Low Temperature Solution Combustion Synthesis Research Articles

Promoting effect of oxygen vacancies in Co/CoAl2O4 catalyst steered with a straightforward method on hydrogenation of furfural to 2-methylfuran

The exploitation of base metal catalysts to upgrade biomass chemicals remains a daunting challenge and a sustainable strategy. Here, a series of Co-Al spinel catalysts are rapidly prepared by low-temperature solution combustion synthesis for hydrogenation of furfural (FF) to 2-methylfuran (2-MF), in which oxygen vacancies are easily manipulated by regulating the proportion of glycine in the ingredients. The screened Co/CoAl2O4 incorporating adequate oxygen vacancies yields 2-MF over 97 % at 150 ℃ for 5 h, rivalling the state-of-the-art catalysts to date. Characterizations and DFT calculations attribute the success to oxygen vacancies, which not only enhance the adsorption of FF by changing the adsorption geometry, but also facilitate the hydrogen spillover from Co to substrate by moving down the d-band center of CoAl2O4. This study provides a versatile methodology for the efficient and low-temperature preparation of spinel and the construction of defect engineering on catalysts, enlightening the design of phenomenal catalysts.

Solution combustion synthesis of metal tungstates for chromium reduction and dye degradation for environmental remediation

Metal tungstates CuWO4 and ZnWO4 nanoparticles were synthesized by simple, efficient, low temperature solution combustion synthesis using metal nitrate and ammonium tungstate. The prepared samples were characterized by different physicochemical characterization techniques i. e.XRD, FTIR, SEM, EDAX, UV–vis DRS, PL and XPS techniques. The petal and flower like morphology of these samples were obtained by using SEM analysis. Based on this novelty, we have studied the photodegradation of methylene blue and rhodamine B dyes in visible light. Results of photocatalytic dye degradation reaction reveal that both the tungstate’s can be employed as photocatalyst under visible light irradiation. ZnWO4 nanoparticles show comparatively higher activity than that of CuWO4, it may due to structural property as well as completely filled d10 orbital of Zn. Both CuWO4 as well as ZnWO4 were also applied to reduce toxic Cr(VI) into harmless Cr(III). This work implemented for the betterment of environmental remediation to the society.

Thermal Analysis of Metal-Organic Precursors for Functional Cu:ΝiOx Hole Transporting Layer in Inverted Perovskite Solar Cells: Role of Solution Combustion Chemistry in Cu:ΝiOx Thin Films Processing.

Low temperature solution combustion synthesis emerges as a facile method for the synthesis of functional metal oxides thin films for electronic applications. We study the solution combustion synthesis process of Cu:NiOx using different molar ratios (w/o, 0.1 and 1.5) of fuel acetylacetone (Acac) to oxidizer (Cu, Ni Nitrates) as a function of thermal annealing temperatures 150, 200, and 300 °C. The solution combustion synthesis process, in both thin films and bulk Cu:NiOx, is investigated. Thermal analysis studies using TGA and DTA reveal that the Cu:NiOx thin films show a more gradual mass loss while the bulk Cu:NiOx exhibits a distinct combustion process. The thin films can crystallize to Cu:NiOx at an annealing temperature of 300 °C, irrespective of the Acac/Oxidizer ratio, whereas lower annealing temperatures (150 and 200 °C) produce amorphous materials. A detail characterization study of solution combustion synthesized Cu:NiOx, including XPS, UV-Vis, AFM, and Contact angle measurements, is presented. Finally, 50 nm Cu:NiOx thin films are introduced as HTLs within the inverted perovskite solar cell device architecture. The Cu:NiOx HTL annealed at 150 and 200 °C provided PVSCs with limited functionality, whereas efficient triple-cation Cs0.04(MA0.17FA0.83)0.96 Pb(I0.83Br0.17)3-based PVSCs achieved for Cu:NiOx HTLs for annealing temperature of 300 °C.

