Solution Combustion Synthesis Method Research Articles

Bimetal (CuNi and CuCo) substituted CeO2: An approach for low temperature dry reforming of methane

The solution combustion synthesis method was used to make CuNi substituted CeO2 (7.5 at.% of Cu+7.5 at.% of Ni), and CuCo substituted CeO2 (7.5 at.% of Cu+7.5 at.% of Co) catalysts. The catalysts were characterized by x-ray diffraction (XRD),XPS, BET surface area measurements, scanning electron microscopy (SEM), and H2-temperature-programmed reduction(H2-TPR). Further, these catalysts were tested for endothermic dry reforming of methane (DRM) reaction. The CuNi substituted CeO2 catalyst started dry reforming of methane (DRM) at around 350 °C, while the CuCo substituted CeO2 catalyst started DRM at around 450 °C. This indicates that the CuNi catalyst has a lower activation temperature for the DRM reaction compared to the CuCo catalyst. The CuNi substituted CeO2 catalyst converted CH4 better than the CuCo substituted CeO2 at all temperatures reaching 98 % conversion at 800 °C The CuNi substituted CeO2 showed higher H2/CO ratio in comparison to the CuCo substituted CeO2 but the long-term stability followed the opposite order. Thermal gravimetric analysis (TGA), SEM and O2-TPO were used to quantify as well as to understand the nature of carbon that had built up on spent catalysts and it is mostly amorphous. Transient studies have shown that along with the lattice oxygen participation, controlled methane decomposition step is necessary for stability of catalysts. Transient studies also recommended additional reaction steps during DRM where an exothermic methane partial oxidation step reduces the endothermicity of DRM. Also, CO2 activation also goes via the defect dissociation route, an additional step to the conventional carbon oxidation (CO2+C→CO) step. So, novelty of this work is in elucidating the exact role of lattice oxygen in imparting the activity and stability to the DRM catalyst.

Improving the Two-Color Temperature Sensing Using Machine Learning Approach: GdVO4:Sm3+ Prepared by Solution Combustion Synthesis (SCS)

The gadolinium vanadate doped with samarium (GdVO4:Sm3+) nanopowder was prepared by the solution combustion synthesis (SCS) method. After synthesis, in order to achieve full crystallinity, the material was annealed in air atmosphere at 900 °C. Phase identification in the post-annealed powder samples was performed by X-ray diffraction, and morphology was investigated by high-resolution scanning electron microscope (SEM) and transmission electron microscope (TEM). Photoluminescence characterization of emission spectrum and time resolved analysis was performed using tunable laser optical parametric oscillator excitation and streak camera. In addition to samarium emission bands, a weak broad luminescence emission band of host VO43− was also observed by the detection system. In our earlier work, we analyzed the possibility of using the host luminescence for two-color temperature sensing, improving the method by introducing the temporal dependence in line intensity ratio measurements. Here, we showed that further improvements are possible by using the machine learning approach. To facilitate the initial data assessment, we incorporated Principal Component Analysis (PCA), t-Distributed Stochastic Neighbor Embedding (t-SNE) and Uniform Manifold Approximation and Projection (UMAP) clustering of GdVO4:Sm3+ spectra at various temperatures. Good predictions of temperature were obtained using deep neural networks. Performance of the deep learning network was enhanced by data augmentation technique.

Improving the Two-Color Temperature Sensing Using Machine Learning Approach: GdVO4:Sm3+ Prepared by Solution Combustion Synthesis (SCS)

