Simple Solution Combustion Route Research Articles

Desired highly efficient Eu3+ activated GdCaAl3O7 orange-red emanating nanophosphors for UV excitable forensic and advanced information encryption and decryption applications

In the present work, orange-red emitting Eu3+ (1–8 mol %) doped GdCaAl3O7 nanophosphors are prepared by a simple solution combustion route. X-ray diffraction studies reveal that the prepared phosphors are in the tetragonal phase without any additional impurity peaks. Morphological studies clearly show the irregularly shaped network-type structures of the phosphors. Under UV light excitation (∼393 nm), photoluminescence (PL) emission peaks are recorded at ∼578, 590, 617, 651, and 701 nm, which correspond to the 5D0→7F0, 1, 2, 3, 4 transitions of Eu3+ ions, respectively. The photometric properties of the prepared nanophosphors reveal color tuning from the orange-red region to the pure red region with a color purity of ∼88.14 %. The optimized GdCaAl3O7:Eu3+ (3 mol %) nanophosphor is evaluated from an application perspective by developing latent fingerprints and lip prints. The visualized latent fingerprints under ∼254 and 375 nm excitations undoubtedly reveal levels I–III ridge features on various surfaces. The developed lip prints can discriminate the Suzuki's and Tsuchihashi’s categories. The information encryption and decryption capabilities of the nanophosphor on various surfaces were investigated by following screen printing technology, dip-pen and brush mode. The printed patterns revealed sharp, high resolution, uniform ink distribution under ∼254 nm UV excitation and invisible upon normal light. The overall results revealed that prepared GdCaAl3O7:Eu3+ (1–8 mol %) NPs exhibit excellent structural stability and intensive PL emission endorsing its applicability wide scope of areas.

Investigation of structural, electrical and magnetic properties of MnAlxFe2-xO4 ferrite nanoparticles processed by solution combustion route

Al doped Mn ferrite, MnAlxFe2-xO4 (x = 0.1, 0.2, & 0.3), nanoparticles were synthsized by facile and simple solution combustion route. Effect of Al3+ ions substitution on the structural, optical, electrical and magnetic properties were explored. X-Ray diffraction (XRD) results confirm the formation of pure cubic phase for all the synthesized nanoparticles having spinel structure. Various structural parameters like crystallite size, lattice parameter, site radii and bond lengths were estimated from XRD data. For the strain analysis and consideration of contribution of every peak in XRD data, W-H and N-R plots were analysed. Scannining electron microscopy (SEM) revealed the compact surface morphology with grain size in nano meter range. FTIR spectra confirmed the presence of metal stretching vibrations at tetrahedral and octahedral sites for all MnAlxFe2-xO4 nanoparticle compositions, which is typical of spinel ferrites with FCC structure. Raman spectroscopy helped in analysing metal stretching vibrations of the synthesized samples and obtained raman modes were found to be as predicted by group theory. Dielectric constant decreases with increase in frequency reflecting the normal behaviour of the ferrites. Dielectric loss also followed the same trend. Both the behaviours have been explained in view of Koop׳s theory and Maxwell–Wagner polarization-model. The synthesized ferrite samples exhibited the soft magnetic nature as confirmed by vibrating sample magnetometer. The room temperature hysteresis curves indicate the decrease in saturation magnetization as well as retentivity with the increase in Al3+ ions doping. The decrease in magnetic moment values have been explained on the basis of cation preference for the sites and also on weakening of exchange interaction upon aluminium doping.

One material, many possibilities via enrichment of luminescence in La2Zr2O7:Tb3+ nanophosphors for forensic stimuli aided applications

Engineering a single material with multidirectional applications is crucial for improving productivity, low cost, flexibility, least power consumption, etc. To achieve these requirements, novel design structures and high-performance materials are in urgent need. Lanthanide-doped nanophosphors have the greatest strengths and ability in order to tune their applications in various dimensions. However, applications of nanophosphor in latent fingerprints visualization, anti-counterfeiting, and luminescent gels/films are still in their infancy. This study demonstrated a simple strategy to enhance the luminescence of Tb3+ (1–11 mol %) doped La2Zr2O7 nanophosphors by conjugating various fluxes via a simple solution combustion route. The photoluminescence emission spectra reveal intense peaks at ~ 491, 546, 587, and 622 nm, which arises from 5D4 → 7FJ (J = 6, 5, 4, 3) transitions of Tb3+ ions, respectively. The highest emission intensity was achieved in the NH4Cl flux assisted nanophosphor as compared to NaBr and NH4F assisted samples. The colorimetric images of fingerprints visualized using the optimized nanophosphor on forensic related surfaces exhibit level –III ridge details, including sweat pores, the width of the ridges, bifurcation angle, and the successive distance between sweat pores, etc. These results are decisive parameters that clearly support the statement “no two persons have ever been found to have the same fingerprints”. The anti-counterfeiting security ink was formulated using optimized nanophosphor and various patterns were designed by simple screen printing and dip pen technologies. The encoded information was decrypted only under ultraviolet 254 nm light. All the designed patterns are exhibit not just what it looks/feel like and how better it works. As a synergetic contribution of enhanced luminescence of the prepared nanophosphor, the green-emissive films were fabricated, which display excellent flexibility, uniformity, and transparency in the normal and ultraviolet 254 nm light illumination. The aforementioned results revealed that the prepared NH4Cl flux-assisted La2Zr2O7: Tb3+(7 mol %) NPs are considered to be the best candidate for multi-dimensional applications.

