Surfactant-assisted Method Research Articles

Surfactant-assisted synthesis of copper oxide nanorods for the enhanced photocatalytic degradation of Reactive Black 5 dye in wastewater.

In this study, copper oxide nanorods were synthesized via surfactant-assisted chemical precipitation method and characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and UV-Visible spectrometer. XRD result reveals that CuO nanorods were structured in the monoclinic phase. SEM image suggested that synthesized CuO were shaped like nanorod with approximately 20-40nm width and 500-800nm length. The observed band gap calculated from UV-Visible absorption studies is 1.45eV. As-prepared CuO nanorods were applied as a photocatalyst for the degradation of textile dye Reactive Black 5 (RB-5) in aqueous solution under the presence of visible light. The result exhibited that an enhanced degradation of RB-5 was achieved around 98% within 300min and the experimental values were well matched with the linear fit model (R2 = 0.97) and the observed rate constant found to be 5 × 10-3min-1. Therefore, as-synthesized CuO nanorods can be applied as a potential photocatalyst material for the degradation of organic pollutants in the wastewater.

Efficient degradation of tetracycline in aqueous solution by Ag/AgBr catalyst under solar irradiation

To enhance the catalytic degradation efficiency of tetracycline (TC) in aqueous solution under solar irradiation, novel Ag/AgBr catalyst was prepared by surfactant assisted method, where an oil/water microemulsion was employed as synthesis medium. The Ag/AgBr catalyst was characterized by diverse techniques, such as SEM, XRD, XPS, BET, and DRS. Under sunlight irradiation, Ag/AgBr showed high photocatalytic capacity on TC degradation. To better understand the degradation mechanism, the important factors that affect the photocatalytic performance of TC were studied and optimized. The optimum conditions were 0.20 g L−1 of Ag/AgBr, 30 mg L−1 for TC, and pH of 11, respectively. The photodegradation kinetics of TC by Ag/AgBr catalyst complied with pseudo-first-order model. Based on our experimental facts, a possible photodegradation mechanism of Ag/AgBr has been proposed. Chemical oxygen demand (COD) could be decreased to approximate 99% under optimum experimental condition. Moreover, Ag/AgBr photocatalyst had good reuse performance for degrading TC. The obtained results show that the excellent photocatalytic capability of Ag/AgBr makes it feasible to utilize solar irradiation to degrade TC in solution.

Electrospinning of highly dispersed Ni/CoO carbon nanofiber and its application in glucose electrochemical sensor

In this work, a common anionic surfactant SDS was used as one of a precursor, combining anionic surfactant-assisted equilibrium adsorption method and electrospinning method to fabricate highly dispersed Ni/CoO loaded carbon nanofiber. Through this approach, Ni/CoO can uniformly in-situ grow on the surface of the carbon nanofiber. Compared with the hydrothermal method, this method is more simple and stronger. Thus, the as prepared Ni-CoO/CNF exhibits an excellent catalytic activity and sensitivity for determination of glucose. Furthermore, we investigated the effect of different amounts of surfactants on the morphology of the material and its effect on the glucose current response. Under optimal conditions, Ni-CoO/CNF showed a good linear range from 0.25 μΜ to 600 μΜ and an extremely low detection limit of 0.03 μΜ, which make it possible for determination of samples with low glucose concentration.

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.

Synthesis and Characterization of Nanostructured Copper Zinc Tin Sulphide (CZTS) for Humidity Sensing Applications

Copper zinc tin sulphide (CZTS) microsphere comprising thin nano sheets with high porosity and the wide surface area was developed via the surfactant-assisted hydrothermal method and was further characterized using XRD, FESEM, and TEM revealing its crystalline nature, efficient morphology, and internal structural, respectively. The band gap of CZTS is found to be 1.8 eV owing minimum crystallite size and the average crystallite size of 13 and 34 nm, respectively. The absorption analysis of CZTS was done using UV-Vis, FTIR, and Raman spectroscopy. Finally, the humidity sensing capability of the material was enquired using both the electrical and optical modes. Electrical mode gave an excellent sensitivity of 10.77 MΩ/%RH with the fast response and recovery times of 7.4 and 57 s, respectively, whereas optical mode gave a sensitivity of ~1.051 μW/%RH with the response and recovery times of 46 and 80 s, respectively.

