Solution Combustion Process Research Articles

Crystal structure, synthesis and photoluminescent properties of a reddish-orange light emitting SrGdAlO4: Sm3+ nanophosphor

A series of reddish orange light emitting SrGdAlO4: Sm3+ nanophosphor was prepared by urea aided solution combustion process. Structural features of the prepared nanophosphor were described by the powder X-ray diffraction (PXRD) together with Rietveld refinement technique. The results authenticate the existence of single phased tetragonal lattice with space group of I4/mmm (139). The highly intense peak observed in the photoluminescence emission spectra of the synthesized nanocrystalline phosphors was observed at 600 nm owing to 4G5/2 → 6H7/2 transition upon excitation by 407 nm light. The estimated energy band gap of SrGd0.97Sm0.03AlO4 nanophosphor was found to be 5.45 eV. The critical distance value evaluated for non-radiative energy transfer comes around 17.52 Å. The main reason responsible for the observed concentration quenching phenomenon in emission intensity of the prepared nanophosphor beyond 3 mol % doping of Sm3+ was found to be dipole-dipole (d-d) type electric multipolar interaction. The refractive index of the optimized nanophosphor (SrGd0.97Sm0.03AlO4) comes around 1.682. The chromaticity coordinates were found to lie in the reddish-orange region of CIE (Commission Internationale De I'Eclairage) diagram. The vivid description of the photoluminescent and structural aspects validate the potential applications of synthesized nanophosphor as optical nanomaterials in phosphor converted white light emitting diodes (pc-WLEDs).

Nano-sized plate-like alumina synthesis via solution combustion

Nano-sized plate-like alumina is an important inorganic material in catalytic, ceramic and electronic applications due to its unique two-dimensional structure and properties, while its facile synthesis is still under investigation. In this work, nano-sized alumina plate was synthesized by solution combustion method with glycine and polyvinyl alcohol as composite fuels for the first time. The calcination temperature during solution combustion process was optimized as confirmed by XRD, FT-IR, TG-DSC, Raman, 27Al MAS NMR, SEM, TEM, and N2 physisorbtion. Obtained alumina displayed special nano-sized plate morphology and porous structure. It was further adopted as support for cobalt acetate and used as catalyst for selective oxidation of cyclohexane. This work develops a facile approach to synthesize two-dimensional plate-like alumina for catalytic application.

Magnetic and microwave absorption properties of FeNi3/NiFe2O4 composites synthesized by solution combustion method

FeNi3/NiFe2O4 composites were prepared by solution combustion synthesis method. The solution combustion process was conducted in a closed system by use of conventional and microwave heating. Phase evolution, microstructure, magnetic and microwave absorption properties were studied by X-ray diffraction, electron microscopy, vibrating sample magnetometry and vector network analyzer techniques. The amount of FeNi3 phase was tuned by heating mode and amount of nickel precursor. The composites with higher amounts of FeNi3 phase and larger sintered particles (0.4–0.8 μm) were synthesized by microwave heating. The highest value of saturation magnetization (81 emu/g) was attained in the NiFe2O4-45 wt % FeNi3 composite. The FeNi3/NiFe2O4 composites had the high permeability due to the high saturation magnetization. The composites synthesized by conventional heating showed the maximum reflection loss of −15 dB in Ku band (12–18 GHz) with the band width of 3.8 GHz.

Novel mixed metal oxide (ZnO.La2O3.CeO2) synthesized via hydrothermal and solution combustion process – A comparative study and their photocatalytic properties

