One-step Ultrasonic Spray Pyrolysis Research Articles

A novel copper-doped porous carbon nanospheres film prepared by one-step ultrasonic spray pyrolytic of sugar for photocatalytic degradation of methyl orange

Copper-doped porous carbon nanospheres film (Cu@PCNF) was prepared via one-step ultrasonic spray pyrolysis (USP) for photocatalytic degradation of methyl orange (MO). The photocatalytic degradation rate reached 80% after 4 h under sunlight, and kinetic simulation results showed that the degradation reaction was a first-order reaction. Furthermore, the degradation rate did not decrease significantly after eight experiment cycles, which indicated that the film had good reusability and durability. This film synthesis technology provided a simple and effective strategy for improving the photocatalytic performance of contaminant treatment materials.

Characterization of CeO2 microspheres fabricated by an ultrasonic spray pyrolysis method

CeO2 is one of the main catalysts for solid oxide fuel cell (SOFC). It is critical to find a green and cost-effective fabrication method for CeO2 at scale. In this study, the CeO2 microspheres were prepared by one-step ultrasonic spray pyrolysis of cerium chloride solution at 700 °C. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) study demonstrate that the prepared CeO2 microspheres exhibit a particle size of 0.01–1.08 μm with a mean particle size of 0.23 μm, and more than 94% of the particles have a diameter less than 0.5 μm. But the presence of residual Cl in the fabricated CeO2 microspheres blocks the active sites and leads to the significant degradation of SOFC performance. The formation mechanism and distribution of residual Cl in the fabricated CeO2 microspheres were systemically studied. The water washing method was shown to effectively reduce the residual Cl in the CeO2 microspheres. Overall, this work provides a clean manufacturing process for the preparation of SOFC electrode/electrolyte materials.

Novel Strategy for One-Step Production of Attenuated Ag-Containing AgCu/ZnO Antibacterial-Antifungal Nanocomposite Particles

Novel strategies have been developed to comply with Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) regulations to provide the same performances for antibacterial and antifungal materials. The strategy for producing composite materials by attenuating the silver (Ag) content and a one-step production technique without minimizing the antibacterial and antifungal performance was developed. In this study, attenuated spherical Ag containing spherical AgCu/ZnO nanocomposite particles have been synthesized from an aqueous solution of silver nitrate (AgNO3), copper nitrate (Cu(NO3)2 · 3H2O), and zinc nitrate (Zn(NO3)2 · 7H2O) by a facile one-step ultrasonic spray pyrolysis and hydrogen reduction (USP-HR) method. Characterization of AgCu/ZnO nanocomposite particles was carried out by various techniques such as X-ray diffraction analysis (XRD), scanning electron microscopy (FEG-SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The structural analysis showed that AgCu/ZnO nanocomposites were composed of face-centered cubic Ag, face-centered cubic Cu, and hexagonal ZnO phases. Antibacterial and antifungal properties of nanocomposite particles against Escherichia coli and Aspergillus niger were investigated by agar medium and broth medium methods. The obtained results indicate that produced nanocomposite particles possess antibacterial and antifungal properties (100%). The attenuated Ag in the AgCu/ZnO nanocomposite particles has the usage potential in different areas of the textile industry. In particular, the research on utilizing this nanocomposite in hand-made fiber production as an additive is of very high interest.

Sb-doped three-dimensional ZnFe2O4 macroporous spheres for N-butanol chemiresistive gas sensors

In this paper, the preparation process and gas sensing performance of Sb-doped three-dimensional spinel ferrite (3D ZnFe2O4) with well-assembled macroporous spherical structure have been investigated. Sb-doped 3D ZnFe2O4 macroporous spheres (MPs) were prepared through a one-step ultrasonic spray pyrolysis (USP) method by sacrificing self-assembly sulfonated polystyrene spheres (S-PSs). The interconnected macropores (an average pore size about 200 nm) can be observed in the as-prepared materials by SEM and TEM characterization, which provided the dual functions of accelerating the diffusion of gas molecules and providing more reactive sites. The XPS analysis showed that the element Sb existed as Sb5+ in doped samples. Compared with the pure 3D ZnFe2O4 MPs (response = 18), 0.5 % Sb-doped sample presented the response of 35.5–100 ppm n-butanol at 250 °C, and also revealed excellent selectivity and long-term stability to n-butanol. The greatly enhanced sensing performance of Sb-doped simples can be attributed to the construction of 3D spheres with interconnected macroporous structures and the modification of Sb doping. The formation of p-n junctions at interface through Sb doping also improved the sensing performance for n-butanol. In addition, the relative sensing mechanism of Sb-doped 3D ZnFe2O4 MPs for n-butanol sensing has been discussed in detail.

