Ni, and Pd). La2O3 doping effect on the activity and stability of Co,Ni,Pd/CaO catalysts was investigated in dry reforming of methane. Catalysts were characterized by several techniques (X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), X-ray Fluorescence (XRF), Fourier Transform Infra Red (FTIR), Temperature Programmed Desorption H2 (H2-TPR), Transmission electron microscopes (TEM), and Temperature Gravimetric Analysis (TGA)) and were tested in a fixed-bed reactor at 900 °C and (Gas Hourly Specific Velocity (GHSV) = 15000 mL.gcat−1.h−1, atmospheric pressure). Adding La2O3 had little effect on the morphology of the Co,Ni,Pd/CaO catalyst. However, it played a crucial role in enhancing the catalyst’s reducibility and CO2 adsorption at high temperatures, as indicated by the activity and stability of the Co,Ni,Pd/CaO catalyst. The carbon deposition on utilized catalysts after 5 hours at 900 °C was examined using TEM and thermal gravimetric analysis (TGA) techniques. Compared to Co,Ni,Pd/CaO catalysts across the entire temperature range, the tri-metallic Co,Ni,Pd/Ca0.85La3+0.15O catalyst with a lanthanum promoter demonstrated a greater conversion of CH4 (84%) and CO2 (92 %) at a 1:1 CH4:CO2 ratio. The selectivity of H2/CO reduced in the following order: Co,Ni,Pd/Ca0.85La3+0.15O > Co,Ni,Pd/Ca0.93La3+0.07O > Co,Ni,Pd/Ca0.97La3+0.03O > Co,Ni,Pd/CaO. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

CuO induced effects on the electrochemical properties of (In2O3)1-xCuOx nanocomposites for supercapacitor flexible electrode materials

• Novel (In 2 O 3 ) 1-x CuO x heterostructure nanocomposites with different concentration was fabricated through the surfactant-assisted co-precipitation method. • The electrochemical performance and electrochemical cycle stability of all the prepared samples were assessed over the carbon cloth (CC) electrode. • The (In 2 O 3 ) 0.5 (CuO) 0.5 was demonstrated higher capacitance 883 F/g at 1A/g than all other samples. • Approximately 83.5% capacity retention after 6000 GCG tests was measured for (In 2 O 3 ) 0.5 (CuO) 0.5 . Recent research on electrochemical energy storage devices has shown that their specific capacities, cyclic-lives, as well as rate performances, are chiefly controlled by their electrodes. Therefore, a key challenge for 21st-century material researchers is to seek out novel electrode materials with improved crystal structures, excellent specific capacities and better electronic conductivities, in order to fabricate a highly efficient energy storage system. To address this concern (In 2 O 3 ) 1-x CuO x (where x = 0, 0.1, 0.3, 0.5, 0.7, 1) heterostructure nanocomposites have been prepared through the surfactant-assisted co-precipitation strategy. The nature of the atomic and molecular interactions, chemical compositions, textures and shapes of the synthesized nanocomposites have been investigated in detail. In this study, the novel composite materials have been supported over carbon cloth (CC) to produce flexible working electrodes. It has been found that the electrode with a particular composition of (In 2 O 3 ) 0.5 (CuO) 0.5 -over-CC has demonstrated superior capacitance (883 F/g at 1 A/g), improved electrochemical and cycle stability (83.5 % after 6000 GCD tests) and a higher rate capability (708 F/g at 5 A/g) than all other fabricated nanocomposite-based flexible electrodes. The electrode's improved electrochemical activity is attributed to its flexible design, higher electronic conduction, non-resistive current collector behaviour and unique nanoarchitecture. These versatile and simple-to-prepare nanocomposites are potential candidates as electrodes for high-performance pseudocapacitors nanodevices.

