Simple Microemulsion Method Research Articles

Core-shell structured Ag-HAp@Bi2S3 as effective S-scheme heterojunction photocatalyst: Induced with internal polarization electric field effect and co-catalyst fashions

Considering the utilization of solar energy, the low efficiency of photocatalytic reactions is a crucial factor to take into account. One effective solution to this issue is the heterojunction method, deemed as an efficient approach for enhancing photocatalyst performance via optimal sunlight utilization. In this study, a HAp@Bi2S3 core-shell structure was synthesized using a simple microemulsion method, and subsequently, Ag nanoparticles were systematically anchored onto its surface. The Ag-HAp@Bi2S3 nanocomposite was utilized to concurrently achieve the photocatalytic degradation of Bis-phenol A (BPA) and the reduction of Cr6+ ions. The findings indicate that the heterojunction S-scheme and co-catalyst Ag have a significant role in charge separation and accelerating the photocatalytic reaction. Moreover, the presence of HAp as a polarizing substrate in this composite can create an internal polarized electric field, in addition to the electric field generated by the S-scheme heterojunction. This proposed nanocomposite exhibits potential in addressing the challenge of achieving rapid and simultaneous pollutant degradation.

Microemulsion–Assisted Synthesis of Ag2CrO4@MIL–125(Ti)–NH2 Z–Scheme Heterojunction for Visible–Light Photocatalytic Inactivation of Bacteria

Metal–organic frameworks (MOFs) are new porous materials composed of metal centers and organic ligand bridges, which received great attention in the field of photocatalysis. In this work, Ag2CrO4@MIL–125(Ti)–NH2 (denoted as AgCr@M125) Z–scheme heterojunctions were synthesized via a simple microemulsion method, by which highly dispersed nano–sized Ag2CrO4 can be anchored uniformly on the surfaces of porous MIL–125(Ti)–NH2 (denoted as M125). Compared with pure M125 and Ag2CrO4, the as–prepared AgCr@M125 hybrids show significant photocatalytic efficiency against inactivated Staphylococcus aureus (S. aureus), reaching over 97% inactivation of the bacteria after 15 min of visible light irradiation. Notably, the photocatalytic activity of the obtained 20%AgCr@M125 is about 1.75 times higher than that of AgCr–M125, which was prepared via a traditional precipitation method. The enhanced photocatalytic antibacterial activity of the AgCr@M125 photocatalytic system is strongly ascribed to a direct Z–scheme mechanism, which can be carefully discussed based on energy band positions and time–dependent electron spin response (ESR) experiments. Our work highlights a simple way to enhance the antibacterial effect by coupling with Ag2CrO4 and M125 via a microemulsion–assisted strategy and affords an ideal example for developing MOFs–based Z–scheme photocatalysts with excellent photoactivity.

A Carbon Ionic Liquid Paste Sensor Modified with Lanthanum Nanorods /MWCNTs/Nafion Hybrid Composite for Carbamazepine Screening in Biological and Pharmaceutical Media

AbstractIn this original paper, a new electrochemical sensor for carbamazepine (CBZ) was developed. First, lanthanum nanorods (LaNRs) were synthesized by a simple microemulsion method. Then, a nanocomposite consist of lanthanum nanorods, multiwalled carbon nanotubes (MWCNTs), and nafion (LaNRs/MWCNTs/Nafion) was prepared and deposited at the surface of the carbon ionic liquid paste electrode (CILPE). X‐ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersion spectroscopy (EDS), and scanning electron microscopy (SEM) were used to characterize the structure of synthesized LaNRs and the surface morphology of the modified electrode. Also, electrochemical methods such as cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) were utilized to investigate the performance of the proposed electrode. Under the optimal conditions, a linear relationship of the electrical signal versus the concentration of CBZ was obtained in the range from 0.06 μM to 20 μM with a detection limit (LOD) of 0.006 μM and quantification limit (LOQ) of 0.02 μM. Eventually, the fabricated sensor was satisfactorily applied for rapid and accurate determination of CBZ in real samples.