Application of a new sample preparation method based on surfactant-assisted dispersive micro solid phase extraction coupled with ultrasonic power for easy and fast simultaneous preconcentration of toluene and xylene biomarkers from human urine samples

A fast and easy surfactant-assisted dispersive micro-solid phase extraction method coupled with ultrasonic power was used for the simultaneous preconcentration and determination of low levels of hippuric and methyl hippuric acid in human urine samples. In the first step, magnetic nanoparticles was coated by titanium oxide nanoparticles (Fe3O4/TiO2 NPs), afterward characterized by the scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. In the next step, anionic surfactants were thus combined with the synthesized magnetic nanoparticles to create a new adsorbent for increasing the simultaneous extraction of hippuric and methyl hippuric acid. After elution of extracted target molecules by the sorbent, the concentration of these molecules were measured by high-performance liquid chromatography (HPLC–UV). Meanwhile, a statistical approach known as Box–Behnken design was applied for optimizing significant parameters. With the optimum parameters anticipated by the experimental design, the limit of quantification (LOQ) acquired was reported to be 3 µg L− 1, and the calibration curve was linear within the concentrations of 3–1000 µg L− 1. Finally, the method was effectively implemented for the determination of low levels of hippuric and methyl hippuric acid in human urine samples.

Targeting inside charge carriers transfer of photocatalyst: Selective deposition of Ag2O on BiVO4 with enhanced UV–vis-NIR photocatalytic oxidation activity

Rational regulation of photogenerated carrier separation and transfer is a significant strategy to optimize the photocatalytic activity. Given that the synergistic effect of crystal-face engineering and interfacial heterojunction modification, selective deposition of Ag2O nanoparticles onto BiVO4 (040) facet has been realized successfully via the surfactant-assisted hydrothermal method combined with a facile coprecipitation process. As expected, compared to pure BiVO4 and Ag2O, BiVO4 (040)/Ag2O heterostructures have revealed great enhancements in photocatalytic O2 evolution and methylene blue (MB) degradation capacities no matter under UV, Vis or NIR light irradiation. In-depth investigations confirm that the pronounced photooxidation performances are attributed to not only the outstanding capability in harvesting photon energies spanning from ultraviolet (UV) to near-infrared (NIR) regions, but also the accelerated charge carrier separation boosted by the charge density redistribution inside the BiVO4 homojunction.

Composite Material that Comprised Metal-Organic Nanotubes and a Sponge as a High-Performance Adsorbent for the Extraction of Pharmaceuticals and Personal Care Products from Environmental Water Samples.

A composite material that comprised metal-organic nanotubes (MONTs) and a sponge, Cu-MONTs-sponge, was synthesized by using a rapid and convenient surfactant-assisted dip-coating method and used as a high-performance adsorbent for the solid-phase extraction of pharmaceuticals and personal care products (PPCP) from environmental water samples. By adjusting the surfactant concentration, a composite material that contained metal-organic nanotubes and a macroporous 3D porous sponge was constructed. This modified sponge achieved outstanding reproducibility as an adsorbent, with the adsorption of trace or ultratrace amounts of contaminants. Moreover, this composite material was conveniently recycled and its extraction efficiency only decreased by 6.3-12.1 % after 30 adsorption/desorption cycles. The resulting composite exhibited excellent adsorption capacity for PPCPs, which was attributed to its unique porous structure, natural hydrophobicity, and electrostatic interactions between the metal-organic nanotubes and analyte molecules. This Cu-MONTs-sponge material is an ideal adsorbent for the extraction of trace amounts of PPCPs from environmental water samples.

Surfactant-assisted synthesis of ultrathin two-dimensional Co3O4 nanosheets for applications in lithium-ion batteries and ultraviolet photodetector

Ultrathin two-dimensional (2D) Co3O4 nanosheets were prepared by surfactant-assisted self-assembly method. We demonstrate a high reversible capacity and an excellent rate capability of ultrathin 2D Co3O4 nanosheets as anodes in Li ion batteries. At a current density of 100 mA g−1, the nanosheets maintain an extraordinary capacity of 1868.6 mA h g−1 after 30 discharge/charge cycles, and nearly 100% capacity retention. When the current is increased to 400 mA g−1, 112% of the capacity can be retained. With their ease of large area synthesis and superior electrochemical properties, the 2D Co3O4 nanosheets will be interesting for practical Li ion batteries. Additionally, 2D Co3O4 nanosheets also showed both high stability and reproducibility as ultraviolet photodetector.