Superparamagnetic magnesium ferrite/silica core-shell nanospheres: A controllable SiO2 coating process for potential magnetic hyperthermia application

The control of coating shell becoming important to improve the applicability of magnetic nanoparticles. Herein, we present the scalable technique for preparing MgFe2O4/SiO2 core-shell nanospheres with finely tuned shell thickness and their efficiency in magnetic hyperthermia heating agent. At first, MgFe2O4 dense nanosphere derived from one-step ultrasonic spray pyrolysis (USP) technique. Silica shells were then coated on the as prepared nanospheres with tunable thickness from 10 to 30 nm. We show that the thickness of this coating is finely controlled at allowing our proposed level by using the required amount of SiO2 precursor (SiC8H20O4)/acidic catalyst (HCl) ratio where the surface area of core nanospheres are significantly considered. X-ray diffraction reveals the cubic spinel ferrite structure of core particles with crystallite size 9.6 ± 1.8 nm and Fourier transform infrared spectrum analysis confirmed the formation of SiO2. The morphological observation clarified the uniform and smooth SiO2 shell where core-shell nanostructure is highly monodispersed in a liquid medium. M-H loops confirmed the superparamagnetic nature of all samples at room temperature. Significantly reduced ion release concentration in an aqueous solvent of the coated nanospheres compared with uncoated sample demonstrates the hermetically coating feature of dense SiO2. This MgFe2O4/SiO2 core-shell nanospheres with thine SiO2 shell (10 nm) shows effective heating rate in the operative region (<46 °C) which makes them promising candidates for application as magnetic hyperthermia heating agent.

Synthesis and characterization of photocatalytically active crumpled-shape nanocomposites of nitrogen and sulfur co-doped ZnO–CeO2

In this study, crumpled-shape nanocomposite of nitrogen and sulfur co-doped ZnO–CeO2 (NSZC) was deposited on FTO substrate using one-step ultrasonic spray pyrolysis. Zinc acetate, cerium nitrate, and thiourea were dissolved in deionized water and used as starting solution. The samples were characterized using FESEM, XRD, UV–vis spectroscopy, EIS, and PL. The as-prepared nitrogen and sulfur co-doped ZnO–CeO2 nanocomposites were evaluated as high photocatalysts for degradation of methyl orange. Nearly 100% photocatalytic degradation of methyl orange was achieved for 180 min. The photoluminescence and electrochemical impedance spectroscopy revealed that co-doping of nitrogen and sulfur could promote the suppression of electron-hole recombination.

A One-Step Ultrasonic Spray Pyrolysis Approach to Large-Scale Synthesis of Silica Microspheres

This paper proposes a novel and simple one-step ultrasonic spray pyrolysis (USP) approach to prepare silica (SiO2) microspheres, in which only one chemical reagent—silica sol, is used as precursor. In this approach, aerosol droplets of silica sol generated by a ultrasonic nebulizer are transformed into its SiO2 microspheres through water evaporation, precipitation, drying, dehydration and densification in a tube furnance. The products were investigated by scanning electron microscopy, X-ray diffraction, energy dispersive spectrometer, Fourier transform infrared spectroscopy and thermogravimetry, respectively. Above characterizations showed that all the products were dry, unifrom, regular and smooth silica microspheres. The SiO2 concentrations of silica sols have a significant influence on the diameters and size distributions of the products. The microspheres prepared using silica sol with a low mass concentration (e.g. 10%) showed a narrow size distribution; most microspheres ranged from 1.0 to 1.4 μm in diameter. This approach shows great potential in large-scale synthesis of silica microspheres for two reasons: 1) USP is a continuous large-scale method; 2) silica sols are nontoxic and have been industrially produced.

Ultrasonic spray pyrolysis synthesis of three-dimensional ZnFe2O4-based macroporous spheres for excellent sensitive acetone gas sensor

The preparation process and gas sensitivity test of three-dimensional sphere spinel ferrites with well-assembled macroporous structures have been reported in this paper. The three-dimensional ZnFe2O4 macroporous spheres (3D ZnFe2O4 MPs) were prepared by one-step ultrasonic spray pyrolysis (USP), in which self-assembly sulfonated polystyrene (S-PS) spheres were employed as sacrificial template. The as-prepared samples possessed interconnected macroporous with pore diameters about 200 nm can be observed in TEM characterization, which provided more reactive active sites. The catalyst Pd was doped in 3D ZnFe2O4 MPs with the attempt of enhancing gas-sensing performance, which has been confirmed existed as Pd2+ formation by XRD and XPS analysis. In a comparison with pure 3D ZnFe2O4 MPs, the 0.5% PdO-dopded 3D ZnFe2O4 MPs exhibited a 2 times higher response (18.9) to 100 ppm acetone at 275 °C. Furthermore, the PdO- dopded 3D ZnFe2O4 MPs-based sensor also presented excellent selectivity and good long-term stability towards acetone. The outstanding sensing performance can be attributed to the 3D spheres with interconnect macroporous structure, electronic sensitization and catalytic effects of PdO. The relative sensing mechanism has been discussed in detail.