The gadolinium vanadate doped with samarium (GdVO4:Sm3+) nanopowder was prepared by the solution combustion synthesis (SCS) method. After synthesis, in order to achieve full crystallinity, the material was annealed in air atmosphere at 900 °C. Phase identification in the post-annealed powder samples was performed by X-ray diffraction, and morphology was investigated by high-resolution scanning electron microscope (SEM) and transmission electron microscope (TEM). Photoluminescence characterization of emission spectrum and time resolved analysis was performed using tunable laser optical parametric oscillator excitation and streak camera. In addition to samarium emission bands, a weak broad luminescence emission band of host VO43− was also observed by the detection system. In our earlier work, we analyzed the possibility of using the host luminescence for two-color temperature sensing, improving the method by introducing the temporal dependence in line intensity ratio measurements. Here, we showed that further improvements are possible by using the machine learning approach. To facilitate the initial data assessment, we incorporated Principal Component Analysis (PCA), t-Distributed Stochastic Neighbor Embedding (t-SNE) and Uniform Manifold Approximation and Projection (UMAP) clustering of GdVO4:Sm3+ spectra at various temperatures. Good predictions of temperature were obtained using deep neural networks. Performance of the deep learning network was enhanced by data augmentation technique.

Synthesis and Tuning of Electronic, Optical, and Photoelectrochemical Properties of Copper Metavanadate Alloys via Alkaline Earth Metal Substitution

Unlike the well-studied and technologically advanced Group III-V and Group II-VI compound semiconductor alloys, alloys of ternary metal oxide semiconductors have only recently begun to receive widespread attention. Here, we describe the effect of alkaline earth metal substitution on the optical, electronic, and photoelectrochemical (PEC) properties of copper metavanadate (CuV2O6). As a host, the Cu-V-O compound family presents a versatile framework to develop such composition-property correlations. Alloy compositions of A0.1Cu0.9V2O6 (A = Mg, Ca) photoanodes were synthesized via a time and energy-efficient solution combustion synthesis (SCS) method. The effect of introducing alkaline earth metals (Mg, Ca) on the crystal structure, microstructure, electronic, and optical properties of copper metavanadates was investigated by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), and Raman spectroscopy. The PXRD, TEM, and Raman spectroscopy data demonstrated the polycrystalline powder samples to be mutually soluble, solid solutions of copper and alkaline earth metal metavanadates and not simple mixtures of these compounds. The DRS data showed a systematic decrease in the optical bandgap with Cu incorporation. These trends were corroborated by electronic band structure calculations. Finally, the PEC properties exhibited a strong dependence on the alloy composition, pointing to possible applicability in solar water splitting, heterogeneous photocatalysis, phosphor lighting/displays, and photovoltaic devices.

Superior dielectric energy storage performance of ultrafine-grained BNT-SBT solid-solution ceramics by solution combustion synthesis

The micrometer scale grain size and large remnant polarization of Bi0.5Na0.5TiO3 (BNT) ferroelectric ceramics severely constrain the breakdown strength and energy efficiency, respectively, restricting their energy storage application despite their large polarization. Hereby, superior energy storage performance is reported by a synergistic strategy of introducing Sr0.7Bi0.2TiO3 (SBT) relaxor ferroelectrics and a solution combustion synthesis (SCS) method. The BNT-SBT solid-solution ceramics are comparatively investigated by the two methods, conventional sintering (CS) and SCS. An ultrafine average grain size of ∼ 0.39 μm was obtained in the SCS-derived ceramic, and thus exhibits an ultra-high critical electric field of 548 kV/cm, and a high recoverable energy density of ∼ 5.69 J/cm3. Those key energy storage parameters are superior to those of the previous reported samples prepared by the CS method. Meanwhile, a high energy efficiency ∼90%, a large power density of ∼ 130.44 MW/cm3 (at 320 kV/cm), and an ultrafast discharge time of ∼ 61.7 ns are also achieved. This study indicates that grain engineering combing with chemical design is an effective way to enhance the dielectric energy storage performance.