Effect of zinc substitution on magnesium ferrite nanoparticles: Structural, electrical, magnetic, and gas-sensing properties

In this study, we fabricated zinc-substituted magnesium ferrite (MgFe2O4) (ZMF) nanoparticles with the general formula ZnxMg1−xFe2O4 (x = 0.00–0.75) using a surfactant-assisted co-precipitation method and evaluated their H2S gas-sensing performance. Fourier-transform infrared and X-ray diffraction analysis results reveal the formation of a cubic spinel ferrite structure. The effect of zinc substitution on the physico-chemical properties of MgFe2O4 was studied and is discussed herein. The polycrystalline ZMF nanoparticles are magnetic and showed advantageous gas-sensing performance, the results of which reveal that they are sensitive to and selective for hydrogen sulfide (H2S) gas. The ZMF gas sensors exhibited good sensing of various test gases/vapors, such as H2S, H2, Cl2, carbon dioxide, liquid petroleum gas, ammonia, and ethanol while working at room temperature to 400 °C. The Zn0.5Mg0.5Fe2O4 composition produced the highest response toward 10 ppm H2S gas at 400 °C operating temperature.

Hydrogen production via steam reforming of glycerol over Rh/γ-Al2O3 catalysts modified with CeO2, MgO or La2O3

Abstract The glycerol steam reforming (GSR) reaction for hydrogen production was investigated over Rh-based catalysts supported on γ-Al2O3 modified with CeO2, MgO or La2O3. High specific surface area mesoporous supports (Al2O3, CeO2–Al2O3, MgO–Al2O3 and La2O3–Al2O3) were synthesized by the surfactant-assisted co-precipitation method using cetyltrimethylammonium bromide (CTAB) as template. Then, highly dispersed Rh-based catalysts were prepared by the wetness impregnation technique. The physico-chemical properties of the as-prepared supports and catalysts were investigated by N2-physisorption, XRD, ICP-AES, CO-chemisorption, TEM, H2-TPR, CO2-TPD and NH3-TPD measurements. Performance test experiments were carried out in a continuous flow fixed-bed reactor at water-to-glycerol feed ratio (WGFR) of 20:1 (molar), temperatures from 400 °C to 750 °C, weight hourly space velocity of 50,000 ml g−1 h−1 and atmospheric pressure. The stability of all catalysts was also investigated through 12 h time-on-stream (TOS) experiments at 600 °C using a WGFR of 9:1. All catalysts were remarkably stable during TOS with total glycerol conversion of ≈90%, glycerol conversion into gaseous products of ≈45% and H2 selectivity of ≈78%. The final H2 yield for all catalysts was 2.4–2.9 mol H2/mol glycerol. TEM experiments showed that the carbon formed onto the spent catalysts was amorphous and that sintering was mostly avoided during TOS, helping explain the excellent catalytic stability observed. The unpromoted catalyst seems to be following a different reaction pathway than and the promoted ones that depends strongly on the population and kind of acid and basic sites over its surface.

Facile synthesis of spherically SrWO4 nanomaterials via surfactant-assisted co-precipitation method: an affordable catalyst for the mitigation of carcinogenic organic dye

ABSTRACT In this scenario, a novel spherical like SrWO4 nanomaterial’s were made by the simple co-precipitation route was confirmed by various characterisation techniques. The Powder X-Ray diffraction (P-XRD) was explained the crystalline nature of the as-prepared materials; the obtained diffraction peaks reveal good crystalline nature of as prepared novel SrWO4 nanomaterials. The Williamson-Hall (W-H) plot method was used to analyse the individual role of particle sizes and lattice strain on the peak broadening of the NPs of host and surfactant doped SrWO4. The morphology of the host SrWO4 materials has been spherical, but also of surfactants, the morphology will be changed. The presenting elements and the oxidation state of Sr, O and W were confirmed by X-ray Photoelectron Spectroscopy analysis. Interestingly, SrWO4.SDS+PVP catalyst having an efficient activity in the degradation process than that others and the degradation efficiency 95.7% corresponds to methylene blue (MB) degradation within 90 mins. In Reactive Oxidative Species study, hydroxyl and superoxide radical’s quenchers are the main reactive species in the MB degradation process. On the other hand, the recycling test has confirmed the stability and reusability of the catalysts.