Deep insight into the photoluminescent monocrystalline particles: Heat-treatment, structure, mechanisms and mechanics

The red light emitting down-converting Ag@Y2O3:Eu3+ phosphor particles were synthesized by one-step ultrasonic spray pyrolysis and exposed further to the heat treatment at 1000°C (12h). A detailed investigation on structural and functional properties of the as-prepared and heat treated particles was conducted in a comparative manner. High-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRPD) and focus ion beam milling (FIB) revealed in a great consistency the poorly crystallized and porous nature of the as-prepared particles. Well-crystallized coarser primary nanocrystals of Y2O3:Eu3+and Ag, which are hierarchically organized in dense spherical Ag@Y2O3:Eu3+ phosphor particles, were obtained through the heat treatment. Along with the change of structural properties, down conversion (red luminescence at 612nm owing to the Eu3+5D0→7F2 electric dipole transition) and mechanical endurance were enhanced 4-fold and 5-fold via heat treatment, respectively. This comparative study implies a good correlation between mechanical and luminescence behavior of phosphors, both strongly influenced by the particles structural properties.

Mixed RuO2/TiO2 uniform microspheres synthesized by low-temperature ultrasonic spray pyrolysis and their advanced electrochemical performances

Uniformly-shaped, spherical RuO2/TiO2 particles were synthesized exclusively by one-step ultrasonic spray pyrolysis (USP) of a mixture of n-butylorthotitanate and ruthenium chloride acidic aqueous solutions. The USP temperature was 200 °C – quite below the typical conversion temperatures of the precursors to the oxides. Basic electrochemical properties of RuO2/TiO2 USP powders (as-prepared or additionally dried and/or thermally treated) in the form of a thin layer applied onto glassy carbon electrode are investigated and compared to the properties of powder synthesized at quite higher temperature of 800 °C. The coatings of activated titanium anode (ATA) were prepared from RuO2/TiO2 USP powders in order to check the anode electrolysis stability and to correlate the anode properties to those of native USP powders. Low-temperature material showed much better performances than high-temperature one. ATA obtained from low-temperature USP powder showed considerably higher stability. The obtained results are found to be in close correlation to the powder and coating structure, composition and morphology affected by subsequent thermal treatment of the material synthesized at low USP temperature.

Facile Spray Pyrolysis Synthesis of Various Metal-Doped MoO2 Microspheres for Catalytic Partial Oxidation of n-Dodecane

MoO2 microspheres doped with various metal species (Zr, Ti or Co) were simply prepared by means of a one-step ultrasonic spray pyrolysis. The dopant metal species were used as a reducing agent to promote the synthesis of MoO2, which is a metastable phase. The differences in electronegativity and radius between Mo and the dopant metal species influenced the structure and catalytic activity of the resulting MoO2 material. Partial oxidation of n-dodecane, a surrogate of Jet A fuel, was performed to evaluate the catalytic activity of MoO2 spheres doped with Zr, Ti, or Co. Among the produced samples, Co-doped MoO2 microspheres showed the highest H2 and CO yield as well as the highest C12 conversion. Various metal-doped MoO2 microspheres (with Ti, Zr, or Co dopants) were simply prepared by means of a one-step ultrasonic spray pyrolysis, where the dopant metal species were used as a reducing agent to promote the synthesis of MoO2. The differences in electronegativity and radius between Mo and the dopant metal species influenced the structure and catalytic activity for partial oxidation of n-dodecane.

N-doped ZnO-CuO nanocomposite prepared by one-step ultrasonic spray pyrolysis and its photocatalytic activity

Nanocomposite thin film of N-doped ZnO-CuO was deposited on glass substrate using ultrasonic spray pyrolysis method. Zinc acetate, copper acetate and ammonium acetate with different molar ratios were dissolved in water and used as precursors. A crumpled-shape morphology consisting of nanometer-sized particles was observed with FESEM. The elemental composition was evaluated with EDX analysis and the presence of nitrogen, oxygen, copper and zinc was confirmed. XRD analysis revealed the presence of ZnO and CuO crystalline phases with crystallite size of about 18 nm. The prepared nanocomposites exhibited high photocatalytic activity in degradation of methyl orange under UV light irradiation.