Microemulsion synthesis of 3D flower-like calcium zincate anode materials with superior high-rate and cycling property for advanced zinc-based batteries

A new kind of 3D hierarchical flower-like calcium zincate is successfully achieved by a simple microemulsion method. The obtained sample is constructed with many interconnected rhomboid calcium zincate nanosheets with a thickness of 80–100 nm. When served as anode active material for zinc-based battery, the as-prepared calcium zincate delivers superior high-rate properties and improved cycling stability. At 2, 5, 10, 15, 20C, the flower-like calcium zincate shows higher specific discharge capacities of ～297.7, ～254.6, ～232.5, ～202.8 and ～170.5 mAh g−1, respectively, which are significantly higher than those of the conventional hexagon and rhomboid calcium zincate. Especially, after 400 cycles at 1C/1C, the flower-like CZO achieves a capacity retention of 90.8%, whereas the values for the hexagon and rhomboid samples are only 70.2% and 54.7%, respectively. The pronounced high-rate and cycling properties are attributable to its unique 3D hierarchical flower-like structure and small particle size, which leads to the reduced charge transfer resistance, enhanced reversibility, and improved structural stability. Therefore, the proposed 3D hierarchical flower-like calcium zincate is promising anode material with excellent high-rate and cycling properties for advanced zinc-based rechargeable batteries.

Three-dimensional mesoporous dendritic fibrous nanosilica as a highly efficient DNA amplification platform for ultrasensitive detection of chlorpyrifos residues

In this paper, a novel amino-functionalized mesoporous dendritic fibrous nanosilica (NH2-DFNS) was used as DNA amplification platforms with DNA generated electrochemical signal as target conversion strategy to establish an electrochemical aptasensor for chlorpyrifos residues. The signal generation was based on the electrochemical reaction between molybdate with phosphate groups on the aptamer molecules, which greatly simplified the signal transduction and preparation steps of aptasensor, so as to improve the sensitivity of the aptasensor. The NH2-DFNS was prepared by a simple microemulsion method and characterized by SEM, TEM, FT-IR, BET, as well as XPS techniques. Importantly, the results showed that such a sphere-shaped nanomaterial with three-dimensional (3D) centerradial channels and hierarchical pores supported abundant DNA to amplify the DNA generated signal in the aptasensor. Furthermore, this aptasensor for detection of chlorpyrifos showed good sensitivity with a linear range of 1.0 fM∼1.0 nM, a detection limit of 0.43 fM. In addition, this sensor also possessed excellent specificity, repeatability, and stability. Moreover, this proposed electrochemical aptasensor was successfully used for the detection of chlorpyrifos residues in several practical samples.

A novel and simple microemulsion method for synthesis of biocompatible functionalized gold nanoparticles

Synthesize of functionalized gold nanoparticles has attracted a great deal of interest due to their favorable optical properties and broad range of biomedical applications. One challenge for biomedical application is to find a simple method in the manufacturing of biocompatible and stable water soluble gold particles with a well-controlled shape and size. In the current study, a novel methodology based on microemulsion system has been introduced to prepare biocompatible gold nanoparticles protected by a monohydroxy thioalkylated PEG ligand. The morphology and size distribution of gold nanoparticles was determined by different methods including dynamic light scattering (DLS), UV–visible spectrophotometry, Energy-dispersive X-ray analysis (EDX) and transmission electron microscopy (TEM). It is verified that the prepared water-based functionalized gold colloidal system has particles size in the range of 7–9 nm with no cytotoxicity effect to HeLa cells.

A microemulsion method for preparation of thiol-functionalized gold nanoparticles

A new microemulsion method using tetraoctylammonium bromide as a cationic surfactant has been formulated to fabricate thiol-functionalized gold nanoparticles. The nanoparticles were compared with those synthesized by the multistep Brust two-phase method. The nanoparticle sizes and size distributions fabricated by the two methods were characterized by UV–vis absorbance spectroscopy and transmittance electron microscopy. The simple microemulsion method produced the same results as those obtained by the Brust method.