Effect of La2O3 as a Promoter on the Pt,Pd,Ni/MgO Catalyst in Dry Reforming of Methane Reaction

Pt,Pd,Ni/MgO, Pt,Pd,Ni/Mg0.97La3+0.03O, Pt,Pd,Ni/Mg0.93La3+0.07O, and Pt,Pd,Ni/Mg0.85La3+0.15O (1% of each of the Ni, Pd, and Pt) catalysts were prepared by a surfactant-assisted co-precipitation method. Samples were characterized by the XRD, XPS, XRF, FT-IR, H2-TPR, TEM, the Brunauer–Emmett–Teller (BET) method, and TGA and were tested for the dry reforming of methane (DRM). TEM and thermal gravimetric analysis (TGA) methods were used to analyze the carbon deposition on spent catalysts after 200 h at 900 °C. At a temperature of 900 °C and a 1:1 CH4:CO2 ratio, the tri-metallic Pt,Pd,Ni/Mg0.85La3+0.15O catalyst with a lanthanum promoter showed a higher conversion of CH4 (85.01%) and CO2 (98.97%) compared to the Ni,Pd,Pt/MgO catalysts in the whole temperature range. The selectivity of H2/CO decreased in the following order: Pt,Pd,Ni/Mg0.85La3+0.15O > Pt,Pd,Ni/Mg0.93La3+0.07O > Pt,Pd,Ni/Mg0.97La3+0.03O > Ni,Pd,Pt/MgO. The results indicated that among the catalysts, the Pt,Pd,Ni/Mg0.85La23+0.15O catalyst exhibited the highest activity, making it the most suitable for the dry reforming of methane reaction.

Low-pressure hydrogenation of CO2 to methanol over Ni-Ga alloys synthesized by a surfactant-assisted co-precipitation method and a proposed mechanism by DRIFTS analysis

Ni-Ga alloy catalysts were synthesized by a surfactant-assisted co-precipitation method and were tested in CO2 hydrogenation to methanol at 10 bar and at ambient pressure. The presence of surfactant in the synthesis led to a decrease in particle size, with the catalyst produced using 1% of surfactant (C_1%) presenting the smallest and most homogeneous particle size. A difference between the catalysts was also observed in the change of the crystalline phase after the reaction, where the C_1% catalyst presented the lowest loss of the Ni5Ga3 active phase. Methanol productivity showed positive relations with smaller particle size and higher quantity of Ni5Ga3 crystalline phase remaining after the reaction, with the C_1% catalyst presenting the highest methanol productivity. Catalytic evaluation under different conditions showed that higher temperature and GHSV values led to poorer selectivity to methanol. The C_1% catalyst also presented good activity at ambient pressure and remained stable after 5 h, with no deactivation. A mechanistic study employing DRIFTS analyses found that the reaction pathway on Ni-Ga alloy involved both the RWGS and formate routes, as shown by the presence of formate, methoxy, and CO intermediates.

Physical, Structural and Dielectric Parameters Evaluation of New Mg1-x Cox NiyFe2-yO4 nano-ferrites Synthesized via Wet Chemical Approach

Department of Chemistry, Institute of Natural Sciences, University of Gujrat, Gujrat 50700, Pakistan The surfactant assisted co-precipitation method has been used to synthesize the Co2+ and Ni2+ substituted magnesium nanoferrites. The Co2+ and Ni2+ ions substitute the Mg2+ and Fe3+ ions from the magnesium ferrites, respectively. To study the effect of substituted ion concentrations on the dielectric performance of the MgFe2O4 spinel ferrites. The substituted magnesium nanoferrites with the compositions Mg1-x Cox NiyFe2-yO4 (x, y = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) were synthesized to notice the effect of substituted ions concentration on the dielectric properties. Thermogravimetric analysis of the precursor precipitates was taken to investigate the stable spinel phase formation temperature. The X-ray diffraction analysis of the all substituted samples confirms the successful formation of the stable spinel phase and also exposes the effects of substituted ions on the crystal structure and unit cell constants. The presence of a characteristic absorption band (400 cm−1, 550 cm−1) of spinel ferrites in the Fourier Transform Infra Red (FT-IR) spectrum of substituted magnesium nanoferrites also confirms the formation of desire phase. The effect of temperature on the conductivity of the all substituted samples was observed within the temperature range of 25°C–300°C by two-probe direct current electrical resistivity measurements. Dielectric measurements of the substituted magnesium nanoferrites were carried out to study their magnetic behavior. The inverse relation of the dielectric parameters of the all substituted magnesium nanoferrites with frequency shows their excellent potential for devices that operate at higher frequencies.Department of Chemistry, University of Okara, Renala Khurd, Okara, Pakistan Department of Chemistry, Allama Iqbal Open University, H-8, Islamabad 45320, Pakistan.

