Simple Solution Combustion Synthesis Research Articles

Copper-manganese oxide catalysts prepared by solution combustion synthesis for total oxidation of VOCs

A set of Cu-Mn oxides was prepared through the simple and effective solution combustion synthesis method by varying the relative amount of copper and manganese. The physico-chemical properties of the samples were investigated through complementary techniques such as N2 physisorption at − 196 °C, XRD, HR-TEM, Raman spectroscopy, temperature programmed analyses (H2-TPR, O2-TPD, and NH3-TPD), and XPS. The prepared catalysts were tested for the total oxidation of volatile organic compounds (ethylene, propylene, and toluene). The best performances, in terms of total VOC oxidation, were achieved with a copper content ranging from 15 at% to 45 at%. The catalytic test outcomes demonstrate the beneficial effect of acidic sites, oxygen mobility, and redox ability. In particular, ethylene oxidation is mainly favored by oxygen vacancies and redox properties, while propylene and toluene oxidation is mostly enhanced by acidic sites. All the catalysts prepared can totally oxidize the examined pollutants examined below 310 °C. Moreover, the binary oxides exhibit good catalytic stability over a time-on-stream of 7 h and low water vapor inhibition (5 vol% H2O in the gas stream).

Samarium ion-doped calcium silicate: A promising material for fabrication of light emitting diodes

In this work, calcium silicate nanophosphors (CaSiO3) doped with Sm[Formula: see text] ions were prepared at [Formula: see text]C by a simple solution combustion synthesis technique. The particle size, functional groups and morphology of the prepared phosphors were identified by X-Ray diffraction (XRD), Fourier transform infrared (FTIR), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) techniques. The monoclinic phase of the nanophosphors was confirmed by X-ray diffraction studies. The effective excitation of the nanophosphors near the UV region and their yellow emission were confirmed by photoluminescence studies.

Facile synthesis of porous AlN@C supporting material for stabilizing phase change thermal storage material

Impregnating Phase Change Materials (PCMs) into a porous medium is a promising way to stabilize their shape and improve the thermal conductivity. In this work, we adopt a new process to prepare AlN@C porous medium as a supporting material to stabilize the paraffin PCMs. The AlN@C porous medium is prepared by a simple solution combustion synthesis method. It leads to a lower nitridation temperature-1500 °C (at least 200 °C lower than conventional method) and also the porous structure can be controlled by stoichiometric ratio of fuel to oxidizer. The enthalpy reaches 120.5 ± 0.7 to 139.7 ± 0.4 J/g. The thermal conductivity is increased to 145 ± 3% than pure paraffin. Meanwhile, the composite PCMs shows a good thermal reliability and shape stability. In conclusion, this work might provide a facile method for synthesizing high-efficient porous medium, which can shape-stabilize the PCMs with potential applications in thermal energy storage and thermal management.

Hollow macroporous CeO2/β-Bi2O3 heterostructure sphere via one-step spray solution combustion synthesis for efficient photocatalysis

The spherical CeO2/β-Bi2O3 heterostructure with the hollow macroporous structure was synthesized by a simple one-step spray solution combustion synthesis (SSCS). The microstructure, phase composition and optical characteristics of the synthesized samples were investigated by HRTEM, FESEM, BET, XPS, DRS and other characterization methods. The results demonstrate that the prepared samples had a particle diameter of about 1–5 µm and the grain size of around 5.4 nm. The photocatalytic activity of the spherical CeO2/β-Bi2O3 was investigated by visible light degradation of RhB (97.22% in 120 min). Additionally, the heterojunction had a broader visible light absorption in the 400–700 nm range, a substantial red-shift in the absorption edge, and a smaller band gap of 2.54 eV compared to pure CeO2 or β-Bi2O3 materials made using the traditional SCS approach. The spherical shape and large specific surface area (54.625 m2·g−1) of the synthesized heterojunction allow for better coupling of CeO2 with β-Bi2O3, which further reduces the luminescence intensity, enhances light collection and charge transfer, and exposes more surface defects to achieve improved photocatalytic performance. Calculations using density functional theory (DFT) demonstrate that the heterojunction can speed up interfacial charge transfer and reduce the recombination of photogenerated charges, causing the reactants to undergo deep oxidation.