Self-Assembly Template Driven 3D Inverse Opal Microspheres Functionalized with Catalyst Nanoparticles Enabling a Highly Efficient Chemical Sensing Platform.

The design of semiconductor metal oxides (SMOs) with well-ordered porous structure has attracted tremendous attention owing to their larger specific surface area. Herein, three-dimensional inverse opal In2O3 microspheres (3D-IO In2O3 MSs) were fabricated through one-step ultrasonic spray pyrolysis (USP) which employed self-assembly sulfonated polystyrene (S-PS) spheres as a sacrificial template. The spherical pores observed in the 3D-IO In2O3 MSs had diameters of about 4 and 80 nm. Subsequently, the catalytic palladium oxide nanoparticles (PdO NPs) were loaded on 3D-IO In2O3 MSs via a simple impregnation method, and their gas sensing properties were investigated. In a comparison with pristine 3D-IO In2O3 MSs, the 3D-IO PdO@In2O3 MSs exhibited a 3.9 times higher response (Rair/Rgas = 50.9) to 100 ppm acetone at 250 °C and a good acetone selectivity. The detection limit for acetone could extend down to ppb level. Furthermore, the 3D-IO PdO@In2O3 MSs-based sensor also possess good long-term stability. The extraordinary sensing performance can be attributed to the novel 3D periodic porous structure, highly three-dimensional interconnection, larger specific surface area, size-tunable (meso- and macroscale) bimodal pores, and PdO NP catalysts.

Structure and Formation Model of Ag/TiO2 and Au/TiO2 Nanoparticles Synthesized through Ultrasonic Spray Pyrolysis

This article explains the mechanism of the metal/oxide core-shell Ag/TiO2 and Au/TiO2 nanoparticle formation via one-step ultrasonic spray pyrolysis (USP) by establishing a new model. The general knowledge on the standard “droplet-to-particle” (DTP) mechanism, nucleation, and growth processes of noble metals, as well as physical and chemical properties of core and shell materials and experimental knowledge, were utilized with the purpose of the construction of this new model. This hypothesis was assessed on silver (Ag)/titanium oxide (TiO2) and gold (Au) TiO2 binary complex nanoparticles’ experimental findings revealed by scanning electron microscopy (SEM), focused ion beam (FIB), high-resolution transmission electron microscopy (HRTEM), and simulation of crystal lattices. It was seen that two mechanisms run as proposed in the new model. However, there were some variations in size, morphology, and distribution of Ag and Au through the TiO2 core particle and these variations could be explained by the inherent physical and chemical property differences of Ag and Au.

One-step synthesis of Li-doped NiO as high-performance anode material for lithium ion batteries

The poor electronic conductivity and huge volume expansion of NiO are the vital barriers when used as anode for lithium ion batteries. In order to solve above issues, Li-doped NiO are prepared by a facile one-step ultrasonic spray pyrolysis method. The effects of Li doping on the morphology, structure and chemical composition of the Li-doped NiO powders are extensively studied. When used as lithium ion batteries anode, it is demonstrated that the doping of Li has significant positive effect on improving the electrochemical performance. After 100 cycles at 400mAg−1, The Li-doped NiO samples deliver a discharge capacity of 907mAhg−1, much more than that of un-doped sample (736mAhg−1). The improved electrochemical performances can be ascribed to the improved p-type conductivity and lower impedance, which are confirmed by Rietveld refinement, X-ray photoelectron spectroscopy and electron impedance spectroscopy.

Synthesis of nanoparticles-assembled Co3O4 microspheres as anodes for Li-ion batteries by spray pyrolysis of CoCl2 solution

Nanoparticles-assembled Co3O4 microspheres with different primary particle size are synthesized via a facile one-step ultrasonic spray pyrolysis process, using CoCl2·6H2O as precursor. The as-synthesized Co3O4 powders are directly used as anode material for Li-ion batteries without further calcinations. The primary particle size is tuned by controlling the spray pyrolysis temperature and its effects on the electrochemical performance of the prepared samples are systemically investigated. The results reveal that primary particles size exerts significant effect on the initial coulombic efficiency, specific capacity and rate performance. In addition, we find that the temperature of powder collector strongly influences the chlorine content in the products, which is resulted from the chloridization of Co3O4 by gaseous HCl from the off-gas. A simple and effective strategy is proposed to prevent the chloridization reaction. The sample with the smallest primary particle size and low Cl content shows the highest initial coulombic efficiency of 73% and a high reversible capacity of 1340mAhg−1 after 50 cycles at a current density of 200mAg−1.