Hydrogen production from ethanol steam reforming over Co–Ce/sepiolite catalysts prepared by a surfactant assisted coprecipitation method

A series of Co–Ce/Sepiolite (SEP) catalysts were prepared by surfactant-assisted coprecipitation route and subsequently evaluated for hydrogen production from ethanol steam reforming. The effects of the types and quantities of surfactants such as Cetyltrimethyl Ammonium Bromide (CTAB) and Polyvinyl Pyrrolidone (PVP) on catalysts microstructures were investigated by means of N2 adsorption-desorption, XRD, H2-TPR, Raman, XPS, SEM, and TEM. The results demonstrated that the function of surfactants complexation with Co/Ce precursors enlarged the metal interparticle distance, led to the surface enrichment of Co/Ce atoms and provoked diverse Co–Ce interfaces, which could both enhance the reforming behavior and restrain the amorphous coke during reaction. Meanwhile, the optimal complexation effect of CTAB on Co–Ce/SEP-C0.4 (CTAB:Mδ+ = 0.4) gave it superior reducibility, surface content of Co/Ce atoms and relative abundance of oxygen vacancies. Consequently, Co–Ce/SEP-C0.4 presented the best ethanol conversion (96.2%), hydrogen yield (77.9%) and the uppermost catalytic stability (100 h) during ESR reaction. In addition, the scatter modes of surface Co/Ce particles and forms of Co–Ce interfaces significantly depended on surfactant types.

The impact of carbon nanotubes on the optical, electrical, and magnetic parameters of Ni2+ and Co2+ based spinel ferrites

Surfactant-assisted co-precipitation method was used to synthesize Ni2+ and Co2+ based spinel ferrite nanoparticles. These ferrites are NiFe2O4, CoFe2O4, and Ni0.4Co0.6Fe2O4. The structural elucidation of the synthesized nanoparticles was carried by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). Both XRD and FTIR confirmed the spinel structure of prepared ferrite nanoparticles. The Debye-Scherrer equation showed the crystallite size in the range 6–15 nm. This range of particles size is an excellent range for a good signal to noise ratio. XRD result showed that the lattice constant value in Ni0.4Co0.6Fe2O4 decreased with increase in nickel ion concentration. FTIR revealed vibrational frequencies due to the presence of certain functional groups and octahedral and tetrahedral sites of ferrites nanoparticles. Nanocomposites of carbon nanotubes (CNTs) with spinel ferrite nanoparticles were prepared. CNTs influenced the various properties of spinel ferrite nanoparticles. The most affected properties are optical band gap, magnetic properties, dielectric properties, and photocatalytic applications. Ultraviolet–visible spectroscopy was used to study optical properties and photocatalysis. A Tauc plot showed a decrease in nanocomposite band gap values, due to the lower band gap of CNTs. Heterostructures of Ni0.4Co0.6Fe2O4 with carbon nanotubes showed enhanced magnetic behavior and low values of dielectric constant at high-frequency regions due to an increase in cobalt ion concentration. Photocatalytic activity was measured by the degradation of typical organic dye methylene blue (MB). UV–visible spectra of MB in presence of ferrite nanoparticles and their composites showed degradation of MB in visible light irradiation.