Multiferroics BiMn1−xAlxO3 nanoparticles: Synthesis, characterization and evaluation of various structural, physical, electrical and dielectric parameters

The aluminium substituted bismuth based manganates with nominal composition BiMn1−xAlxO3 (x=0.0, 0.2, 0.4, 0.6 and 0.8) were prepared by the simple microemulsion method. The alteration in their structural, electrical and dielectric parameters due to Al substitution has been investigated. The X-ray diffraction analysis (XRD) confirms the formation of single phase orthorhombic with crystallite size ranges from 32 to 52nm. The morphological features and particle size were determined by using scanning electron microscopy (SEM). The dc electrical resistivity increased from 6×108 to 8×109Ωcm with the increase in substituent concentration. The dielectric constant, dielectric loss tangent and dielectric loss factor decreased with the increase in frequency. The increase in electrical resistivity makes the synthesized materials paramount over other materials and can be useful for technological applications in microwave devices.

Investigation of the structural, optical and magnetic properties of CuO/CuFe2O4 nanocomposites synthesized via simple microemulsion method

Copper oxide CuO/tetragonal CuFe2O4 nanocomposites have been synthesized via the simple microemulsion route by addition of different Fe3+ ion ratios (where Fe3+ content=0, 0.05, 0.10, 0.15 and 0.20). It is clear that the pure CuO phase was observed from the precipitated copper hydroxide precursor at pH 12 as prepared and annealed at 600 to 800°C for 2h. Meanwhile, Fe3+ addition at low substitution concentration (0.05) was indexed pure CuO phase. Further enhancing the Fe3+ up to different concentration from 0.10 to 0.20 was confirmed CuO/t-CuFe2O4 nanocomposites. The ratio of t-CuFe2O4 phase in the composite was increment with increasing the Fe3+ addition. It was increased up to 28% by addition of Fe3+ content of 0.20 and annealed at 800°C for 2h. Indeed, the crystallite size and the theoretical density calculated from XRD pattern were decreased whereas the unit cell volume was increased as the result of Fe3+-addition. The microstructures of the produced pure CuO powders were exhibited pseudo-cubic like structure whereas they were appeared as spherical like structure by addition of Fe3+ ion. Ultraviolet-visible spectrum revealed that three strong band transitions were assigned in the range of 450–950nm, characteristics to the iron substitution. Of note, the band gap energies of pure and CuO/t-CuFe2O4 powders were in the range from 1.38 to 1.47eV. Otherwise, magnetic properties evinced that pure CuO particles have weak ferromagnetic characteristics. Furthermore, the magnetic properties were enhanced with increasing the Fe3+ addition corresponding to increase t-CuFe2O4 phase content.

Room temperature synthesis of mesoporous TiO2 nanostructures with high photocatalytic efficiency

Mesoporous TiO2 nanostructures of spindle shape (diameter ∼6nm and length of 30nm) have been obtained at room temperature by a simple microemulsion method. The nanospindles are highly monodisperse with high surface area and high degree of thermostability. These TiO2 nanostructures have a high surface area (∼200m2/g) and show nearly twice the photocatalytic efficiency than of commercially available TiO2 and comparable to the best titania-based photocatalyst (TiO2 doped with expensive metals like Pt and obtained at higher temperature). There is no decrease in the efficiency of the photocatalyst even after three cycles.