Tuning the composition of CuO/Cu2O composite powders via solution combustion method for supercapacitor application

In this work, the solution combustion synthesis method was implemented as a facile and in-situ procedure to adjust the composition of CuO/Cu2O composite by controlling the amounts of citric acid as fuel. Furthermore, the role of the Cu2O phase on the electrochemical properties was evaluated by preparation the single-phase CuO powders through calcination the CuO/Cu2O composite powders. The structural and microstructural results have shown that the synergic effects of Cu2O and CuO increased the electrochemical performance, including specific capacitance of 842 Fg−1 at 1 Ag−1 and high rate capability of 88 % by increasing the current density to 5 Ag−1. Furthermore, the CuO/Cu2O//activated carbon capacitor exhibited high electrochemical performance, such as an energy density of 27 Wh kg−1 at a power density of 1500 W kg−1 and outstanding cycling stability with 82 % capacitive retention for 2000 charge/discharge cycles, indicating a great potential for the practical application of CuO/Cu2O composite powders.

Pyridinic-N induced reversible adsorption of high-boiling-point organic gases on functionalized mesoporous carbon

Adsorptive capture of high-boiling-point organic gases (HBPOs) from hot flue gases is a key process in industry to tackle related environmental health or equipment clogging issues. However, few porous sorbents simultaneously achieve satisfactory adsorption capacity and regenerability due to strong affinity for HBPOs, compromising the economic viability and hindering the large-scale use of conventional disposable sorbents. In this work, we attempt to address this challenge by developing a functionalized mesoporous carbon (FMC) via the solution combustion synthesis method. Breakthrough experiments on phenanthrene and pyrene as representative HBPOs show that the FMC with lotus-shaped carbon sheet network, abundant 4–8 nm-concentrated mesoporosity, and oxygen/nitrogen-doped surface obtains unprecedented great capacity (1–2 orders of magnitude higher than reported values) and regenerability (peak desorption temperatures lower than respective boiling points). In situ characterizations and DFT simulations demonstrate the interfered π–π complexation as a highly reversible interaction between the carbonyl/pyridinic N-paired site and the polyaromatic adsorbate. The recyclability of FMC was demonstrated by negligible capacity reduction after 10 sorption cycles. This work showcases the potential for improving the economic feasibility of HBPOs capture by reducing the energy penalty and extending the sorbent lifetime.

Dry Reforming of Methane over Mn-modified Ni-based Catalysts

AbstractNi-based bi- and trimetallic Mn, Mg and aluminum containing catalysts prepared by the solution combustion synthesis (SCS) method were tested in dry reforming of methane (DRM). As a comparison 12 wt.% Ni/α-Al2O3 catalyst prepared by wet impregnation was also investigated. The catalysts were characterized by means of XRD, N2 physisorption, H2-TPR, CO2-TPD, NH3-TPD, TPO, CHNS, TGA, SEM and TEM. Formation of crystalline MnAl2O4 was observed at high temperatures during SCS. The average nickel particle size varied in the range of 12–36 nm. Addition of Mn promoted reduction of Ni and elevated the amount and strength of the basic sites. Graphical Abstract

Improving the electrochemical performance of LiNi0.5Mn1.5O4 by ZnO nanocrystals coating

The cathodic material LiNi0.5Mn1.5O4 was produced by the Solution Combustion Synthesis method (SCS). The as-made crystalline nanoparticles were annealed at 900 °C, obtaining micron-sized particles, and then coated with ZnO nanocrystals at a weight relation between 0.5 and 2.5 wt%, also using the SCS method. The nanocrystalline porous coating was confirmed by XRD, SEM and TEM. Electrochemical measurements verified that all materials coated with ZnO nanoparticles improved their electrochemical properties concerning the uncoated material, preventing degradation over the cycles, and stability along cyclic voltammetry cycles. It was observed that a 1 wt% ZnO coating presents the best improvement in discharge capacity and rate capability, and that the charge transfer resistance of the coated material is reduced to 1/3 of the uncoated one after 100 electrochemical cycles. In this work, the simple, time and energy saving SCS method was verified to obtain nanoshell-coated LNMO microparticles with improved electrochemical performance.