Effects of cerium precursors on surface properties of mesoporous CeMnOx catalysts for toluene combustion

Mesoporous CeMnOx composite oxides catalysts were prepared by surfactant-assisted co-precipitation method and used for the catalytic oxidation of toluene. The effect of different cerium precursors [Ce(NO3)3 and (NH4)2Ce(NO3)6] on catalyst structure, surface properties and toluene combustion activities of mesoporous CeMnOx catalysts were investigated. The Ce(III)MnOx catalyst prepared from Ce(NO3)3 precursor shows higher catalytic activity, with a 90% conversion temperature of 240 °C, which is better than the Ce(IV)MnOx catalyst derived from (NH4)2Ce(NO3)6] precursor. On the basis of characterizations, it reveals that abundant surface content of Mn4+, better redox behavior and larger concentration of surface active oxygen species are responsible for the excellent catalytic performance.

Reduced graphene oxide-spinel ferrite nano-hybrids as magnetically separable and recyclable visible light driven photocatalyst

High quality magnetically separable Ni0.65Zn0.35Fe2O4 nanoparticles were synthesized by surfactant assisted co-precipitation method. Spinel structure of these ferrite nanoparticles was confirmed by X-ray diffraction (XRD). Reduced graphene oxide (rGO) was prepared by wet chemical approach and then utilized to make the composites with ferrite nanoparticles. The successful homogenous distribution of ferrites nanoparticles onto the graphene sheets was observed by scanning electron microscopic (SEM) analysis. The [email protected] composite exhibited the strong absorption in visible region as observed by UV–vis measurements. Optical band gap studies confirmed that the prepared spinel ferrite Ni0.65Zn0.35Fe2O4 nanoparticles can be utilized for visible light driven photocatalytic activity studies. The optical (direct) band gap for Ni0.65Zn0.35Fe2O4 nanoparticles as calculated by Tauc plot was found 1.91 eV. This bandgap lies in the visible region i.e. < 3.0 eV. The band gap of ferrite nanoparticles was reduced to 1.84 eV when they were mixed with rGO to prepare the nano-hybrids. The photocatalytic activity of the ferrite nanoparticles was analyzed by photochemical decomposition of methylene blue (MB) under visible light irradiation. Photocatalytic activity of Ni0.65Zn0.35Fe2O4@rGO nano-hybrids was found better as compared to bare nanoparticles. Improved photodegradation of MB by NiZnFe2O4/rGO was ascribed due to effective separation of photo-generated electron-hole pairs. The ferrite nanoparticles exhibit ferromagnetic nature; therefore they can be recovered easily by conventional magnets. Thus these ferrite nanoparticles and their nano-hybrids with rGO can be recycled and reused easily.

Renewable hydrogen production via steam reforming of simulated bio-oil over Ni-based catalysts

The production of hydrogen via steam reforming (SR) of simulated bio-oil (glycerol, syringol, n-butanol, m-xylene, m-cresol, and furfural) was investigated over Ni/CeO2-Al2O3 and Me-Ni/CeO2-Al2O3 (Me = Rh, Ru) catalysts. Monometallic (Ni) and bimetallic (Rh-Ni and Ru-Ni) catalysts were prepared by the wetness impregnation technique of the CeO2-Al2O3 support previously synthesized by the surfactant-assisted co-precipitation method. The as-prepared powders were systematically characterized by N2-physisorption, XRD, H2-TPR, and TEM measurements to analyze their structure, morphology, and reducibility properties. Experiments were performed in a continuous fixed-bed reactor at atmospheric pressure, temperature of 800 °C, steam to carbon (S/C) ratio of 5, and WHSV of 21.15 h−1. Then, the temperature was decreased to 700 °C and increased afterwards to 800 °C. After the experiments TPO and TEM analysis were performed on the spent catalysts to check any evidence of catalyst deactivation. The results showed that the incorporation of noble metal (Ru or Rh) promoter positively affected the activity of the Ni/CeO2-Al2O3 catalysts by enhancing the reducibility of Ni2+ species. Ni-based catalyst deactivated under the studied conditions, whereas Ru- and mainly Rh-promoted systems showed increased resistance to carbon deposition by favouring the gasification of adsorbed carbon species. Between all tested catalysts, the Rh-Ni/CeO2-Al2O3 provided the highest H2 yield and coking-resistance in SR of simulated bio-oil.