Synthesis of titanium oxyfluoride with oxygen vacancy as novel catalysts for pyrolysis of fluorinated greenhouse gasses to hydrofluoroolefins

BackgroundHydrofluorocarbons (HFCs) are potent greenhouse gasses with high global warming potential and the emission of which is strictly regulated by Kigali amendment. MethodsIn this paper, titanium oxyfluoride (TiOF2) was firstly synthesized by simple solution combustion synthesis in the absence of highly corrosive HF, among which calcination played an important role on the phase of the products. When the precursor was calcinated at 450 °C, pure TiOF2 could be obtained. Significant findingsThe pyrolysis of HFCs results showed that the 1,1-difluoroethane (HFC-152a) conversion over TiOF2 is about 53%, superior than TiO2 (40%) due to the enhanced Lewis acidity. Even compared with traditional metal fluoride catalysts (AlF3 and MgF2), TiOF2 held higher stability within 35 h, contributing to the suitable Lewis acidic sites. The formation mechanism of the Lewis acidity was systematically investigated: on one hand, F species made the binding energy of Ti spesies shift to high regions to enhance the Lewis acid strength of Ti species; on the other hand, more oxygen vacancies were generated by the introduction of F, which could act as the Lewis acid sites as well. Hence, this study provides a promising and potential candidate for the catalytic pyrolysis of HFCs.

Solution combustion synthesized copper foams for enhancing the thermal transfer properties of phase change material

Regardless of the high latent heat of organic phase change materials (PCMs) for thermal energy storage, their intrinsically low thermal conductivity has constrained their wide application. In order to improve the thermal conductivity of paraffin PCM, porous copper foams as supporting frameworks are fabricated by a simple solution combustion synthesis (SCS), using copper nitrate as oxidizer and starch as fuel. The SCS is conducted under inert atmosphere and the efficient exothermic reaction occurs at around 100 °C. At an optimal oxidant-fuel condition of 4.43 g copper nitrate to 2 g starch, a good porous copper scaffold is prepared, which is further shaped and sintered to form robust copper foams. Paraffin is infiltrated into the copper foams to form PCM composites and the thermophysical properties are analyzed. Due to the continuous copper skeleton as heat transfer path, the thermal conductivity of the composite is improved to 3.29 W m−1 K−1 from 0.25 W m−1 K−1 of pure paraffin. The enhanced heat transfer properties of PCM composites as-supported by the facilely SCS-derived copper foams can reinforce the application in solar thermal harvesting and thermal management.

A simple solution combustion synthesis and scintillation studies of undoped and Eu-doped BaMgAl10O17 nanoparticles for radiation detection

This study describes a simple route to the synthesis of the Ba1-xMgAl10O17: Eux (x = 0, 0.02, 0.035, 0.055, and 0.07) nanoparticles based on the solution combustion synthesis method. The morphology, luminescence properties, and structural analysis of the synthesized compounds were performed by field emission scanning electron microscopy (FE-SEM), photoluminescence (PL) spectra, energy dispersive analysis of the X-ray (EDS), and X-ray diffraction (XRD) techniques. The photoluminescence study showed an intense blue band centered at~447 nm caused by Eu2+. It was observed in all the samples. The radiation response of the synthesized BAM nanoparticles (NPs), were measured using a241Am alpha source. The results indicated that the BaMgAl10O17: Eu2+ (BAM: Eu) NPs have a good absolute efficiency and can be used as a suitable candidate to fabricate efficient scintillators for radiation detection.

Solution Combustion Synthesis of Bi2Mo3O12 and Bi2Mo3O12/MoO3 Composites with Enhanced Photocatalytic Properties

In this study, we synthesized Bi2Mo3O12 and Bi2Mo3O12/MoO3 composites through a simple solution combustion synthesis (SCS) route. The structure, morphology, and photocatalytic property for the degradation of Congo Red (CR) were characterized by x-ray diffraction, scanning electron microscopy (SEM), x-ray photoelectron spectroscopy and ultraviolet–visible spectrophotometer absorption spectroscopy. The phases of the samples were characterized to be Bi2Mo3O1and Bi2Mo3O12/MoO3. The SEM results showed Bi2Mo3O12 particles were uniformly distributed on the MoO3 sheets. Bi2Mo3O12 and MoO3 in the Bi2Mo3O12/MoO3 composites were clearly demonstrated by the lattice spacing from high-resolution transmission electron microscopy results. The maximum degradation rate of Bi2Mo3O12/MoO3 composite was 83% at 60 min, showing excellent photocatalytic performance. A possible mechanism is proposed for the degradation of CR over Bi2Mo3O12/MoO3 composites, in which h+ and ·O2− are the main active species and play an important role in the degradation of pollutants.