Synthesis of lithium doped magnesium ferrites and their vibrational and magnetic properties: Correlation of experimental and density functional theory

Recently, there has been an increased focus on investigating the possible use of ferrite nanoparticles as magnetic memory devices. In this study, we report on the structural, microstructural, Raman, density functional theory and magnetic characteristics of Mg1-xLixFe2O4 (x = 0, 0.15, 0.3, 0.45, 0.5 and 0.75). Samples were synthesized by solution combustion synthesis method. Samples were subjected to characterize X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Raman Spectra. XRD reveals that all synthesized samples show a single phase formation and unit cell volume, crystallite size varied with an increase in Lithium-ion concentration. SEM micrographs confirmed the porous nature increases with the rise of Li concentration. Particles are agglomeration and spherical type of nature was confirmed by TEM images. Further, Raman Spectra confirms the spinel cubic structure of MgFe2O4 nanoparticles belongs to the Fd3m space group. Despite the fact that the full unit cell has 56 atoms (Z = 8), the smallest Bravais cell consists of only 14 atoms (Z = 2). Consequently, in order to understand this effect, the electronic structure of pure and doped models was investigated through the Band Structure and Density of States (D.O.S.) profiles. First the crystalline structure of pure and Li-doped MgFe2O4 was analyzed based on the optimized lattice parameters and M − O (M = Mg, Li and Fe) bond distances. The band-gap was computed to be 2.54 eV being a direct transition between two points, in an excellent agreement with the experimental measurements. To investigate the temperature dependent magnetic properties, the M − H loops of Li doped MgFe2O4 nanoparticles traced at below and above room temperature over the applied magnetic field ±60 kOe. The M − H loops recorded at above and below room temperature demonstrated that the ferromagnetic nature of the sample. Further, the magnetic properties was investigated using temperature dependent FC and ZFC magnetization measurements. Above room temperature, the ZFC and FC curves show irreversibility and split at certain temperatures, as well as a broad maximum in ZFC curves at blocking temperature (TB). Saturation magnetization (Ms) values are higher at 15 K compared to 300 K, attributed to reduced thermal fluctuation. Our results suggest that synthesized materials are useful for room temperature magnetic memory device application.

Anti-oncogenic Potential and Inflammation Modulatory Response of Green Synthesized Biocompatible Silver Nanoparticles.

This study presents a novel approach to synthesizing silver nanoparticles (Ag NPs) using a solution combustion synthesis (SCS) method with Catharanthus roseus (C. roseus) leaf extract. The NPs were thoroughly characterized through X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), Transmission electron microscopy (TEM), and Selected area electron diffraction (SAED), elucidating their crystal structure. Notably, the synthesized Ag NPs exhibited a significant dose-dependent decline in viability of the MDA-MB 231 breast cancer cell line, with an IC50 value of 13.3 μg/mL, underscoring their potential as potent anticancer agent. Beyond cytotoxicity, the study pioneers an investigation into the biocompatibility of Ag NPs by blood hemolsysis, providing critical insights into their safety and biomedical applicability. Furthermore, this research uncovers a distinctive facet of Ag NPs, revealing their inhibitory effects on the inflammatory enzyme secretory phospholipase A2 (sPLA2), a recognized biomarker for breast cancer. The demonstrated in vitro and in vivo inhibition of sPLA2 highlights the multifaceted potential of Ag NPs in not only targeting cancer cells but also modulating inflammatory responses associated with breast cancer, positioning the study at the forefront of advancements in nanomedicine and cancer therapeutics.

Preparation and microwave absorption properties of CoFe2O4/NiCo2O4 composite powders