Designing of novel semiconductor materials or enhance the potential of existing materials for the removal of the environmental pollutants is growing area of scientific interest. In this paper, novel binary ZnO.La2O3 (ZL) and ternary mixed metal oxides ZnO.La2O3.CeO2 (ZLC) are synthesized using hydrothermal and solution combustion approach. The synthesized materials are characterized by the various techniques such as XRD, FESEM, UV-DRS and BET surface analyzer to uncover the structural, morphological and optical properties of the materials. The photocatalytic activity was evaluated by taking Rhodamine B dye as a model pollutant and 125 W mercury vapor lamp was used as light source. Despite the low crystallinity, hydrothermally synthesized samples possess better activity as compared to the solution combustion synthesized samples, which is attributed to their regular morphology and large surface area. The large surface area provide the more active sites and the regular morphology enhance the lifetime of the charge carriers by helping in migration of the photoinduced species. The hydrothermally synthesized sample showed 94.99% degradation of RhB on irradiation for about 160 min in basic medium. Experiments were performed using different scavengers to find the role of the active species in the degradation process.

60Co-traces sorption in the presence of Fe(III)-59Fe in aqueous solutions by banana husk ash obtained through solution combustion process at different temperatures

60Co-traces sorption in the presence of Fe(III)-59Fe in aqueous solutions by banana husk ash obtained through solution combustion process at different temperatures

Structural, Magnetic, and Catalytic Evaluation of Spinel Co, Ni, and Co-Ni Ferrite Nanoparticles Fabricated by Low-Temperature Solution Combustion Process.

Here, we present the low-temperature (∼600 °C) solution combustion method for the fabrication of CoFe2O4, NiFe2O4, and Co0.5Ni0.5Fe2O4 nanoparticles (NPs) of 12–64 nm range in pure cubic spinel structure, by adjusting the oxidant (nitrate ions)/reductant (glycine) ratio in the reaction mixture. Although nitrate ions/glycine (N/G) ratios of 3 and 6 were used for the synthesis, phase-pure NPs could be obtained only for the N/G ratio of 6. For the N/G ratio 3, certain amount of Ni2+ cations was reduced to metallic nickel. The NH3 gas generated during the thermal decomposition of the amino acid (glycine, H2NCH2COOH) induced the reduction reaction. X-ray diffraction (XRD), Raman spectroscopy, vibrating sample magnetometry, and X-ray photoelectron spectroscopy techniques were utilized to characterize the synthesized materials. XRD analyses of the samples indicate that the Co0.5Ni0.5Fe2O4 NPs have lattice parameter larger than that of NiFe2O4, but smaller than that of CoFe2O4 NPs. Although the saturation magnetization (Ms) of Co0.5Ni0.5Fe2O4 NPs lies in between the saturation magnetization values of CoFe2O4 and NiFe2O4 NPs, high coercivity (Hc, 875 Oe) of the NPs indicate their hard ferromagnetic behavior. Catalytic behavior of the fabricated spinel NPs revealed that the samples containing metallic Ni are active catalysts for the degradation of 4-nitrophenol in aqueous medium.

Mesoporous Silica by Solution-Combustion Synthesis Followed by Etching

Mesoporous silica was synthesized through the solution-combustion process followed by etching with aqueous solution of sodium dodecyl sulfate (SDS). Combustion products were characterized by XRD, FTIR, SEM, TEM, HRTEM, and BET analysis. After etching, the specific surface, mean pore size, and volume of porous space in silica increased up to 390 m2/g, 15 nm, and 1.6 cm3/g, respectively. The synthesized mesoporous silica exhibited good performance in the tests on elimination of methylene blue from aqueous solution.

Carbon sphere-assisted solution combustion synthesis of porous/hollow structured CeO2-MnOx catalysts

Solution combustion and hard template are traditional and classical approaches to synthesize porous and hollow structured metal oxides. However, their combination for the construction of porous/hollow structured bimetal oxides has seldom studied. In this work, a novel modified solution combustion method is proposed to synthesize bimetal oxides, e.g. CeO2-MnOx, in which carbon spheres as hard template are introduced into the solution combustion process. The experimental results reveal that the added carbon spheres not only act as hard template to create hollow spaces after removing them, but also burn off themselves in the solution combustion process, and thus affect the crystallinity and oxidation state of manganese oxide. Importantly, CeO2-MnOx catalyst harvested by using the carbon sphere-assisted solution combustion method exhibits the highest catalytic activity toward CO oxidation, compared with those prepared from traditional solution combustion and traditional hard template method. X-ray photoelectron spectroscopy (XPS) and hydrogen temperature-programmed reduction (H2-TPR) analysis demonstrate that there is a strong interaction between CeO2 and MnOx, which is mainly responsible for its high catalytic activity toward CO oxidation. This work is expected to help us modify the solution combustion and design highly efficient catalysts.