A simple strategy to prepare polyaniline nanorods by surfactant-assisted electropolymerization for remarkably improved supercapacitive performances

Abstract This work reports on the significant improvement of electrochemical capacitive properties of the polyaniline (PANI) electrode via morphology changes, following an efficient and simple route. Specifically, a surfactant-assisted electropolymerization method is put forward to prepare PANI nanorods (PNRs) electrode and the formation mechanism of PNRs is investigated. In comparison to PANI electrode with compact microstructures, PNRs electrode has a dispersed nanorod-shaped morphology, showing substantially improved supercapacitive performances. The resulting PNRs electrode has the high areal capacitance of 345.9 mF cm−2, which represents a boost of as much as 40% comparing with that of PANI electrode. The PNRs electrode also features superior rate performance and excellent cycling stability, exhibiting 93.1% of capacitance retention after 10000 cycles. The present study has demonstrated a new and simple strategy to prepare nanostructured PANI and the prepared PNRs supercapacitor electrode is very promising for practical applications.

Overview on the use of surfactants for the preparation of porous carbon materials by the sol-gel method: applications in energy systems

Abstract Porous carbon materials attract great interest because of the wide range of applications in electrochemical energy systems, especially in the case of structured and porosity-tuned carbons prepared by template-assisted methods. The use of surfactant prevents the collapse of the porous structure during the air-drying stage in the sol-gel process, which is regarded as a critical stage in this method. This work offers an overview on the use of surfactants as templates for the manufacture of tunable porous carbon materials by the sol-gel method mainly using the polymerization reaction of resorcinol (R) and formaldehyde (F). The use of surfactants avoids the application of other economically disadvantaged drying techniques such as supercritical fluids and freeze-drying. The surfactant-assisted sol-gel methods reported in the literature for the fabrication of porous carbons are widely discussed, as well as the potentiality of the synthesized materials as electrodes in electrochemical systems, which greatly depends on the final porous structure. Besides, this work offers information on hybrid methods in which surfactants are used not only for the fabrication of porous carbon materials with mesoporous/microporous structure but also for the development of advanced structures and composites, including nanomaterials with enhanced properties. Finally, future prospects in the synthesis of carbon materials prepared by surfactant-assisted sol-gel method are presented.

Fabrication, characterization, and luminescent properties of Y2WO6: Gd3+, Dy3+ hierarchical microspheres

A series of monodisperse Y2WO6: Dy3+, Gd3+ hierarchical microspheres were synthesized via a facile surfactant-assisted hydrothermal method followed by heat treatment. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and photoluminescence (PL) spectra. XRD patterns of the samples with Gd3+ codoping exhibit a merging of (− 232) and (232) peaks, indicating the distorted deformation in Y2WO6 host structure. SEM images demonstrate that the Y2WO6: Dy3+, Gd3+ microspheres are well-dispersed and assembled by many irregular nanoparticles. Upon ultraviolet (UV) excitation at 291 nm, the emission peaks of Dy3+ ions is observed at 480 nm (blue), 579 nm (yellow) and 669 nm (red), corresponding to the characteristic transitions of 4F9/2 → 6H15/2, 4F9/2 → 6H13/2 and 4F9/2 → 6H11/2 of Dy3+, respectively. The optimal PL intensity was obtained in Y2WO6: 2.5 mol% Dy3+ microspheres which can be further enhanced with the codoping of Gd3+. The strongest luminescence is achieved at Gd3+ concentration of 40 mol% with a quantum yied (QY) of 34.45%. In addition, the thermal stability of the sample was also investigated. The CIE of the investigated samples exhibit little change by varying the concentration of Gd3+ ions. The calculated CIE values are all around (0.37, 0.38) and located at the white region, suggesting that the Y2WO6: Dy3+, Gd3+ microspheres could be used for white LEDs.

Simultaneous fluorometric determination of the DNAs of Salmonella enterica, Listeria monocytogenes and Vibrio parahemolyticus by using an ultrathin metal-organic framework (type Cu-TCPP).