The effect of various fuels on the yield, structural and optical properties zinc zirconate nanocomposite

Various types of fuels were used in a low-temperature solution combustion synthesis of zinc zirconate nanocomposite at a pH of 7. In the synthesis, the fuels used were citric acid, glycine, urea, hydrazine hydrate, and ammonium nitrate while zirconium butoxide and zinc nitrate were the precursor sources of Zr4+ and Zn2+ ions, respectively. The samples were calcined for 2 h at a temperature of 600 °C. The study of the structural properties showed varied morphologies ranging from highly agglomerated surfaces, crystalline aggregates as well as nanorods. There was a gradual growth of zinc zirconate perovskite within phases of zirconia and zinc oxide. It was observed that there were prominent photoluminescence emissions spread from violet-blue into the yellow-white regions with peaks varying from about 400 to 490 nm. The energy bandgap of the nanocomposites was between 2.93 and 3.22 eV depending on the fuel used in the preparation of the sample.

Influence of Nitridation on Structural and Photoluminescence Behaviour of CaZrO3:Eu3+ Nanophosphors

Ca1-xZrO3:xEu3+ (x = 0.05) phosphors have been prepared by using the low temperature solution combustion synthesis. The prepared nano phospors are well characterized by powder X-ray diffraction, scanning electron microscopy, Fourier infrared spectroscopy and transmission electron spectroscopy. PXRD results showed orthorhombic phase and SEM images showed porous agglomerated morphology. Influence of nitridation on structural and photoluminescence properties of the phosphor were investigated for wide range of nitridation time. The photoluminescence (PL) intensity was found to vary with nitridation with small shift in the photoluminescence emission peaks. The probable reasons for the variation of photoluminescence with nitridation are discussed.

Effect of Flux Boric Acid (H3BO3) on Yttrium Silicate Y2SiO5:Dy3+ (9 mol%) Nanophosphors Its Characterization and Luminescence Studies

Flux Boric acid (H3BO3) doped on Y2SiO5:Dy3+ phosphors were synthesized by auto ignition based low temperature Solution Combustion Synthesis (SCS) using Oxalic acid dihydrate (ODH) as fuel. Powder X-ray diffraction (PXRD) patterns confirm the nano sized particles corresponding to JCPDS card 36-1476. The crystallite size of the samples estimated from Scherer's formula and Williamson-Hall (W-H) plots was found to be in the range ˜21 nm and 26 nm respectively. Scanning electron Microscope (SEM) micrographs infer addition of flux gives the enhanced grain growth and it attains smooth surface improves the crystallinity and particle morphology of the sample. Fourier transform Infrared (FTIR) data reveals the presence of M–O bonds and Y–O bonds and also the bands at 642 cm–1, 655 cm–1, 668 cm–1, 697 cm–1, 719 cm–1 are ascribed due to the B–O–B linkage in the borate network. Addition of flux on Thermoluminescence (TL) glow curves from 0.5 KGy–4 KGy acts as a sensitizer and the peak appearing at 185 °C is quite stable and can be named as "dosimetric peak" to use in TL phosphor. The kinetic parameters estimated by Chen's peak shape method was found to be second order with activation energy 0.82.

Modified Low Temperature Solution Combustion Synthesis and Electrochemical Properties of Li1-xNaxNi0.5Mn1.5O4(x=0.05, 0.10) Materials as Cathode for Lithium-Ion Batteries

Modified Low Temperature Solution Combustion Synthesis and Electrochemical Properties of Li1-xNaxNi0.5Mn1.5O4(x=0.05, 0.10) Materials as Cathode for Lithium-Ion Batteries

Effect of Temperature on Li-rich Layered Cathode Material 0.5Li2MnO3·0.5LiNi0.5Mn0.5O2 Prepared by a Low Temperature Solution Combustion Synthesis

Effect of Temperature on Li-rich Layered Cathode Material 0.5Li2MnO3·0.5LiNi0.5Mn0.5O2 Prepared by a Low Temperature Solution Combustion Synthesis