Synergy of porous structure and cation doping in Ta3N5 photoanode towards improved photoelectrochemical water oxidation

Herein, a cross-linked porous Ta 3 N 5 film was prepared via a simple solution combustion route followed by a high-temperature nitridation process for photoelectrochemical (PEC) water oxidation. Meanwhile, the metal cations (Mg 2+ and Zr 4+ ) were incorporated into the porous Ta 3 N 5 to enhance the PEC performance. The porous Mg/Zr co-doped Ta 3 N 5 photoanode yielded a photocurrent density of 1.40 mA cm −2 at 1.23 V vs RHE, which is 5.6 times higher than that of the dense Ta 3 N 5 photoanode. The enhanced performance should be ascribed to the synergistic effect of porous structure and cation doping, which can enlarge the electrochemical active surface area and accelerate the charge transfer by introducing O N substitution defects. Subsequently, Co(OH) 2 cocatalyst was loaded on the Mg/Zr-Ta 3 N 5 photoanode to negatively shift the onset potential to 0.45 V vs RHE and further improve the photocurrent density to 3.5 mA cm −2 at 1.23 V vs. RHE, with a maximum half-cell solar to hydrogen efficiency of 0.45%. The present study provides a new strategy to design efficient Ta 3 N 5 photoelectrodes via the simultaneous control of the morphology and composition. A cross-linked porous Ta 3 N 5 film co-doped with Mg 2+ and Zr 4+ cations showed a significantly improved photoelectrochemical performance for water oxidation due to enlarged electrochemical active surface area, enhanced charge transfer ability, and accelerated surface reaction.

Surface adaptation prompted enhanced photo and thermoluminescence properties of Dy3+ doped wollastonite nanophosphor

The novel CaSiO3:Dy3+ (1–11 mol %) nanophosphors synthesized via simple solution combustion route and covered with silica (SiO2) by the Stöber method are reported in the present work. The X ray diffraction analysis verifies the phase purity of the synthesized samples. The diffraction peaks observed in the recorded powder x-ray diffraction patterns are in good relation with those known for the CaSiO3 structure. The photoluminescence and thermoluminescence properties of SiO2@CaSiO3:Dy3+ (3 mol %) nanophosphors were extensively investigated. The 3-fold enhancement in the photoluminescence intensity of nanophosphors after surface coating was observed, that may be due to light diffraction and multiplied by shell SiO2. The utility of the prepared samples in white light emitting diodes was confirmed by studying photometric properties. The thermoluminescence study of the samples with different γ-ray doses showed good linearity up to 4 kGy and, thereafter, the sub-linear behavior was noticed. The variation in the thermoluminescence intensity arises as a consequence of competition between different trapping centers. The aforementioned results signify that the present material was highly useful for display and dosimetry applications.

Evolution of shapes and identification of level II and III features of fingerprints using CaZrO3:Sm3+ fluorescent markers prepared via solution combustion route

Simple solution combustion route is used for the fabrication of CaZrO3: Sm3+ (1–11 mol %) nanophosphors using Aloe Vera gel as a fuel. The powder X-ray diffraction profiles confirm the pure orthorhombic phase. The granular type particles with non-uniformity in the size is observed. Photoluminescence emission spectra exhibit intense peaks at ∼571, 603, 651 and 708 nm, which are attributed to 4G5/2 → 6H5/2, 4G5/2 → 6H7/2, 4G5/2 → 6H9/2 and 4G5/2 → 6H11/2 transitions of Sm3+ ions, respectively. The photometric properties evident that the prepared samples emit bright orange - red light with 79% color purity. The average correlated color temperature value is found to be ∼3100 K. Thermoluminescence glow curves exhibit a broad, intense peak at ∼148 °C. The highest thermoluminescence intensity is recorded for 5 mol % of Sm3+ doped sample. The thermoluminescence intensity at ∼148 °C is found to increase with increase of γ-dose. The optimized CaZrO3:Sm3+ (5 mol %) nanophosphors used as a luminescent labeling agent for visualization latent fingerprints on various porous and non-porous surfaces under ultraviolet 254 nm and normal light. The obtained results exhibits well defined ridge details with high sensitivity, selectivity, and low background hindrance which showed greater advantages. Extensive fingerprint details, namely level II and III features are clearly revealed. Hence, aforementioned results evident that the optimized sample endorse wide spread of applications, namely solid state lighting, high temperature dosimetry and advanced forensic science fields.