TiO<sub>2</sub> Particles with Controlled Size Prepared by a Simple Micro-Emulsion Method and their Application in the Dye-Senstitized Solar Cell

Titanium dioxide was synthesized by a simple micro-emulsion method at low temperature. By using different surfactants and different mass ratios of the titanium source to the surfactant in the micro-emulsion system, we obtained the size controlled micro-structured titanium dioxide. The synthesized materials were characterized by scanning electron microscopy, and X-ray diffraction. The 10~20nm TiO2 nanoparticles are obtained by adjusting the different surfactants to control the surfactant aggregation. The highest photoelectric conversion efficiency of 7.38% was achieved in the N719-sensitized solar cells in which the nanometer-sized semiconductor TiO2 was prepared by using TritonX-100 as the surfactant and the aqueous tetrabutyl titanate (TBT) as the titanium source with the ratio of 1:4 (TritonX-100 : TBT).

Facile synthesis of fluorescent Au@SiO2 nanocomposites for application in cellular imaging

A novel fluorescent Au@SiO2 nanocomposite, with average size of ca. 30nm in the diameter, was prepared via a simple microemulsion method. Additionally, transmission electron microscopy (TEM), UV–Vis absorption spectra, Fourier transform infrared (FT-IR) spectra and fluorescence spectra were used to characterize this nanocomposite. This newly synthesized, silica-wrapped, gold nanocluster has the following advantages: good water solubility, exceptional biocompatibility, favorable surface properties and excellent fluorescence properties. Because of these advantages, a Au@SiO2 nanocomposite is exceptionally suitable for biological applications. In this study, cellular imaging, as a form of biological application, has been fully investigated, and it was discovered, after covalent conjugation of folic acid (FA), that the nanocomposite effectively recognized over expressed folic acid receptors (FARs) on the HeLa cell's surface. Therefore, this fluorescent Au@SiO2 nanocomposite could be used as a new fluorescent probe for selective biological imaging.

Optical properties and formation mechanism of radial ZnO hexagonal nanoprism clusters

Radial ZnO clusters have been synthesized in a large-scale by a simple microemulsion method using sulfonate-polystyrene (S-PS) as a template. The clusters are formed by the radial growth of ZnO hexagonal nanorods. The product is characterized by using XRD, SEM, TEM, FT-IR, and photoluminescence spectra (PL). Furthermore, the SEM images indicate that the radial ZnO structures possess hexagonal prisms structures. On the meanwhile, FT-IR spectrum reveals that S-PS is present in the radial ZnO nanostructures, and the PL spectrum shows a sharp UV emission. As a result, the formation mechanism of the radial ZnO nanostructures has been proposed.

Photoluminescence and Raman scattering of ZnO nanorods

Zinc oxide (ZnO) nanorods were synthesized by a simple microemulsion method. The photoluminescence (PL) spectra at room temperature were measured. The strong UV excitonic emission indicates the good optical properties, and the weak deep-level emission reveals very limited structural defects in the crystals. The multiple peaks in the PL spectrum obtained at 15 K are assigned to the donor-bound exciton (DBE), free to bound transition (FB) and FB–LO phonon replicas. The temperature dependence of energy, intensity, and linewidth of each emission band confirms the effect of thermal ionization progress of excitons and nonradiative recombination activated thermally. The nonresonant Raman scattering spectra at room temperature were excited by He–Ne laser (wavelength ∼632.8 nm). The perfect wurtzite structure in ZnO nanorods has been verified by the intense E 2 modes, which include low and high frequency vibrations. The possible reasons for the red shift and broadening of vibration modes were studied by the resonant Raman scattering spectra at room temperature. The power-dependence of Raman shift and FWHM shows the laser irradiation effect on the vibrational modes.

Synthesis and red-shifted photoluminescence of single-crystalline ZnO nanowires

Local-oriented single-crystalline ZnO nanowires have been synthesized in large scale by a simple microemulsion method in the presence of sulfonate-polystyrene (S-PS) and dodecyl benzene sulfonic acid sodium salt (DBS). The as-prepared product is characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), infrared (IR) spectra and photoluminescence (PL) spectrum. The nanowires exhibit a local congregation and preferentially grow along the [0 0 2] facet. FT-IR spectrum indicates that S-PS is adsorbed on the surface of ZnO nanowires. The PL spectrum shows evidently red-shifted ultraviolet (UV) emission.