Salt-assisted Ultrasonic Spray Pyrolysis Research Articles

Highly efficient Au/Fe2O3 for CO oxidation: The vital role of spongy Fe2O3 toward high catalytic activity and stability

Supported gold catalysts have drawn great attention for many decades due to their outstanding performance in remedying the environment from carbon monoxide (CO) pollution. In this study, due to the large surface area of spongy Fe2O3, fabricated by salt-assisted ultrasonic spray pyrolysis, a considerable amount of Au was loaded on spongy Fe2O3 compared to low-surface-area non-spongy Fe2O3. It is seen that the spongy Fe2O3 catalyst loaded with Au has an interface that can be extremely active for CO desorption and O2 activation. That means it has high catalytic activity in CO oxidation than non-spongy and low surface area Fe2O3 loaded with Au. Also, the incorporation of Au in low alkaline condition further enhances the interaction between Au and Fe2O3, providing more active sites. This made the catalyst to have better activity, good stability over 60 hrs, and there was no carbonate on its surface. It had full conversion at 30 °C on 120 L g-1h−1 with high TOF (2.2 s−1).

Effect of Pyrolysis temperature on TiO<sub>2</sub> Nanoparticles Synthesized by a Salt-assisted Ultrasonic Spray Pyrolysis Process

Effect of Pyrolysis temperature on TiO<sub>2</sub> Nanoparticles Synthesized by a Salt-assisted Ultrasonic Spray Pyrolysis Process

Synthesis and magnetic properties of Sm2Co17 particles using salt-assisted spray pyrolysis and a reduction-diffusion process

Sm2Co17 particles, with several hundreds of nanometers to a few micrometers in diameter, were synthesized by a combination of salt-assisted ultrasonic spray pyrolysis and a reduction-diffusion (R-D) process. It was found that NaCl plays a decisive role toward the suppression of particle coalescence during R-D process. By optimizing a reductant contents, the single-phased and non-agglomerated Sm2Co17 particles were obtained. In addition, particle size was controlled by varying calcination temperature from 800 °C to 1100 °C and size-dependent magnetic properties were observed. The optimum magnetic properties were achieved at a calcination temperature of 900 °C: coercivity of 5.3 kOe, a saturation magnetization of 99.33 emu/g, and a remanence of 56.53 emu/g.

Facile synthesis of zirconia nanoparticles using a salt-assisted ultrasonic spray pyrolysis combined with a citrate precursor method

Current synthesis processes for zirconia nanoparticles require expensive precursors or templates, complex steps and long reaction times, and produce highly agglomerated nanoparticles. In this study, we demonstrated a simple and continuous approach for synthesizing zirconia nanoparticles by combining a salt-assisted ultrasonic spray pyrolysis with a citrate precursor method. This process allows tuning of the morphology and size, where hollow sub-micron particles are transformed to minute nanoparticles by controlling (through a chelating reaction) the diffusion rate of zirconium cations in a pyrolysis step. The synthesized nanoparticles (average diameter: ∼10 nm) are characterized by a highly crystalline tetragonal structure, uniform particle-size distribution, and high specific surface area. A detailed mechanism for generating tiny nanoparticles, via this process, is presented and the optical properties of the nanoparticles are evaluated through an ultraviolet–visible (UV–vis) diffuse reflectance spectrum and converted Kubelka-Munk function.

Synthesis and Optical Property of BaTiO3 Nanoparticles Using a Salt-assisted Ultrasonic Spray Pyrolysis Process

Synthesis and Optical Property of BaTiO3 Nanoparticles Using a Salt-assisted Ultrasonic Spray Pyrolysis Process

Synthesis of Single Crystalline Titanium Oxide and Sodium Titanate Nanorods Via Salt-Assisted Ultrasonic Spray Pyrolysis

AbstractThe simple and continuous synthesis of single crystalline anatase titanium dioxide and sodium titanate nanorods by a salt-assisted ultrasonic spray pyrolysis method is demonstrated. This method does not require expensive precursors, long reaction time, and physical templates or surfactant. In addition, its continuous nature makes it a suitable method for the large-scale preparation. Moreover, the effect of a salt concentration in a starting solution on material properties, including morphology and phase of the synthesized products was systematically investigated. The synthesized nanorods had one-dimensionality, a single crystalline and the average diameter of 12.3 nm with dual phases of titanium dioxide and sodium titanate by FE-SEM, XRD, HR-TEM as well as FFT-converted SAED pattern analysis.