Ultrathin (<10nm) nanosheets of a metal-organic framework (MOF-NSs) were prepared in high-yield and scalable production by a surfactant-assisted one-step method. The MOF-NSs possess distinguished affinity for ssDNA but not for dsDNA. This causes the fluorescence of the labeled DNA to be quenched. On binding to the target DNA (shown here for Salmonella enterica, Listeria monocytogenes and Vibrio parahemolyticus), the labeled duplex is released and the fluorescence of the label is restored. The labels Texas Red, Cy3 and FAM were used and give red, red or green fluorescence depending on the kind of pathogen. The detection limits are 28 pM, 35 pM and 15 pM for the gene segments of Salmonella enterica, Listeria monocytogenes and Vibrio parahemolyticus, respectively. Graphical abstract Schematic of an ultrasensitive fluorescent biosensor for multiplex detection of pathogenic DNAs based on ultrathin MOF nanosheets (type Cu-TCPP).

Lead-free silver-antimony halide double perovskite quantum dots with superior blue photoluminescence.

Novel all-inorganic Sb-based lead-free double perovskite Cs2AgSbX6 (X = Cl, Br or I) quantum dots exhibiting excellent air stability and strong blue emission with photoluminescence quantum yields of 31.33% were synthesized for the first time using a surfactant-assisted method. The ligand, oleic acid, could control the crystallization of the pure perovskite phase and significantly passivate the surface.

Fulvic Acid Reduced GO and Phthalocyanine Nanorods as Reaction Platform for Simultaneous Determination of Catechol, Hydroquinone, Phenol and p-nitrophenol

In this paper, a novel nanocomposite fulvic acid reduced graphene oxide (FA-rGO) and Co-phthalocyanine nanorods (CoPcNRs) was prepared and used to construct an electrochemical sensor for simultaneous detection of catechol (CC), hydroquinone (HQ), phenol (PN) and p-nitrophenol (p-NP). FA as reductant used to prepare FA-rGO nanocomposite, which fabricated by hydrothermal method and freeze-drying process. The method is environmentally friendly and realizes the gentle reduction of GO. CoPcNRs were synthesized by surfactant-assisted ultrasonic method. The microstructure and morphologies of the as-prepared materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-Vis spectrophotometer. The electrochemical oxidation of CC, HQ, PN and p-NP was investigated using differential pulse voltammetry (DPV). The results show that the FA-rGO/CoPcNRs modified electrode exhibits excellent electrochemical activity toward the simultaneous redox of CC, HQ, PN and p-NP. Under optimal conditions, the linear ranges of CC, HQ, PN and p-NP were 1 μM–650 μM, 2 μM–450 μM, 2 μM–160 μM, 2 μM–140 μM, with 0.3 μM, 0.65 μM, 0.65 μM and 0.65 μM, respectively. In addition, the modified electrode showed good selectivity, sensitivity and stability. The application in real samples was also evaluated, and the recoveries suggesting that FA-rGO/CoPcNRs nanocomposites could be used as an excellent potential reaction platform for the simultaneous determination of CC, HQ, PN and p-NP in environmental samples.

Surfactant-assisted synthesis and electrochemical properties of an unprecedented polyoxometalate-based metal-organic nanocaged framework.

The first polyoxometalate (POM)-containing nanocage based metal-organic framework (Zn-POMCF) was synthesized by a surfactant-assisted method. In contrast to the Zn-based metal-organic framework (Zn-MOF), the cooperative assembly of POM and a Zn/trz macrocycle gave rise to high stability and good electrochemical ability of the Zn-POMCF in lithium-ion batteries (LIBs).

Novel defect-fluorite pyrochlore sodium niobate nanoparticles: solution-phase synthesis and radiation tolerance analysis.

Materials possessing a defect-fluorite pyrochlore structure can have a range of useful properties that are sought after, which include their radiation tolerance, nuclear waste immobilization, and phase stability at elevated temperatures. In this study, we demonstrate for the first time the synthesis and a detailed analysis of defect-fluorite pyrochlore sodium niobate (NaNbO3) nanoparticles. This analysis included an investigation into their stability to elevated temperatures and neutron irradiation. A surfactant-assisted solvothermal method is used to prepare nanoparticles of NaNbO3. This solution-phase approach results in the formation of crystalline nanoparticles of a defect-fluorite pyrochlore NaNbO3 at relatively low temperatures. The products had an average diameter of ∼74 ± 11 nm. The nanoparticles adopted a defect-fluorite pyrochlore phase and matched the cubic Fm3[combining macron]m space group. This pyrochlore form of NaNbO3 was found to be stable up to 500 °C. The nanoparticles transformed into the orthorhombic and rhombohedral perovskite phases of NaNbO3 along with the introduction of a pseudo-hexagonal Nb2O5 at higher temperatures. These defect-fluorite pyrochlore nanoparticles of NaNbO3 also exhibited a resistance to radiation induced amorphization. The dimensions, phase, and crystallinity of the defect-fluorite pyrochlore nanoparticles after exposure to a flux of neutrons were comparable to those of the as-synthesized product. The thermal stability and radiation tolerance of these pyrochlore nanoparticles could be useful in the design of thermally resilient materials, high temperature catalysts, and durable materials for the handling and storage of radioactive waste.