Remarkable Ti-promotion in vanadium doped anatase titania for methylene blue adsorption in aqueous medium

We report here the synthesis of vanadium (5–20 at.%) doped titania and the pristine oxides via surfactant assisted coprecipitation method using cetyltrimethylammonium bromide as the surfactant and investigated their adsorption behavior towards hazardous methylene blue dye. The formation of anatase phase in all the doped materials is confirmed by the powder x-ray diffraction (P-XRD) analysis as corroborated by the Fourier transform-infrared (FT-IR) analysis, with particle sizes in the range 8–11 nm. Pure titania doesn’t show any adsorption property, but its presence enhances the adsorption property of vanadia considerably suggesting a promoting role of titania in the doped materials. The 10 at.% V-doped material, V0.1Ti0.9O2 is found to exhibit the best adsorption behaviour. The low resolution transmission electron microscopy studies reveal homogeneous nature, while ring type electron diffraction pattern suggests polycrystalline nature of the material. The high resolution transmission electron microscopy analysis suggests formation of single phase oxide. Kinetic and equilibrium studies have revealed the pseudo-second-order kinetics and Langmuir isotherm nature for this physisorption process. The pH dependency and recycling ability of this material have been discussed. Finally, X-ray photoelectron spectroscopy, FT-IR and P-XRD studies have been applied to understand the mechanism of regeneration of the material.

The Role of Neodymium in the Optimization of a Ni/CeO2 and Ni/CeZrO2 Methane Dry Reforming Catalyst

The development of a sustainable economy based on the use of renewable resources and the reduction of greenhouse gases emissions is an important mandate in modern societies to minimize the global warming. The CO2-reforming of methane through a conversion of CO2 and CH4 to syngas is a suitable process for this purpose and there is growing interest in the development of new catalysts for this process’ application at an industrial scale. This study is the first to investigate methane dry reforming activity of nickel supported on CeO2 and CeO2–ZrO2 solid solutions doped with neodymium. The supports were synthesized using a surfactant-assisted co-precipitation method and characterized through several analytical techniques to understand the role of synthesis parameters in the distribution of the dopant as well as in the properties of the supports. Co-doping with Zr and Nd resulted in an enhancement of dry reforming activity of ceria due to a higher dispersion of Ni and changes in the strength of basic sites. It was also shown that the addition of Nd helped to mitigate coking issues by increasing the mobility of surface oxygen in ceria and ceria–zirconia oxides and, accordingly, the rate of oxidation of carbonaceous deposits.

Synthesis, characterization and catalytic sorption activity of various method prepared magnetite (Fe3O4) nanoparticle deposition on porous BiMnOx nanotubes

Magnetite nanoparticle deposited porous Bi-doped MnOx nanocomposite were prepared by two step co-precipitation and deposition process. Surfactant assisted co-precipitation method is adopted to prepare porous Bi-MnOx nanotube followed by Fe3O4 nanoparticle incorporation by ultrasonic assisted deposition method. The role of iodine and EDTA for stabilize the magnetite nanoparticle have been studied. The various method prepared Fe3O4 deposited nanocomposite was characterized by X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM & TEM), Fourier transform infrared (FT-IR) spectra and Diffuse reflectance spectroscopy (DRS). XRD patterns are confirm the mixed manganese oxide and bismuth oxide phase formation. XRD and TEM study of individual magnetite nanoparticle prepared at various conditions have also been exploited. Magnetite nanoparticles are incorporated inside the tube structure of BiMnOx and also it acted as template for formation of magnetite nanorods. The nanotube morphology clearly observed using HR-TEM images. The band gap values of all prepared samples were characterized by DRS absorbance spectra. The reduce band gap values (1.97 eV–2.3 eV) are obtained for certain magnetite deposited BiMnOx nanocomposite. The as prepared sample are further tested for phenol sorption capacity and its showing enhanced adsorption capacity.