The magnetic spinel cobalt ferrite (CoFe2O4) powders had the high microwave absorption performance at the large thicknesses on account of the low permittivity. Combining the CoFe2O4 powders with other dielectric loss materials had been suggested to improve their impedance matching and microwave absorption performance. In this work, the microwave absorption performance of the CoFe2O4 powders was enhanced by adding the various amounts of the NiCo2O4 nanoparticles as dielectric loss material. The CoFe2O4-x NiCo2O4 composite powders (x = 0, 12.5, 25, and 50 wt %) were prepared by a facile two-pot solution combustion synthesis method. Although the X-ray diffraction peaks of NiCo2O4 phase were absent, but the decrease of saturation magnetization from 61 to 30 emu/g was related to the amount of NiCo2O4 material. Furthermore, the NiCo2O4 nanoparticles were nucleated and grown on the surface of spongy CoFe2O4 powders because the synthesized CoFe2O4 powders were added to the precursor solution of NiCo2O4 material containing the nickel and cobalt nitrates as oxidants and glycine as organic fuel. The microwave absorption performance was analyzed by measuring the permittivity and permeability spectra which were applied for evaluating the reflection loss versus frequency and thickness. The CoFe2O4-25 wt % NiCo2O4 composite powders had the higher microwave absorption performance including the high reflection loss of −40 dB and broad effective bandwidth of 5.6 GHz of Ku band (12–18 GHz) at a small matching thickness of 1.9 mm. The high microwave absorption performance of the x = 25 wt % sample was attributed to its better impedance matching via a proper combination of the permittivity and permeability values.

Thermoluminescence Studies of High Energy X‐Rays Irradiated Dy3+ Doped Mg0.65Zn0.3Al2O4:0.05Dy Nanophosphor

AbstractThe solution combustion synthesis method is employed to prepare Magnesium, Zinc, Aluminate doped with dysprosium (Dy3+) using the general formula Mg(1‐x‐y) Zn(y)Al2O4:xDy (x = 0.05 and y = 0.3 mol%). From X‐ray diffraction studies, the crystal structure belongs to a cubic close‐packed spinel structure with space group Fd3ˉm and an average crystallite size is 26.18 nm. In the Fourier transform infrared spectra, the peaks at 683.69 cm−1, 503.12 cm−1 correspond to the AlO6 groups. The peak temperature (Tm) from the Thermoluminescent glow curve is recorded at 235°C, 237°C, and 235°C, at irradiation doses of 600 Gy, 800 Gy, and 1000 Gy, respectively. The kinetic parameters are evaluated from the thermoluminescent glow curve by calculating the activation energy (E), order of kinetics (b), and frequency factor (s−1). Nanophosphor Mg0.65Zn0.3Al2O4:0.05Dy shows sub linear dose relationship at doses 600–675 Gy and 925–1000 Gy. Further, at doses between 675 and 925 Gy, it shows a super linear relationship. The optimum activation energy (E) of 0.77–0.82 eV and negligible fading make it suitable for high radiation thermoluminescent dosimetry.

Regeneration of LiNi0.6Co0.2Mn0.2O2 material from spent lithium-ion batteries by solution combustion synthesis method

LiNi0.6Co0.2Mn0.2O2 (NCM622) material was regenerated by solution combustion synthesis method using metal precursors obtained from the spent lithium-ion batteries. The structural, microstructural, and electrochemical properties of the regenerated cathode material were evaluated as a function of fuel type including citric acid, polyvinylpyrrolidone (PVP), cetyltrimethylammonium bromide (CTAB), and a mixture of CTAB and PVP fuels. The mixed CTAB-PVP fuel led to the layered crystal structure and porous microstructure with high specific surface area and pore volume. The regenerated cathode powders prepared by a mixture of CTAB and PVP fuels had a specific capacity of 156 mAh g−1 at 0.1C with a capacity retention of 94 % following 100 charge/discharge cycling at a current rate of 0.5C.