Enhancing the cycle life of Li-S batteries by designing a free-standing cathode with excellent flexible, conductive, and catalytic properties

Poor electrical conductivity of sulfur, sluggish redox kinetics, dissolution of intermediate polysulfides, and expansion in volume upon cycling are the main drawbacks that hamper the practical application of Li-S batteries. By taking advantages of the high conductivity and favorable catalytic activity of RuO2, we design a 3D carbon nanotube film with embedded RuO2 nanoparticles as a freestanding type of chemisorptive and catalyst-like cathode for Li-S batteries, which can be facilely prepared by a surfactant-assisted vacuum infiltration method. Both experimental and theoretical results reveal the excellent capability of RuO2 for anchoring polysulfides and accelerating the kinetics of polysulfides catalytic redox reactions. Besides, the 3D freestanding cathode is beneficial to overcoming pulverization during volume changes, especially for long-term cycling. At a high areal sulfur loading of 2 mg cm−2, favorable initial capacities of 750 and 1060 mA h g−1 respectively at 2 and 0.5 C are achieved. More attractively, the capacity after 1000 cycles maintains 405 mA h g−1 at 0.5 C with a loss in capacity of only 0.06% per cycle. Additionally, such freestanding cathode allows the batteries to be tested under various bending stages, hence encouraging more research works on fabrication of other 3D nanostructure families as high-performance cathodes for Li-S batteries.

Synthesis of hollow carbon spheres from polydopamine for electric double layered capacitors application

This paper reports a surfactant-assisted template method for synthesis of hollow carbon nanospheres by using polydopamine (PDA) as carbon source and ZnO as template. In the help of surfactant micelles, spherical ZnO particles are firstly formed and then coated with PDA films at room temperature without structure damage by the alkaline conditions needed for self-polymerization of dopamine. After carbonization in N2 atmosphere followed by ZnO removal, hollow carbon spheres with adjustable particle size (150–300 nm), high specific surface area (SSA, ~1100 m2 g−1) and optimized mesopore size distribution are obtained. The effects of surfactant content and carbonization temperature on the morphology and the electrochemical properties of the as-prepared carbons have been further investigated. The hollow carbon spheres obtained at optimum synthetic conditions exhibit outstanding electrochemical properties including high capacitance (156 F g−1 at 2 mV s−1) and rate capability (125 F g−1 even at 200 mV s−1) as well as cycling stability with 98% capacitive retention after 16,000 cycles, suggesting that it is a promising electrode material for the application of electric double layered capacitors.

Hydration accelerator and photocatalyst of nanotitanium dioxide synthesized via surfactant-assisted method in cement mortar

To develop TiO2-based cement materials, the effect of TiO2 on the cement hydration and photocatalytic reaction should be investigated. The phase, size and shape of TiO2 are important factors for better understanding its application in cement. TiO2 nanoparticles were synthesized by a surfactant-assisted, reverse micelle method to control phase, size and shape by three selected surfactants namely: sodium dodecyl sulfate (SDS), cetyl trimethylammonium bromide (CTAB) and TritonX-100. The synthesized TiO2 nanoparticles were characterized by XRD, SEM and TEM for observation of phase, size and shape. The modified micro structures of admixed cements with the different synthesized TiO2 nanoparticles incorporated were also examined by SEM. Particularly, the hydration process and photocatalytic reaction of the cement mixture were evaluated by heat flow calorimetry and methylene blue (MB) degradation, respectively. Results showed that anatase-rich and smaller size TiO2 nanoparticles provided accelerated cement hydration and the ability to degrade MB photocatalytically at the surface of admixed-TiO2 cement.