Effect of Zr doping on LiNi0.5Mn1.5O4 with ordered or disordered structures

Zr-doped LiNi0.5Mn1.49Zr0.01O4 and pristine LiNi0.5Mn1.5O4 with ordered and disordered structures were prepared by a low-temperature solution combustion synthesis method. The phase compositions, structural ordering and micro-morphologies of the products were characterized by X-ray diffraction, energy-dispersive spectroscopy, inductive coupled plasma, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy measurements. The electrochemical performances of the products were investigated by charge/discharge testing, cyclic voltammetry, and electrochemical impedance spectroscopy. The results indicate that the effects of Zr doping on ordered or disordered LiNi0.5Mn1.5O4 are different. Ordered LiNi0.5Mn1.49Zr0.01O4 shows much better cycling stability and rate capability than that of ordered LiNi0.5Mn1.5O4. In contrast, the cycling stability of disordered LiNi0.5Mn1.5O4 changes little, and the rate capability decreases after Zr doping. After 200 cycles at 1 C, the capacity retentions of ordered LiNi0.5Mn1.49Zr0.01O4 and LiNi0.5Mn1.5O4 are 95.0% and 78.0%, respectively, while the capacity retentions of disordered LiNi0.5Mn1.49Zr0.01O4 and LiNi0.5Mn1.5O4 are 98.6% and 95.1%, respectively. In particular, the specific capacity of ordered LiNi0.5Mn1.49Zr0.01O4 is as high as 129.4 mA h/g and retains 94.5% after 100 cycles at 10 C, whereas the specific capacity of ordered LiNi0.5Mn1.5O4 is only 103.0 mA h/g and retains 84.0% at the same conditions. The excellent electrochemical performance of ordered LiNi0.5Mn1.49Zr0.01O4 could be attributed to its better crystallinity, higher lithium diffusion coefficient (DLi), and lower polarization.

Cu doped LiNi0.5Mn1.5−xCuxO4 (x = 0, 0.03, 0.05, 0.10, 0.15) with significant improved electrochemical performance prepared by a modified low temperature solution combustion synthesis method

A series of Cu-doped LiNi0.5Mn1.5−xCuxO4 (x = 0, 0.03, 0.05, 0.10, 0.15) spinel samples have been successfully prepared using a modified low temperature solution combustion synthesis method. X-ray diffraction(XRD) and infrared spectroscopy(FT-IR) analysis are used to characterize the phase structure. Scanning electron microscopy(SEM) is used to observe the microstructure of the products. The electrochemical performance are studied by galvanostatic charge-discharge testing, cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS). No obvious secondary phases were observed in XRD patterns of as-synthesized LiNi0.5Mn1.5−xCuxO4 powders. The samples have a combination structure of ordered and disordered space group and the order degree increases with the increase of Cu doping content obtained from FT-IR spectra. The electrochemical performances show that although the specific capacity decreases with the Cu-doping content, the cycle-life both at room temperature and 55°C and the C-rate performance are remarkably improved. The factors of stable structure, grain refinement, better crystallinity and lower charge transfer resistance lead to the excellent performance of Cu-doped samples.

Synthesis, characterizations, antibacterial and photoluminescence studies of solution combustion-derived α-Al2O3 nanoparticles

In this work, we report a novel, economical, low temperature solution combustion synthesis (SCS) method to prepare α-Al2O3 (Corundum) nanoparticles. Powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), BET surface area and ultraviolet visible spectroscopy (UV–vis) measurements were used to characterize the product. Antibacterial studies were examined against gram −ve Klebsiella aerogenes, Escherichia coli, Pseudomonas desmolyticum and gram +ve Staphylococcus aureus bacteria by agar well diffusion method. The α-Al2O3 nanoparticles showed substantial effect on all the four bacterial strains. Photoluminescence (PL) measurements under excitation at about 255 nm show that the alumina nanoparticles have emission peaks at 394 and 392 nm.

Facile synthesis of high performance LiNi0.5Mn1.4Mg0.1O4 and LiNi0.5Mn1.4Al0.1O4 by a low temperature solution combustion synthesis method

Facile synthesis of high performance LiNi0.5Mn1.4Mg0.1O4 and LiNi0.5Mn1.4Al0.1O4 by a low temperature solution combustion synthesis method

Synthesis of multicolor emitting Sr2−xSmxCeO4 nanophosphor with compositionally tuneable photo and thermoluminescence

Abstract Despite extensive efforts to design a white light generating phosphor, single component phosphors which exhibit multi-color emissions are very limited. In this work we report the synthesis of novel single component colortunable strontium cerate (Sr 2 − x Sm x CeO 4 ) phosphor using facile low temperature solution combustion synthesis. A single-composition, color tunable phosphor is produced by doping with different concentrations of Sm 3+ (0.0 to 0.11) into the Sr 2 CeO 4 matrix. Chromaticity of Sr 2 − x Sm x CeO 4 depends on the Sm 3+ concentration. This is because of energy transfer from Sr 2 CeO 4 to Sm 3+ determines the emission colors of the phosphors. At low concentration of Sm 3+ , Commission Internationale d’Eclairage (CIE) coordinates that are very close to white light emission (0.317, 0.303) are observed. However, at higher dopant concentration ( x = 0.11 of Sm 3+ ) the compound exhibits red emission (0.407, 0.343). Hence, a single host multi-color emitting phosphor is realized by doping and energy transfer. Thermoluminescence studies are carried out for Sr 2 CeO 4 :Sm 3+ phosphor using γ-irradiation in the dose range of 0.5 to 5 kGy. The kinetic parameters, namely activation energy ( E ), frequency factor ( s ) and order of kinetics ( b ) were estimated by Chen’s glow peak shape method and are discussed in detail for their possible usage in dosimetry.