Combustion derived carbon with ultrahigh-mesoporosity and moderate surface affinity towards reversible low-volatile gas capture

Capturing naphthalene as a valuable chemical from waste gases via adsorption on porous sorbent materials is a promising approach to tackle such an environmental health issue with additional economic benefits. However, very few sorbents have simultaneously high adsorption capacity and good regenerability for the large-molecular and low-volatile naphthalene. Here we attempt to address this challenge by integrating key fabrication elements of a layer-by-layer network, rational mesoporosity, and highly reversible sites into a carbonaceous adsorbent (ECSC) using a facile and fast eruptive solution combustion synthesis method. Adsorption breakthrough and temperature-programmed desorption experiments show that the ECSC achieves all-round superior naphthalene capture performance with unprecedented high capacity, fast kinetics, and low desorption energy. The combination of in situ DRIFTS, XPS, and DFT calculations reveals the moderate adsorption affinity of mitigated π–π stacking bonding between tilted naphthalene molecule and surface pyridinic N. This work affords new insights for designing next-generation adsorbents for naphthalene removal and presents a way of overcoming the adsorption–desorption dilemma for gas purification.

Solution combustion synthesis of nanostructured Ni/W-containing electrocatalysts for hydrogen evolution reaction: The effect of fuel-to-oxidant ratio

The effect of varying fuel-to-oxidant ratio (φ) on the physicochemical properties and electrocatalytic performance for the hydrogen evolution reaction (HER) of nanostructured NiW materials produced via solution combustion synthesis (SCS) method was investigated. Agar and nickel nitrate served as the fuel and oxidant, respectively. TGA-MS results revealed that a fuel-to-oxidant ratio of 9 (φ9) provides the optimal conditions for reducing metal oxides to metallic phases due to the highest emission of reducing gas species (H2, CH4, and NH3). N2 adsorption/desorption measurements indicated that under fuel-rich conditions (φ > 1), both the specific surface area and porosity expanded with increasing the fuel quantity. Microscopy characterization was found to be consistent with N2 adsorption/desorption and TGA-MS results, revealing that the increased gas expulsion from higher fuel content led to more pronounced coral-like structures comprising of nano-sized particles and pores. Evaluation of electrocatalytic activity in an acidic medium (0.5 M H2SO4) revealed that the φ9 sample demonstrated the highest electrocatalytic HER performance. XRD and XPS analyses correlated well with this result, attributing the enhanced HER activity to the presence of the Ni0.9W0.1 metallic phase, limited oxide formation, and the highest proportions of metallic Ni and W atomic states, beyond mere surface area effects. Consequently, this study provides valuable insights into the importance of the fuel-to-oxidant ratio in optimizing the SCS method for controlled synthesis of nanostructured NiW materials in terms of morphology and composition, with implications for their potential development as high-performance, cost-effective electrocatalysts.

Photocatalytic degradation of azithromycin formulation in aqueous solution by doped titanium dioxide/fiberglass-rubberized silicone photocatalytic membrane

The objective of this work was to develop a novel photocatalytic membrane for the photocatalytic degradation of azithromycin formulation from aqueous solutions which, in addition to a high photocatalytic activity, should have a good mechanical and physico-chemical stability over time. Thus, the Nb-TiO2 and Nb-Fe-TiO2 photocatalysts were prepared by the solution combustion synthesis method, and then they were manually embedded in a fiberglass – rubberized silicone support. The mineralogical, morphological, and structural characterization of the obtained materials showed that both niobium and iron replace titanium in the titanium dioxide network, thus confirming the synthesis of new photocatalysts. The results of the photocatalytic oxidation tests showed a good photocatalytic activity of the developed photocatalytic membranes (degradation efficiency of up to 70% in the first 15 min of irradiation), this being on the one hand attributed to the increase of the specific surface of the photocatalyst by introducing niobium into the photocatalyst structure, and on the other hand due to the triggering of the Fenton photo oxidation mechanism due to the presence of trivalent iron in the photocatalyst structure. Also, the results indicated an excellent mechanical and physico-chemical resistance of the photocatalytic membranes, they are being practically inert to the harsh conditions in the photocatalytic reactor.