Low-cost, large-scale, one-pot synthesis of C/Ni3(NO3)2(OH)4 composites for high performance supercapacitor

In this study, we report a series of carbon/nickel-based composites. The composites are prepared through a facile one-pot solution combustion method by using nickel nitrate hydrate (Ni(NO3)2·6H2O) as an oxidizer and glucose (C6H12O6) as a fuel material. The phase, component and electrochemical capacitive behavior of the as-prepared samples are investigated. The component of the obtained composites could be simply controlled by changing the ratio of NO3−/C6H12O6. Novel C/Ni3(NO3)2(OH)4 composites are obtained at high molar ratio of NO3−/C6H12O6 (larger than 9) for the first time. The as-prepared C/Ni3(NO3)2(OH)4 composite shows battery-type behavior and exhibits a specific capacity of 630 C g−1 (1260 F g−1) at the current density of 1 A g−1, which is ca. 2–10 fold higher than those of C/NiO composite (414 C g−1, 828 F g−1) and C/NiO/Ni composite (65 C g−1, 129 F g−1). In addition, C/Ni3(NO3)2(OH)4 composite exhibits an excellent rate performance (448 C g−1, 996 F g−1 at 10 A g−1) and good cyclic stability. The results indicate that the C/Ni3(NO3)2(OH)4 composite is a potential electrode material for electrochemical supercapacitor. This work also suggests that the solution combustion process is promising for large-scale production of materials for supercapacitors.

A Facile Solution Combustion and Calcination Process for the Preparation of Magnetic NiFe₂O₄/SiO₂ Nanocomposites.

A facile solution combustion and calcination process for the preparation of magnetic NiFe2O4/SiO2 nanocomposites was introduced, the as-prepared NiFe2O4/SiO2 nanocomposites were characterized by XRD, VSM, BET, FTIR, SEM, and TEM techniques. The results showed that the single ferrite phase of NiFe2O4 could be formed at 400 °C; the calcination temperature, the content of silica in nanocomposites, and the volume of absolute alcohol were three key factors to the properties of the magnetic NiFe2O4/SiO2 nanocomposites: with the volume of absolute alcohol increasing from 10 mL to 100 mL, the average grain size of NiFe2O4/SiO2 nanocomposites calcined at 400 °C for 2 h with the heating rate of 3 °C/min decreased from about 16.6 nm to 8.4 nm, while the saturation magnetization decreased from about 6.1 Am2/kg to 1.5 Am2/kg; with the calcination temperature increasing from 400 °C to 800 °C, the average grain size of NiFe2O4/SiO2 nanocomposites calcined for 2 h with the heating rate of 3 °C/min and absolute alcohol of 30 mL increased from about 11.0 nm to 14.1 nm, and the saturation magnetization increased from about 3.4 Am2/kg to 24.0 Am2/kg; at the same time, with the content of silica in nanocomposites increasing from 0 to 10 wt.%, the average grain size of NiFe2O4/SiO2 nanocomposites calcined at 400 °C for 2 h with the heating rate of 3 °C/min decreased from about 18.4 nm to 11.0 nm, while the saturation magnetization decreased from about 18.2 Am2/kg to 3.4 Am2/kg.

Effects of Oxidizing/Reducing Agent Ratio on Phase Purity, Crystallinity, and Magnetic Behavior of Solution-Combustion-Grown BiFeO3 Submicroparticles.