Rapid visualization of fingerprints on various surfaces using ZnO superstructures prepared via simple combustion route

Abstract A simple solution combustion route has been used to prepare ZnO nanopowders (NPs) using different barbiturates (Barbituric acid, 1, 3-dimethyl barbiturates and 2-thiobarbiturates) as fuels. The obtained product was well characterized by powder X-ray diffraction (PXRD), scanning electron microscope (SEM), ultraviolet-visible Spectroscope (UV-Vis) and Photoluminescence (PL). The PXRD results confirm the hexagonal phase of the material. The detailed structural analysis is performed by Rietveld refinement method. The energy band gap of NPs is found to be in the range of 3.31 - 3.49 eV. The growth mechanism for the formation of 3D micro-architectures is discussed in detail. The PL emission spectrum shows a broad emission peak at 502 nm upon an 406 nm excitation wavelength. The ZnO NPs can be used for the visualization of latent finger prints (LFPs) under normal light on various porous and non-porous surfaces. In this case, the visualized LFPs are found to be excellent compared to the commercially available powders.

Direct Z-scheme Cs2O–Bi2O3–ZnO heterostructures for photocatalytic overall water splitting

In this work, a direct Z-scheme Cs2O–Bi2O3–ZnO heterostructure without any electron mediator is fabricated by a simple solution combustion route.

Fabricated CeO2 nanopowders as a novel sensing platform for advanced forensic, electrochemical and photocatalytic applications

In Forensic investigation, identification of various types of ridge details are essential in order to fix the criminals associated in various crimes. Even though several methods and labeling agents are available to visualize latent finger prints (LFPs) there is still simple, accurate, cost-effective, and non-destructive tool is required. In the present work, CeO2 nanopowders (NPs) are prepared via simple solution combustion route using Tamarindus indica fruit extract as a fuel. The optimized NPs are utilized for visualization of LFPs on various surfaces by powder dusting method. Results revealed that visualized LFPs exhibit Level 3 features such as pores and ridge contours under normal light with high sensitivity and without background hindrance. The photometric characteristics of the prepared samples exhibit blue color emission and highly useful in warm light emitting diodes. The photocatalytic studies were carried out with different Methylene blue (MB) dye concentration and pH values. The obtained results reveal that the CeO2 NPs exhibits an excellent catalytic properties which can act as a good catalytic reagent. The findings demonstrate that the prepared NPs are quite useful as a labeling agent for visualization of LFPs, efficient catalysts for dye degradation as well as solid-state lighting applications.

Simple solution-combustion synthesis of Ni-NiO@C nanocomposites with highly electrocatalytic activity for methanol oxidation

Transition metal and its oxide composite nanomaterials are attracting increasing research interest due to their superior properties and extensive applications in many fields. In this paper, Ni-NiO@C nanocomposites were successfully synthesized in one step via a simple solution-combustion route, employing NiCl2 as the Ni source, oxygen in the atmosphere as the oxygen source, and ethanol as the solvent. The final product was characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), (high resolution) transmission electron microscopy (TEM/HRTEM), and Raman spectra. N2 gas sorption-desorption experiments uncovered that the BET surface area of Ni-NiO@C nanocomposites reached 161.9 m2 g−1, far higher than 34.2 m2 g−1 of Ni-NiO. The electrochemical measurement showed that the as-produced Ni-NiO@C nanocomposites presented better catalytic activity for the electro-oxidation of methanol than Ni-NiO and NiO, which provides a new catalyst selection for the electro-oxidation of methanol.

A comparative study on the structural, optical, electrochemical and photocatalytic properties of ZrO2 nanooxide synthesized by different routes

Nanooxide ZrO2 was synthesized by a simple solution combustion route utilizing urea as a fuel. For the comparative study, it has been additionally synthesized by sol gel route followed by calcination. The calcined ZrO2 nanaooxides were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), brunauer-Emmett-Teller (BET), electron paramagnetic resonance (EPR) and UV–Visible spectrophotometry analysis (UV–Vis). Both the photocatalytic activity and the photoluminescence (PL) properties of the synthesized ZrO2 intensifies depending on the crystallinity. The EPR analysis confirms the presence of paramagnetic defects in both the samples. SGR shows enlarged photocatalytic activity with 97% decomposition of Methylene blue dye beneath ultraviolet radiation. This work may expand our understanding on combining effects of defects, tiny crystalline size, narrowing energy band gap and giant surface areas of ZrO2.

A simple solution combustion route for the preparation of metal-doped TiO2 nanoparticles and their photocatalytic degradation properties

In this paper, we report the successful synthesis of metal ion-doped TiO(2) nanoparticles via a simple solution combustion method employing a mixture of ethanol and ethyleneglycol (v/v = 30/20) as the solvent, tetra-n-butyl titanate [Ti(OC(4)H(9))(4), TBOT] as the titanium source and oxygen gas in the atmosphere as the oxygen source, in the presence of small amounts of metal ions such as Cu(2+), Mn(2+), Ce(3+) and Sn(4+). The as-obtained products were characterized by means of powder X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS) and scanning electron microscopy (SEM). The UV-vis diffuse reflectance spectra (DRS) and photoluminescence (PL) spectra of various metal ion-doped products were investigated. Experiments showed that the metal ion-doped TiO(2) nanoparticles presented a stronger photocatalytic ability for the degradation of organic dyes, including Pyronine B, Safranine T and Methylene blue (MB), under visible light/254 nm UV light irradiation than commercial P25 within the same time.