Synthesis and Photoluminescence Properties of ZrO2:Eu3+ Nanoparticles Using Salt-Assisted Ultrasonic Pyrolysis Process

Inorganic phosphors based on ZrO2:Eu3+ nanoparticles were synthesized by a salt-assisted ultrasonic spray pyrolysis process that is suitable for industrially-scalable production because of its continuous nature and because it does not require expensive precursors, long reaction time, physical templates or surfactant. This facile process results in the formation of tiny, highly crystalline spherical nanoparticles without hard agglomeration. The powder X-ray diffraction patterns of the ZrO2:Eu3+ (1-20 mol%) confirmed the body centered tetragonal phase. The average particle size, estimated from the Scherrer equation and from TEM images, was found to be approximately 11 nm. Photoluminescence (PL) emission was recorded under 266 nm excitation and shows an intense emission peak at 607 nm, along with other emission peaks at 580, 592 and 632 nm which are indicated in red.

Synthesis and magnetic properties of La3+-Co2+ substituted strontium ferrite particles using modified spray pyrolysis–calcination method

The purpose of the research was to improve the intrinsic magnetic properties of strontium ferrite by substituting lanthanum and cobalt for strontium and iron. The salt-assisted ultrasonic spray pyrolysis (SA-USP) following calcination process were used to from La-Co substituted strontium ferrite particles (LaxSr1-xFe12-yCoyO19), and their compositional dependent magnetic properties systemically investigated. All the samples were calcined at 1050°C for 1h in an air atmosphere to yield single-phased hexagonal particles several hundred nanometers to microns in size. A saturation magnetization of 70.76emu/g and a coercivity 7265Oe were obtained at a composition of La0.25Sr0.75Fe11.75Co0.25O19. The amount of Co was reduced to obtain an optimized saturation magnetization of 71.40emu/g and a coercivity of 7572Oe at a composition of La0.25Sr0.75Fe11.8Co0.2O19.

Effects of Different Salts on Salt-Assisted Ultrasonic Spray Pyrolysis (SA-USP) Calcination for the Synthesis of Strontium Ferrite.

Strontium ferrite (hexaferrite), SrFe12O19, was successfully fabricated in sizes ranging from hundreds of nanometers to several micrometers by salt-assisted ultrasonic spray pyrolysis-calcination using different salt media. All samples were single phases of SrFe12O19 without the intermediate phase, α-Fe2O3, and their morphology was hexagonal. As calcination temperature increased, the size of as-calcined samples and saturation magnetization, Ms, increased while coercivity decreased. The particle size of the obtained nanoparticles varied depending on the salt media and calcination temperatures. The best magnetic properties obtained in this experiment were a coercivity of 6973 Oe with a saturation magnetization of 68.3 emu/g. To the best of our knowledge, these coercivity values are the highest ever obtained. We propose a detailed mechanism explaining the growth of these particles and conclude that the resulting single-domain particle size is about 70 nm, taking into account of factors affecting coercivity in ferrite nano- to micro-sized particles.

Metallic alloy nanoparticle-based fabrication and optical properties of a Cu(In1−xGax)S2 absorber layer for solar cells

A highly-densified Cu(In1−xGax)S2 (CIGS2) absorber layer was fabricated using copper, indium and gallium (CIG) metallic alloy nanoparticles synthesized by salt-assisted ultrasonic spray pyrolysis (SAUSP) followed by direct thermal reduction. The reduction process in salt matrix minimized aggregation of CIG metallic alloy nanoparticles that have the potential to lead to higher film densification during sulfurization. To optimize the amount of salt, various NaCl/precursor ratios were used for SAUSP and Cu–In metallic alloy nanoparticles with average particle size of 79nm were obtained. The CIGS2 obtained in the present study exhibited a variable band-gap ranging from 1.46 to 2.4eV depending on the Ga/(In+Ga) ratio, which corresponded to the respective bulk materials.

Synthesis of Size-Controlled SrFe12O19 Using Modified Spray Pyrolysis–Calcination Method and Their Magnetic Properties

Strontium hexaferrite (SrFe12O19, SrM) suitable for high-performance permanent magnet applications was synthesized by salt-assisted ultrasonic spray pyrolysis (SA-USP) and subsequent calcination. To control the particle size, the intermediate phase of SrM was collected by SA-USP and various sizes of SrM were obtained by calcining the as-prepared sample at temperatures ranging from 800°C to 1050°C. The synthesized SrM was magnetically aligned by using an external magnetic field to improve remanence. The synthesized particles were of nano- to submicron scale and nonagglomerated. The magnetic properties and squareness of the material depended on the particle size and distribution. Additionally, the NaCl added during synthesis facilitated the formation of nonagglomerated particles, while enhancing and controlling particle growth. The optimum magnetic properties were achieved at calcination temperature of 1000°C, resulting in coercivity of 5646 Oe, saturation magnetization of 73.3 emu/g, and remanence of 59.1 emu/g (80.6% of Ms).