Essence of superparamagnetism in cadmium ferrite induced by various organic fuels via novel solution combustion method

An attempt has been made to enumerate the myriads of successful applications of magnetic materials in nano-regime via low-temperature solution combustion synthesis of cadmium ferrite using different organic fuels such as urea, oxalyl dihydrazide (ODH), glycine and ethylene glycol giving rise to 1D nanorods and monodispersed spherical nanoparticles, thereby exploring their applicability in nanoelectronic devices such as high speed integrated circuits as well as in biomedical field as contrasting agents used in magnetic resonance imaging (MRI) with enhanced magnetization. Thus, with appropriate selection of organic fuel and precursors (metal nitrates), single phase, cubic structured cadmium ferrites have been synthesized as depicted from FTIR spectroscopy and XRD patterns with particle size lying in 12–27nm regime as rendered from TEM micrographs. Magnetic studies in the shadow of Mössbauer studies prelude to the emergence of superparamagnetism with non-saturation of M–H loop and negligibly small values of remanence as well as coercivity at room temperature, hence attributing to its single domain as well as soft magnetic character. Moreover, the room temperature dielectric measurements show dispersion behavior with increasing frequency corresponding to low dielectric losses, hence making them suitable for applications in high-frequency devices. Thus, solution combustion methodology was successfully used as a key step in the synthesis of CdFe2O4 with highly superparamagnetic and soft character, thereby leading to products with different morphologies in nano-regime.

Improvement in the electrochemical properties of LiNi0.5Mn1.5O4 lithium-ion battery cathodes prepared by a modified low temperature solution combustion synthesis

The LiNi0.5Mn1.5O4 (LNM) spinel lithium-ion battery cathodes were prepared by a modified low temperature solution combustion synthesis method at 600°C for 3h. Structural analyses reveal that the modified method is an effective process to eliminate an impurity phase. In comparison with the LNM prepared by a conventional method, the modified sample has higher purity, better crystallinity, smaller amount of Mn3+ ions and higher structural ordering. It exhibits remarkably superior initial discharge specific capacity of 117.0mAh/g, and delivers a reversible capacity of ~116.0, 116.6, 113.8, 108.9 and 85.9mAh/g at 0.2C, 0.5C, 1C, 2C and 5C, respectively. While the LNM prepared by the conventional method offers a lower reversible capacity of ~96.3, 95.4, 89.1, 77.0 and 40.6mAh/g at the same rate. After 50 cycles, about 95.5% of reversible capacity is retained for the LNM prepared by modified method vs. 90.7% for the LNM prepared by the conventional method. It suggests that the modified method is a simple and effective method to prepare LiNi0.5Mn1.5O4 with high performance at low temperature and in short time.

Structural and luminescent properties of Eu3+-doped GdSrAl3O7 nanophosphor

Eu3+-doped GdSrAl3O7 nanophosphor with promising luminescent properties has been synthesized by low-temperature solution combustion synthesis. The structural properties examined by X-ray diffractometer, scanning electron microscopy, and transmission electron microscopy showed that pure tetragonal GdSrAl3O7: Eu3+ red nanophosphor having narrow size distribution in 50–55 nm range could be readily obtained at low temperature 550 °C. The photoluminescent excitation and emission spectra, life time, and concentration effect were studied in detail. Under excitation at 266 nm, Eu3+-doped GdSrAl3O7 nanophosphor revealed weak green emission and strong red emission attributed to 5D1 → 7F1–2 and 5D0 → 7F0–3 transitions of Eu3+ ion, respectively in the region of 525–700 nm. The red emission from 5D0 → 7F2 transition at 616 nm exhibits the highest intensity under the optimized concentration of 10 mol% after which the quenching mechanism became relevant. Quenching behavior of the europium in the GdSrAl3O7 host was explained by nonradiative cross-relaxation phenomenon. Moreover, Eu3+-doped GdSrAl3O7 nanophosphor can generate light from orange to deeper red by properly tuning the concentration of europium ions based on the energy transfer principle.