Temperaturna zavisnost luminescentnih osobina Sr2CeO4:Eu3+ nanofosfora - pristup mašinskim učenjem

In this paper we analyze possibilities of application of Sr2CeO4:Eu3+ nanopowder for temperature sensing using machine learning. The material was prepared by simple solution combustion synthesis. Photoluminescence technique has been used to measure the optical emission temperature dependence of the prepared material. Principal Component Analysis, the basic machine learning algorithm, provided insight into temperature dependent spectral data from another point of view than usual approach.

Synthesis of Al2O3, MgO and MgAl2O4 by solution combustion method and investigation of performances in partial oxidation of methane

Al2O3, MgO and MgAl2O4 nanocrystalline and mesoporous materials were prepared by simple solution combustion synthesis using urea and metal nitrates and the effect of metal nitrate/urea ratio was investigated. The metal oxides that were found suitable for catalytic purposes were tested in catalytic partial oxidation of methane (CPOM). It was observed that the oxidizer/fuel ratio could affect the structure phase, crystallinity and morphology of the synthesized materials. γ-Al2O3 was obtained when the equivalence ratio was 2, and at lower ratios, the obtained phase was α-Al2O3. The cubic MgO phase was obtained at each ratio but the material yield was low below the equivalence ratio of 4. Highly crystalline MgAl2O4 was obtained at fuel-rich conditions only. 10% (wt.) Ni loaded MgAl2O4-2 and MgO-4 showed high activity (>90% CH4 conversion) and product selectivity (>98% H2 and CO selectivity) at 800°C under 157,500lkg−1h−1.

Ag/CeO2 nanostructured materials for enhanced photocatalytic and antibacterial applications

Abstract Well crystalline Ag/CeO2 nano-structured material being utilized for its photocatalytic and antibacterial activities was synthesized via simple solution combustion synthesis (SCS) approach using tartaric acid as a fuel. Interconnection of Ag with CeO2 was investigated to determine its morphological, structural, crystalline, surface and optical properties using common characterization tools. The synthesized Ag–CeO2 materials are of high purity and well-crystalline, having a porous nature with an average pore size of ∼5–7 nm. As-synthesized Ag–CeO2 materials were utilized as photocatalyst for catalytic Rhodamine B (RhB) dye degradation under UV irradiation, showing the almost full degradation of RhB dye molecules in 150 min. As-synthesized Ag/CeO2 nanostructured materials were also investigated for their antibacterial activity toward gram positive (S. aureus) and gram negative (P. aeruginosa) strains of bacteria. The minimum inhibitory concentration for inhibiting the growth of S. aureus (gram positive) and P. Aureginosa (gram negative) were found to be 3.125 μg/ml and 6.25 μg/ml in the presence of Ag/CeO2 materials. The results obtained for Ag/CeO2 materials clearly displayed the significantly improved catalytic and antibacterial properties in comparison with pure CeO2.

Rapid One-Pot Synthesis of Α- and Β-Cu2V2O7 and Their Use in Photoelectrochemical Water Splitting

Photoelectrochemical (PEC) water splitting is a promising strategy to make high density chemical fuels via utilization of solar energy using semiconductor materials. Oxide semiconductors, especially transition metal oxide semiconductors, offer various advantages such as stability, Earth-abundance and easy fabrication. A twin-photoelectrode tandem cell approach appears to be the most viable route to high solar-to-hydrogen conversion (STH) efficiency. In this configuration, the optimual energy bandgap for the semiconductor photoanode has been estimated to be ~ 2 eV. Ternary copper vanadates fulfill this criterion. The compound, Cu2V2O7 exists in two stable polymorphs at room temperature: orthorhombic α-Cu2V2O7 (Blossite) and monoclinic β-Cu2V2O7 (Ziesite). There are limited reports on the PEC behavior of β-Cu2V2O7, however, no corresponding reports on α-Cu2V2O7 are available. In this present work, we report the synthesis of these two polymorphs using a rapid and simple one-pot solution combustion synthesis and document their PEC behavior. The effect of various synthetic parameters were investigated and thus enabled to identify the optimum growth conditions to achieve phase-pure samples. Rietveld refinements along with powder X-ray diffraction confirmed the phase purity of the two polymorphs. The bandgap values of these oxides were estimated employing two different methods: Tauc plot from diffuse reflectance spectroscopy and surface photovoltage spectroscopy. These values agreed with those derived from density functional theory (DFT) calculations. Fermi level energies were quantified from contact potential difference (CPD) measurements which positioned them close to the conduction band minima (CBM) and thereby confirmed their n-type conductivity. The β-Cu2V2O7 phase showed higher photoactivity at lower applied bias; however, both phases showed similar photoactivity toward water splitting at higher applied bias.