Fabrication of phase-pure well-crystalline BiFeO3 submicroparticles in large scale is of great importance for the utilization of this rhombohedrally distorted perovskite material in applications such as memory storage and spintronic devices and visible photocatalyst for the degradation of organic pollutants. In fact, because of the narrow temperature range of phase stabilization, the fabrication of phase-pure BiFeO3 in large scale remained elusive. We present the synthesis of phase-pure BiFeO3 particles of submicrometric dimensions (246-330 nm average size) through the adjustment of oxidizing/reducing agent ratio in solution combustion process utilizing glycine as reducing agent and nitrate precursors as oxidizing agent. Utilizing X-ray diffraction and Raman spectroscopy, we demonstrate that the BiFeO3 submicroparticles synthesized at equivalence ratio (Φe) close to 0.5 do not contain undesired impurities such as Bi2Fe4O9 and Bi24Fe2O39. Moreover, the submicroparticles are highly crystalline, possessing high room temperature magnetic moment and stable antiferromagnetic behavior across a wide temperature range. The superparamagnetic behavior at low magnetic field manifested by impurities attached to the BiFeO3 submicroparticles might lead to their use as effective magnetically separable photocatalysts.

Adsorption Kinetics of Bovine Serum Albumin onto Ni0.5Zn0.5Fe₂O₄/SiO₂ Nanocomposites Prepared via the Solution Combustion Process.

Magnetic Ni0.5Zn0.5Fe2O4/SiO2 nanocomposites were prepared via the solution combustion process, their structure and magnetic properties were investigated by XRD, SEM, TEM and VSM. The asprepared magnetic Ni0.5Zn0.5Fe2O4/SiO2 nanocomposites were characterized with the average grain size of about 20 nm, the specific magnetization of 31.6 Am2/kg, and the specific surface area of 117.0 m2/g. The adsorption kinetics of bovine serum albumin (BSA) from aqueous solution onto the magnetic Ni0.5Zn0.5Fe2O4/SiO2 nanocomposites at room temperature was investigated. The kinetics data related to the adsorption of BSA from aqueous solutions were in good agreement with the pseudo-second-order kinetics model in the initial concentrations of 0.2-0.8 mg/mL.

Thermoluminescence study of beta irradiated Sr2CeO4:Eu3+ phosphor synthesized using solution-combustion process

Eu3+ doped strontium cerate (Sr2CeO4:Eu3+) phosphor was synthesized by solution - combustion technique using urea as a reducer at initiating temperature of 600 °C. The morphological, structural and thermoluminescence (TL) properties of Sr2CeO4:Eu3+ were investigated. X-ray diffraction patterns revealed the polycrystalline nature of Sr2CeO4:Eu3+ with single phase. The scanning electron microscopy photographs shows that the particle size distributions of all phosphor powders are rather broad with particle diameters in the range from ~ 50 nm to ~ 2 µm. The TL glow curve was found which composed of two well defined peaks at around 323 and 372 K. The electron-trapping properties in terms of TL glow curves are discussed in detail. The TL intensity was recorded for different beta doses and it is seen to increase with increasing doses. A linear behaviour of the TL intensity and peak temperature versus irradiation dose was found for dose up to 185 Gy. The effect of different heating rates was also studied and is seen to cause slight peak temperature shifts. Repeated measurements on the same sample seem not to have any effect on peak temperature positions and TL intensity indicating the sample was stable. Different kinetic parameters like activation energy (E), frequency factor (s) and geometrical factor (μg) were calculated for different TL glow curves. Trap depths were also calculated by different methods including initial rise, variable heating rate and peak shape methods.