Synthesis and photoluminescence properties of a novel Sr2CeO4:Dy3+nanophosphor with enhanced brightness by Li+co-doping

A series of Dy3+(0.005–0.09 mol%) and Li+(0.005–0.03 mol%) co-doped strontium cerate (Sr2CeO4) nanopowders are synthesized by low temperature solution combustion synthesis.

Low-temperature solution combustion synthesis of high performance LiNi0.5Mn1.5O4

High-voltage LiNi0.5Mn1.5O4 spinels were synthesized by a low temperature solution combustion method at 400°C, 600°C and 800°C for 3h. The phase composition, structural disordering, micro-morphologies and electrochemical properties of the products were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and constant current charge–discharge test. XRD analysis indicated that single phase LiNi0.5Mn1.5O4 powders with disordered Fd-3m structures were obtained by the method at 400°C, 600°C and 800°C. The crystallinity increased with increasing preparation temperatures. XRD and FTIR data indicated that the degree of structural disordering in the product prepared at 800°C was the largest and in the product prepared at 600°C was the least. SEM investigation demonstrated that the particle size and the crystal perfection of the products were increased with increasing temperatures. The particles of the product prepared at 600°C with ~200nm in size are well developed and homogeneously distributed. Charge/discharge curves and cycling performance tests at different current density indicated that the product prepared at 600°C had the largest specific capacity and the best cycling performance, due to its high purity, high crystallinity, small particle size as well as moderate amount of Mn3+ ions.

Photoluminescence properties of gadolinium oxide nanophosphor

In this paper, we report low temperature solution combustion synthesis and characterization of rare earth oxide (Gd2O3) nanocrystalline phosphor. During the synthesis, glycine was used as a fuel. The final product was examined by well characterized techniques such as powder X-ray diffraction pattern (PXRD), UV-Visible absorption spectroscopy, photoluminescence (PL) measurements etc. The average crystallite size of the Gd2O3 nanophosphor was estimated using Scherrer's formula and found to be 36 nm. The UV-Visible absorption peaks observed at ~243 and ~305 nm. Further the band gap of 900 °C for 3 h calcined Gd2O3 nanophosphor were estimated by Wood and Tauc relation and it was found to be ~5.4 eV. A broad PL emission band at ~380 nm was observed at 230 nm excitation. According to Wang's proposal, this emission band may be attributed to recombination of a delocalized electron close to the conduction band with a single charged state of surface oxygen vacancy.

Structural, optical and EPR studies on ZnO:Cu nanopowders prepared via low temperature solution combustion synthesis

Cu (0.1 mol%) doped ZnO nanopowders have been successfully synthesized by a wet chemical method at a relatively low temperature (300 °C). Powder X-ray diffraction (PXRD) analysis, scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) spectroscopy, UV–Visible spectroscopy, Photoluminescence (PL) and Electron Paramagnetic Resonance (EPR) measurements were used for characterization. PXRD results confirm that the nanopowders exhibit hexagonal wurtzite structure of ZnO without any secondary phase. The particle size of as-formed product has been calculated by Williamson–Hall (W–H) plots and Scherrer's formula is found to be in the range of ∼40 nm. TEM image confirms the nano size crystalline nature of Cu doped ZnO. SEM micrographs of undoped and Cu doped ZnO show highly porous with large voids. UV–Vis spectrum showed a red shift in the absorption edge in Cu doped ZnO. PL spectra show prominent peaks corresponding to near band edge UV emission and defect related green emission in the visible region at room temperature and their possible mechanisms have been discussed. The EPR spectrum exhibits a broad resonance signal at g ∼ 2.049, and two narrow resonances one at g ∼ 1.990 and other at g ∼ 1.950. The broad resonance signal at g ∼ 2.049 is a characteristic of Cu 2+ ion whereas the signal at g ∼ 1.990 and g ∼ 1.950 can be attributed to ionized oxygen vacancies and shallow donors respectively. The spin concentration ( N) and paramagnetic susceptibility ( χ) have been evaluated and discussed.