Nanomolar Detection of Dopamine at ZnO/Graphene Modified Carbon Paste Electrode

In the present work, we demonstrate the electrocatalytic activity of few layer graphene and wurzite ZnO nanoparticles modified carbon paste electrode towards the oxidation of dopamine. Cost effective, simple and fast solution combustion synthesis was utilized for the synthesis of pure crystalline phase of wurzite ZnO nanoparticles. The commercial few layer graphene and ZnO modifiers were uniformly incorporated into the carbon paste matrix by simple bulk modification technique. The modified electrode enhanced the current sensitivity and resolved the DA peak from interfering molecules such as ascorbic acid and uric acid. The electrode has a detection limit of 60 nM having a wide linear dynamic range of 80 μM–80 nM. The fabricated sensor has excellent stability and reproducibility. The sensor was successfully utilized for the quantification of dopamine in blood serum.

YVO4:Eu3+ nanopowders: multi-mode temperature sensing technique

In this paper we study several temperature sensing techniques using the same thermographic phosphor: luminescence intensity ratio, lifetime, rise time. Moreover, we analyze some recently presented techniques, based on host luminescence intensity ratio method and delayed gate intensity ratio technique. We have selected YVO4:Eu3+ nano powder as an appropriate material for this study, because it has easily detectable luminescence rise time and host luminescence. The material was prepared using simple solution combustion synthesis. The time resolved analysis of emission spectra was achieved using the streak camera system. We present a very detailed analysis of measured lifetimes and rise times of all emission lines and their temperature dependence. We propose a multi-mode temperature sensing technique based on the concept of luminescence detection part of the temperature sensor capable of switching between several measurements modes to obtain the best sensitivity in desired range of operation.

Improved morphology and optimized luminescence of Eu3+-doped La2Ce2O7 composite nanopowders by surfactant-assisted solution combustion synthesis

In this paper, the red-emitting La2Ce2O7:Eu3+ composite nanopowders were successfully prepared via simple solution combustion synthesis (SCS) and surfactant (polyvinyl alcohol)-assisted solution combustion synthesis (PVACS), and characterized by X-ray diffraction, scanning electron microscopy, photoluminescence emission and excitation spectra, as well as fluorescent decay measurements. The X-ray diffraction results suggested the formation of La2Ce2O7 composite solid solution, and the introduction of Eu had little influence on the structure of the composite. The La2Ce2O7:Eu3+ composite showed controlled nanopowders (from 10 to 120 nm) with well-distributed morphologies under the assistance of certain amount of surfactant and subsequent heat-treatment process. The photoluminescence measurements indicated that the samples could be efficiently excited with blue light (467 nm), and exhibited the characteristic red emission of Eu3+ ion at 616 nm corresponding to the 5D0 →7F2 transition. The optimal concentration of activator Eu3+ ion was confirmed at about 15 mol% as the total amount of cations was considered. Moreover, the relative emission intensity, fluorescent lifetime and quantum efficiency of the La2Ce2O7:Eu3+ composite powders prepared by PVACS were compared with those achieved by simple SCS and traditional solid state reaction, which further confirmed the merits by PVACS. These results may facilitate the optimized composite nanopowders as a potential candidate for solid state lighting owing to the coincidence of 467 nm excitation light with the emission of InGaN chips in white light-emitting-diodes.

Template free synthesis route to monophasic BaMgAl10O17:Eu2+ with high luminescence efficiency

Luminescence properties of BaMgAl10O17:Eu2+ phosphors are greatly affected by its pure phase and uniform morphology. Hitherto different synthesis techniques have been adopted to achieve the same but phase purity and good crystallinity still remain desirable for BaMgAl10O17:Eu2+ nanophosphor. To obtain a highly intense blue light emitting BaMgAl10O17:Eu2+ nanophosphor, it was prepared in the absence of templates and additives by a simple solution combustion synthesis technique. The obtained powders were further acid leached and heat treated at 600 °C under argon atmosphere. BaMgAl10O17:Eu2+ samples obtained after this treatment show pure phasic characteristics having radical improvement in crystallinity with transformed morphology from multifaceted to rod-like. This structural modification has led to substantial increase in photoluminescence emission intensity of about 65% in comparison to the samples prepared by conventional solution combustion synthesis route.