Synthesis and Magnetic Properties of Aligned Strontium Ferrites

Reducing the particle size of hexagonal ferrites is known to increase their coercivity effectively. However, the size reduction also enhances the agglomeration that deteriorates the magnetic alignment of these particles. In this paper, hexagonal plate shape strontium ferrite particles with an average size of 700 nm using a facile salt-assisted ultrasonic spray pyrolysis method were synthesized to increase the coercivity and prevent the agglomeration during calcinations process. Sodium chloride (NaCl) was used as a salt, and the reacted powders were sintered at 1050 $^{\circ}{\rm C}$ for 2 h under various oxygen flow rates. With increasing the flow rate of oxygen, the specific saturation magnetization of synthesized strontium ferrite particles increased from 62 to 71 emu/g and the coercivity reached 6000 Oe. Strontium ferrite particles aligned under a magnetic field of about 10 kOe showed that the remanence was 91.85%.

Barium hexaferrite nanoparticles with high magnetic properties by salt-assisted ultrasonic spray pyrolysis

Herein, we synthesized non-agglomerated barium hexaferrite nanoparticles by salt-assisted ultrasonic spray pyrolysis at different reaction temperatures. NaCl was used as an added salt, melted at 850, 900, and 950 °C to act as a solvent in the reaction processes. It was found that at 950 °C, the salt melted sufficiently and therefore accelerated the subsequent nucleation and growth of barium hexaferrite nanoparticles. The barium hexaferrite nanoparticles synthesized by the salt-assisted ultrasonic spray pyrolysis method were exquisitely compared with the barium hexaferrite synthesized by conventional ultrasonic spray pyrolysis method. The particles were characterized by XRD, SEM, and TEM analyses. The salt-free barium hexaferrite obtained at 950 °C revealed the presence of hematite, whereas the salt-added barium hexaferrite nanoparticles synthesized at 950 °C showed the existence of only barium hexaferrite phase. The salt-added barium hexaferrite nanoparticles synthesized at 950 °C showed a hexagonal plate shape, 72 nm in size and with good crystallinity. The magnetic properties were investigated by vibrating sample magnetometer (VSM) at room temperature. The magnetic properties of the salt added barium hexaferrite at 950 °C showed the coercivity of 5735 Oe and saturation magnetization of 63.2 emu/g.

Oxide nanoparticle-based fabrication and optical properties of Cu(In1 − xGax)S2 absorber layer for solar cells

The compound Cu(In1−xGax)S2 (CIGS) was synthesized using copper oxide, indium oxide and gallium oxide mixture (CIGO) nanoparticles using salt-assisted ultrasonic spray pyrolysis (SAUSP). Under this method, CIGS can be produced without the complicated restrictions of a vacuum and an inert atmosphere. The band gap of CIGS can be controlled by introducing the desired stoichiometric quantities of starting materials. In order to synthesize CIGO nanoparticles, various NaCl/precursor ratios were used to accomplish the SAUSP process and ultimately monodisperse CIGO nanoparticles with average particle size of 9nm without hard agglomeration were obtained. Subsequently, the CIGO nanoparticles were sulfurized to form the CIGS in H2S/Ar atmosphere at 500°C. The CIGS obtained in the present study has the various band gap ranging from 1.67 to 2.34eV depending on the Ga/(In+Ga) ratio, and those band gap correspond to the respective bulk materials.

Preparation of Calcium-Phosphate Microspheres by Salt-Assisted Ultrasonic Spray-Pyrolysis Technique and their Drug Release Behavior Using Anti-Angiogenic Agent, TNP-470

Synthetic clcium phosphate based materials, such as hydroxyapatite (Ca10(PO4)6(OH)2; HAp) and tricalcium phosphate (Ca3(PO4)2; TCP), are compounds with high potential for clinical applications to orthopedic and dental region. In previous study, we have reported that the hollow and porous apatite microsphere could be prepared by salt-assisted ultrasonic spray-pyrolysis (SAUSP) technique using sodium chloride (NaCl). In this case, these microspheres have some problems of (i) decrease of dissolubility of microspheres and (ii) cytotoxicity arising from chloride ions elution. To overcome these disadvantages, we prepared novel microspheres by SAUSP technique using potassium nitrate (KNO3) instead of NaCl. The resulting microsphere was washed with pure water to remove the KNO3 phase. The particle shapes of the powders were observed by scanning electron microscopy (SEM); the diameters of the microspheres were of 0.5 - 3.0 m, and the fine pores with the sizes of ~50 nm were present on the surface of the microspheres. The TNP-470 agent as a model of drug were loaded on these microspheres with nano-pores in the surface. In the KNO3 concentration of 1.00 mol·dm-3, 70 % of the total TNP-470 from the microspheres was rapidly released within 1 h. The remaining 30 % was slowly released up to 24 h following immersion, and total amount of TNP-470 released from the microspheres was 42 g·mg-1.