Structural and luminescence performance of the Eu3+ doped alkaline combined metal oxide-based sodium phosphate phosphors; NaMPO4 (M = Mg, Ba, and Ca) for LED applications

The present research module is about the synthesis of Eu3+ ions-doped NaMPO4(M = Mg, Ba, and Ca) phosphate phosphors by the solution combustion synthesis method. The phase formation and chemical structures of alkaline combined metal oxide-based sodium phosphate phosphors are characterised by X-ray powder diffraction (XRD) and FT-IR measurements. Optimized crystal geometries were generated by employing VESTA software. The crystallite size was calculated from the full width at half maximum (FWHM) of the diffraction peak using the Scherrer formula. G-Fourier transformation software (G-FT) was adopted for generating electron density mapping of NaMgPO4 phosphors, 2D mapping, and 3D chicken plots showing crystal sites occupied by the compound’s constituent elements. The particle size distribution was confirmed by XRD diffraction, and SEM analysis found approximately 12 μm. UV–visible and photoluminescence spectroscopy uncover the optical traits of the prepared phosphor. Photo-emissions of Eu3+doped alkaline combined metal oxide-based sodium phosphate phosphors were monitored at possible excitation wavelengths. The orange-red peak observed at 592 nm and 598 nm occurs due to 5D0-7F1 electric dipole transitions. The peak observed at 618 nm corresponds to the forbidden f-f transitions 5D0-7F2. It is worth mentioning that absorption bands originating from the corresponding 5D0-7F2 transition widen the band region; hence, the stark effect becomes complicated. A low-intensity peak of 688 nm was observed in the NaCaPO4 phosphors, attributed to the 5D0-7F3 transition. Chromaticity coordinates and energy level transitions may determine the colour emission materials. The CIE coordinates of NaMPO4:Eu3+phosphors exhibit reddish emission and find application in light-emitting diodes (LEDs) and illuminating displays.

Green-light emitting Tb(III) doped Gd2Si2O7 nanocrystals: Structural and optical measurements for NUV excitable cool LEDs

Cool-green light-emitting Gd2-xTbxSi2O7 (x = 1–6 mol%) doped phosphors were synthesized through the self-sustained solution combustion synthesis (SCS) method. The prepared nanomaterials were characterized via different structural and optical analysis. XRD measurements revealed that the doped samples were structured into a stable triclinic structure. The percentage difference in ionic radii (Dr) between Gd3+ and Tb3+ ions is 1.59%, which authorizes the replacement of Gd3+ ions via the Tb3+ ions. Williamson-Hall (W-H) method, retaining the Scherrer formula, is applied to calculate the average crystallite size of doped phosphors. A Kubelka-Munk function is used to deduce the energy band gap (Eg) values for pure Gd2Si2O7 and representative doped Gd1.96Tb0.04Si2O7 nanophosphors. The morphological studies revealed the random dispersion of agglomerated particles in the nano-range. The electric dipole (ED) 5D4→7F5 transition at 543 nm is accountable for relevant green-light emission. The obtained coordinates fall in the green region of the CIE (1931) triangle and replicate the potency of designated nanomaterials in the design and architecture of R-G-B phosphor-based LEDs.

Tin and lanthanum modified Ni/CeO2 catalyst systems for low temperature steam reforming of ethanol

This work examines the Ni–Sn/Ce–La–O catalyst systems for low-temperature stream reforming of ethanol. Catalysts of 5 and 20 wt% metal loading, and different Ce:La ratios are prepared by ultra-sonication assisted solution combustion synthesis method. Catalysts at total metal loading 5 wt% with 33 and 67 at. % La and optimum Sn (Ni:Sn = 14:1) demonstrate better efficiency compared to the Ni/CeO2 catalysts. At 20 wt% metal loading and Ni:Sn = 1:1 atomic ratio, catalytic activity degrades. The best activity and stability are revealed for the N14S1(5)/CL21 catalyst with 5 wt.% total metal loading, Ni:Sn = 14:1, and Ce:La = 2:1 mol ratio. Physico-chemical characterizations (XRD, H2 -TPR, NH3-TPD, Raman, FESEM, TEM, XPS, N2 adsorption-desorption, DTA/TGA, etc.) are performed to understand the role of the metal loading, Sn, and La in the catalytic activity and coke deposition behavior.