Effects of temperature and pressure on luminescent properties of Sr2CeO4:Eu3+ nanophosphor

In this paper we describe the synthesis and characterization of the Sr2CeO4:Eu3+ nanopowder and possibilities of its application for temperature and high pressure sensing. The material was prepared using simple solution combustion synthesis. X-ray powder diffraction (XRD), scanning electron microscope (SEM) and photoluminescence (PL) techniques have been used to confirm and characterize the prepared material. Time resolved analysis of emission spectra was achieved by using the streak camera system. Measured lifetime values of luminescence emission and the intensity ratios of spectral lines were used for determining the calibration curves for remote temperature sensing. We have analyzed sensitivity improvement of the intensity ratio method by using a temporal evolution of emission lines and simulation of delayed gating of one of them. Pressure effects on optical properties of Sr2CeO4:Eu3+ nanophosphor are also investigated.

Solution combustion synthesis of heterostructure bismuth titanate nanocomposites: Structural phases and its correlation with photocatalytic activity

Bi2O3/TiO2 nanocomposites were prepared by simple and cost effective solution combustion synthesis route. The structural, textural, surface composition and optical properties of Bi2O3/TiO2 solid solutions are influenced by the type of fuel, viz., urea and glycine used in the combustion process and its concentration. The prepared materials were characterized by powder XRD, SEM, TEM, UV–vis, photoluminescence and N2 adsorption study. The obtained materials were evaluated for the photocatalytic degradation of methylene blue and water splitting reaction for H2 generation under visible light irradiation. The BT-5 sample shows high photocatalytic activity which may be due to the supressed recombination of photo-generated electron hole pairs and the appropriate lattice match by the formation of Bi4Ti3O12-β-Bi2O3 p-n heterojunction phases.

ZnO-ZnS Heterojunctions: A Potential Candidate for Optoelectronics Applications and Mineralization of Endocrine Disruptors in Direct Sunlight.

Simple solution combustion synthesis was adopted to synthesize ZnO–ZnS (ZSx) nanocomposites using zinc nitrate as an oxidant and a mixture of urea and thiourea as a fuel. A large thiourea/urea ratio leads to more ZnS in ZSx with heterojunctions between ZnS and ZnO and throughout the bulk; tunable ZnS crystallite size and textural properties are an added advantage. The amount of ZnS in ZSx can be varied by simply changing the thiourea content. Although ZnO and ZnS are wide band gap semiconductors, ZSx exhibits visible light absorption, at least up to 525 nm. This demonstrates an effective reduction of the optical band gap and substantial changes in its electronic structure. Raman spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and secondary-ion mass spectrometry results show features due to ZnO and ZnS and confirm the composite nature with heterojunctions. The above mentioned observations demonstrate the multifunctional nature of ZSx. Bare ZSx exhibits a promising sunlight-driven photocatalytic activity for complete mineralization of endocrine disruptors such as 2,4-dichlorophenol and endosulphan. ZSx also exhibits photocurrent generation at no applied bias. Dye-sensitized solar cell performance evaluation with ZSx shows up to 4% efficiency and 48% incident photon conversion efficiency. Heterojunctions observed between ZnO and ZnS nanocrystallites in high-resolution transmission electron microscopy suggest the reason for effective separation of electron–hole pairs and their utilization.

Concentration dependent luminescence spectral investigation of Sm3+ doped Y2SiO5 nanophosphor

Sm3+ doped Y2SiO5 was prepared by a simple solution combustion synthesis using (oxalyl dihydrazide) ODH as a fuel. The prepared material was well characterized by the PXRD, FTIR, UV–Vis and SEM. SEM data reveals highly aggregate mass with highly porous structure. Photoluminescence studies for the prepared material show four prominent peaks at 561, 571, 600 and 646nm, when excited at the wavelength 405nm. These transitions are attributed to the intra 4f orbital change over from 4G5/2 level to the 6HJ. In the present study, it was observed that the transition 4G5/2→6H7/2 is the most intense transition, which is a consequence of both electric and magnetic dipole transition. Thermoluminescence experiments on γ-irradiated samples in the dose range of 300–600Gy are studied. The (TL) glow curves intensity greatly depends on the size of the nanoparticles, surface area and duration of γ-exposure which was evident from the experimental data. TL intensity parameters such as activation energy, frequency factor and order of kinetics were evaluated using Chen's peak shape method to analyze the TL characteristics of the phosphor.