Analysis of Al2O3 Nano Particles and Its Deposition on Steel by Cold Spray Process

The aluminium oxide material are widely used in ceramics, refractories and abrasives due to their hardness, chemical inertness, high melting point, non-volatility and resistance to oxidation and corrosion. For this study of investigation Al2O3 nano particles were synthesized by solution combustion process and size was found to be 30 nm from X-Ray Diffraction (XRD). A thin layer of Al2O3 nano particles on mild steel can be obtained by various means i.e., heat treatment and coating technique process by using Cold Spray process. Heat treated mild steel at 400˚C shows rough surface roughness and shows fine surface compared Base Metal. Surface roughness is higher after deposition of Al2O3 nano particles on mild steel at 400˚C compared with Base Metal. Surface roughness is low after deposition of Al2O3 nano particles on mild steel at 400˚ C when compared with Heat Treated sample at 400˚ C. The hardness of the base metal is low when compared with heat treated mild steel at 400˚C. When compared with base metal the coated sample at 400˚C shows high hardness because of maximum deposition of Al2O3 nano particles on mild steel. The hardness is high after coating nano particles on mild steel at 400˚C. Coated samples are characterized by XRD, SEM and Rockwell hardness.

Response Surface Optimization on Adsorption of Methyl Blue onto Magnetic (1 - x)NiFe₂O₄/xSiO₂ Nanocomposites.

Methyl blue (MB) was adsorbed from aqueous solution by magnetic (1 - x)NiFe2O4/xSiO2 (x = 0-0.2) nanocomposites prepared via the facile solution combustion process. The effects of pH of MB solutions, silica content in nanocomposites and the calcination temperature for nanocomposites on the adsorption capacity of MB onto nanocomposites were investigated. Response surface methodology (RSM) based on three-level three-factorial Box-behnken design (BBD) was employed to optimize the adsorption technology of MB onto magnetic (1 - x)NiFe2O4/xSiO2 (x = 0-0.2) nanocomposites, the optimum adsorption conditions (pH value of 7.3, the silica content in nanocomposites of 10.3 wt.%, and the calcination temperature of 423 °C) were determined by the results of statistical analysis, and the linear term of the pH value, the silica content and the calcination temperature, the quadratic term of the silica content and the calcination temperature, and the interaction of pH value and the silica content in nanocomposites were significant factors to affect the adsorption. The adsorption capacity could reach 37.40 mg/g with the initial MB concentration of 100 mg/g under the optimum adsorption conditions.

High-performance carbon-coated ZnMn2O4 nanocrystallite supercapacitors with tailored microstructures enabled by a novel solution combustion method

Although ZnMn2O4 is widely studied as Li-ion battery anodes, it remains a challenge to tailor suitable microstructures of the oxide for supercapacitor applications. Carbon-coated ZnMn2O4 (C@ZMO) nanocrystallites showing high-performance pseudocapacitor behaviours in neutral aqueous electrolyte are for the first time successfully synthesised via a novel solution combustion process using polyethylene glycol as a multifunctional microstructure-directing agent. Controlling the molecular weight and amount of the polymer in the combustion solution enables the formation of highly-crystalline C@ZMO having substantially higher, by more than 5 folds, specific surface areas with mesoporous structures and conformal carbon coating via the one-pot synthesis process. The resulting C@ZMO supercapacitor electrodes in Na2SO4(aq) electrolyte exhibit ideal capacitive behaviours with specific capacitances up to 150 F g−1 and cycle stability showing no capacitance fade after 10,000 cycles at 60% of full capacity and >99% Coulombic efficiency. This study not only illustrates a new powerful synthesis route capable of producing conductive mesoporous crystalline oxide-based nanomaterials for energy storage applications but also reveals a new class of high-performance pseudocapacitive materials for neutral aqueous electrolytes.

An In Situ Formed, Dual‐Phase Cathode with a Highly Active Catalyst Coating for Protonic Ceramic Fuel Cells