Nanostructured ZnO photocatalysts prepared via surfactant assisted Co-Precipitation method achieving enhanced photocatalytic activity for the degradation of methylene blue dyes

Zinc oxide nanopowders with different particle sizes have been successfully synthesized via co-precipitation method. Typically, X-ray diffraction (XRD) studies revealed that well crystalline single phase of ZnO nanopowders were formed with addition of surfactants (CTAB, AOT or PEG). SEM and TEM images of the formed ZnO nanopowders exhibited spherical structure either without or with addition of CTAB or PEG. Otherwise, the addition of AOT exhibited flower-like structure. UV–vis and PL spectrums privileged that the smaller the particle size led to the large band gap energy as well as the large the surface oxygen vacancies content. Consequently, the strongest the PL signal and the highest the photocatalytic activity were distinguished. Accordingly, The obtained ZnO nanopowders in the presence of CTAB as the cationic surfactant were the most effective in degrading the MB dye under ultraviolet (UV) light.

Methanol steam reforming behavior of copper impregnated over CeO2–ZrO2 derived from a surfactant assisted coprecipitation route

A series of ceria-zirconia solid solutions has been prepared by a surfactant assisted coprecipitation method. After impregnation of copper, their activities have been assessed for methanol steam reforming. The results indicate that the compositions with 10 and 15 at.% loading of copper on Ce0.6Zr0.4O2 exhibit maximum catalytic efficiency. Detailed structural analyses reveal high degree of copper dispersion on the ceria-zirconia matrix. In situ XPS studies confirm reduction of surface CuO species with concomitant lowering of Cu-surface atomic composition and increase of carbon. These evidences point to the formation of large aggregates of copper covered with coke that is suggested to be responsible for on stream activity loss. On regeneration, these aggregates break into a mixture of oxidized (Cu2+) and reduced (Cu0 and Cu+) copper species showing similar activity to the as prepared catalysts. In general, we have attributed catalytic activity to different proportions of copper components in the various forms of these catalysts.

Synthesis and Properties of Single Domain Strontium Hexa-ferrite Ultrafine Powders via a Surfactant-Assisted Co-precipitation Method

A surfactant-assisted co-precipitation method with polyethylene glycol (PEG) or cetyltrimethylammonium bromide (CTAB) as the surfactant has been used to synthesize high-quality strontium hexa-ferrite (SrM ferrite) ultrafine powders, and the influences of the surfactants on the phase formation, particle sizes and morphologies as well as the magnetic properties of the synthesized powders have been investigated. The results indicated that single phase SrM ferrite ultrafine powders with uniform particle size ranging from 150 nm to 200 nm had been synthesized with the surfactant, PEG-400 of 10 wt.%. They were characterized by a fine magnetic property with their magnetization at 1.2 Tesla of a high value about 68.0 emu/g and their coercive force of 4625Oe. Compared to CTAB and PEG-6000, the non-ionic surfactant PEG-400 with the short molecular chain was easy to attach to the surfaces of the precipitated precursors without greatly changing the co-precipitating process, and good for the dispersion of the precursors, which resulted in more uniform particle size distribution.

Synthesis and magnetic properties of (Eu–Ni) substituted Y-type hexaferrite by surfactant assisted co-precipitation method

A series of (Eu–Ni) substituted Y-type hexaferrite with composition Sr2Co(2−x)NixEuyFe(12−y)O22 (x=0.0–1, Y=0.0–0.1) were prepared by the surfactant assisted co-precipitation method. The present samples were sintered at 1050°C for 8h. The shape of the particles is plate-like which is very advantageous for various applications and the grain size varies from 73 to 269nm. The values of saturation magnetization (Ms), remanent magnetization (Mr) and magnetic moment (nB) were found to decrease which are attributed to the weakening of super exchange interactions. The values of in-plane Squareness ratios (Mr/Ms) ranging from 0.41 to 0.65 whereas in case of out of plane measurement it varies from 0.30 to 0.62.The investigated samples can be used in perpendicular recording media (PRM) due to high value of coercivity 2300Oe which is analogous to the those of M-type and W-type hard magnetic.