AbstractComposite cathodes of solid oxide fuel cells (SOFCs) are normally fabricated by mechanical mixing of electronic‐ and ionic‐conducting phases. Here, a dual‐phase SOFC cathode, composed of perovskite PrNi0.5Mn0.5O3 (PNM) and exsoluted fluorite PrOx particles, produced in situ through a glycine–nitrate solution combustion process, is reported. When applied as the cathode for a BaZr0.1Ce0.7Y0.1Yb0.1O3‐based protonic ceramic fuel cell, the hybrid cathode displays excellent electrocatalytic activity (area‐specific resistance of 0.052 Ω cm2 at 700 °C) and remarkable long‐term stability when operated at a cell voltage of 0.7 V for ≈500 h using H2 as fuel and ambient air as oxidant. The excellent performance is attributed to the proton‐conducting BaPrO3‐based coating and high‐concentration oxygen vacancies of a Ba‐doped PNM surface coating, produced by the reaction between the cathode and Ba from the electrolyte (via evaporation or diffusion), as confirmed by detailed X‐ray photoelectron spectroscopy, Raman spectroscopy, and density functional theory‐based calculations.

Removal of Co by carbonaceous material obtained through solution combustion of tamarind shell

ABSTRACTNew carbonaceous materials were obtained through solution combustion process of tamarind shell in the presence of urea and ammonium nitrate, and all of them were tested for Co removal. The effect of temperature (from 600 to 1000°C) and water volume on surface texture of carbonaceous material and its adsorptive capacity was evaluated. Scanning electron microscope, Fourier transform infrared spectroscopy, X-ray powder diffraction, and Brunauer–Emmett–Teller (BET) model were used to characterize the obtained carbonaceous material before applying for the removal of cobalt. The point of zero charge was also determined. The results indicate that BET-specific surface areas ranged from 6.40 to 216.72 m2g−1 for the carbonaceous materials obtained at 600, 700, 800, 900, and 1000°C. The one obtained at 900°C (CombTSF900) was found to be the most effective adsorbent for the removal of Co(II) ions from aqueous solutions, with a maximum sorption capacity (Qmax) of 43.56 mg/g. Carbonaceous material obtained through the solution combustion process improves morphological characteristics of adsorbent in a short time, and could be used as an alternative method for the removal of cobalt.

Enhanced cycling properties and better rate capabilities of Al-doped LiMn2O4 nanorods and nanospheres

The paper reports a facile synthesis of Al-doped LiMn2O4 nanorods and the oleic-acid-treated LiMn2O4 nanospheres without the use of MnO2 as templates in a single step solution combustion process. The as synthesized pristine LiMn2O4, LiMn1.6Al0.4O4 nanorods and LiMn1.6Al0.4O4 nanospheres are characterized for the structural and morphological characteristics by using x-ray diffraction spectroscopy (XRD), energy-dispersive x-ray spectroscopy (EDX) and field effect scanning electron microscopy (FESEM). The LiMn2O4 pristine sample and Al-doped LiMn2O4 nanorods and nanospheres have been explored as lithium ion battery cathodes. The results reveal the enhanced structural and electrochemical properties of the samples with the Al-doping. The oleic acid treated sample shows the best cycling properties and higher rate capabilities even at large discharge current rates of up to 2000 mA g−1.

Investigation of solution combustion-processed nickel oxide p-channel thin film transistors

In this work, p-channel thin film transistors (TFTs) with a nickel oxide (NiO) active layer have been synthesized by a solution combustion process. The effect of synthesis parameters was investigated. It was revealed that the metal–acetylacetone complexes and metal–ammine complexes coexist in the solution precursor. The combustion of metal–acetylacetone complexes is dominant in the redox reaction, while the combustion of metal–ammine complexes completes the reaction of residual organic matter. The proportion of both complexes in the solution precursor is key for NiO synthesis, which is tunable by the precursor aging time. The annealing temperature is another key parameter. X-ray photoelectron spectroscopy analysis indicates that organic residues exist in the film annealed at low temperature. In contrast, with the increase in annealing temperature, the Ni3+-related components decreased while the intensity of Ni2+ in the film increased. This results in a decrease in the hole concentration and the degradation of device performance. The p-channel NiO TFTs with a field-effect mobility of 0.015 cm2 V–1 s–1 have been achieved via systemically optimizing precursor aging time and post-annealing temperature. This study successfully demonstrates the potential of combustion solution-processed NiO TFTs with p-channel characteristics.