Facile Combustion Route Research Articles

Multifunctional smart engineering nano magnetic materials with ultrahigh synergetic adsorption-photocatalytic performance

Water contamination by organic dyes is a severe environmental and health issue requiring a sustainable remedial solution. Among different acid dyes, the Acid Violet-19 (AV-19) extensively used for the coloring of fabrics has toxic and carcinogenic effects, which need to be effectively treated with state-of-the-art photocatalysts and techniques. In the present work, a series of nanomagnetic spinel ferrites (MFe2O4: M = Mg, Ca, Mn, Ni, Zn, and Cd) were synthesized for dye remediation through a facile combustion route. The synthesis involved the pioneering use of DL-Glutamic acid as a fuel due to low ignition temperatures (200–250 °C), cost-effectiveness, and environmental compatibility. The nanomagnetic particles with d90 < 200 nm and crystallite sizes lower than 50 nm were synthesized, exhibiting strong superparamagnetic properties and high surface areas. The synthesized nanoparticles exhibited ultrahigh adsorptive elimination and superior photocatalytic degradation of AV-19 under high concentration (250 and 100 mg/L) conditions. High monolayer absorbance capacities of 3905, 1061, and 814 mg/g were achieved for CaFe2O4, MgFe2O4, and CdFe2O4. The AV-19 elimination is well described by the Langmuir isotherm and second-order kinetic model. The dipole-dipole and Yoshida H-bonding interactions are the proposed adsorption mechanisms. The ZnFe2O4 showed exceptionally high photocatalytic dye degradation (∼ 100 % within 1 h), with the first-order kinetic rate constant being 0.063 min−1 at a photocatalyst dose of 0.1 g/L. The synthesized catalyst also showed high removal-degradation efficiency against different cationic and anionic dyes, including Malachite green, crystal violet, and Titan yellow. The solution pH showed an insignificant effect on the synergetic adsorption and photocatalytic degradation efficiency of MFe2O4. The present study shows that synthesized magnetic nanoparticles through the facile combustion route effectively eradicate the dye pollutants from wastewater.

Tailoring the structure-morphology-vibrational-optical-dielectric and electrical characteristics of Ce@NiO NPs produced by facile combustion route for optoelectronics

Nickel oxide is found to have a wide-range of applications in opto-electronic fields. So, we have synthesized the NiO with 0, 1, 2.5, 5 and 7.5 wt% Ce ion through one pot flash combustion route facilely at 450 °C and subjected to various state of art-excremental studies. Structural study points out that the major phase is belongs to cubic NiO, however, low intensity peaks were observed for cubic CeO2 as well. Hence, it confirms the Ce doping in NiO. This was further confirmed from FT-Raman spectroscopy analysis in which the extra vibrational mode at 450 ± 5 is belongs to Ce2O at higher content of Ce. Further confirmation of Ce presence and its homogeneity in the final product was approved through energy dispersive X-ray spectroscopy/e-mapping measurements. The morphological investigation was done by SEM and Field emission-SEM which confirm the formation of low dimension nanoparticles of size within the range of 41–75 nm. Diffused reflectance spectra were used to obtain energy gap using Kubelka-Munk relation and noticed in range of 3.42–3.55 eV for NiO@Ce NPs. Frequency dependent dielectric and electrical properties were also studied and discussed in detail.

Controlled synthesis of (CuO-Cu2O)Cu/ZnO multi oxide nanocomposites by facile combustion route: A potential photocatalytic, antimicrobial and anticancer activity

Photocatalytic activity of (CuO-Cu2O)Cu/ZnO hetero-junction nanocomposites along with their luminescent, biological applications in the progress of anticancer and antibacterial agents is investigated. The Cu and Zn bi-components modified (CuO-Cu2O)Cu/ZnO nanocomposites were synthesized via facile combustion route in the presence of controlled fuel to oxidizer ratio and were characterized by X-Ray Diffraction (XRD) patterns, Transmission electron microscopy (TEM), High resolution Transmission electron microscopy (HRTEM), Scanning Electron Microscopy (SEM), X-ray photoelectron Spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL) and energy dispersive X-ray (EDX) analysis. The PL and UV–Visible diffused reflectance spectral (UV–Vis-DRS) techniques were used to measure the optical sensitivity and tuning of band gap in the samples. The excellent photocatalytic degradation of Methylene Blue and industrial waste water under Sunlight irradiation depends on the mass ratios of Cu/Zn. The findings show that the addition of a certain proportion of CuO, Cu2O, ZnO, and Cu can promote efficiency in Sunlight harvesting and separation of charge carriers. Process parameters namely catalyst quantity, dye concentration and a proposal for the mechanism of degradation pathway, experiments for trapping and enhancer are investigated. The study of photoluminescence, CIE and CCT calculations suggests that the present nanocomposite may find applications as phosphor material in warm white LEDs. The second segment of this study deals with the investigation of antibacterial performance of composites upon Gram-negative and Gram-positive bacteria. The results indicate that nanocomposites can be used in antibacterial control systems and as an important growth inhibitor in various microorganisms. The cytotoxic effect of the (CuO-Cu2O)Cu/ZnO (CCCZ11) nanocomposite was determined by colorimetric and flow cytometric cell cycle analysis. Our experimental results show that the nanocomposite can induce apoptosis and suppress the proliferation of HeLa cells. The applications of nanocomposites based on Cu, an abundant and inexpensive metal has created much interest in various multifunctional applications.

Aluminium and cerium co-doped ZnO nanoparticles: Facile and inexpensive synthesis and visible light photocatalytic performances

Facile combustion route synthesized Al and Ce co-doped ZnO nanoparticles photocatalysts were characterized using XRD, SEM, BET, EDS, UV-visible DRS, PL, photocurrent and EIS techniques. XRD and SEM analyses identify that crystallite and particle size is reduced from 13.26 to 11.88 nm with introduction of Al and Ce into ZnO which assists inhibiting the recombination of photo generated charge carriers. UV-visible DRS spectra indicate that optical assimilation of ZnO is significantly increased to visible region (∼406 nm) and band gap reduces from 3.18 to 3.06 eV with introduction of Al and Ce co-dopants. Electrochemical impedance spectroscopy analysis under visible light illumination confirms the enhancement in visible light activity of Al and Ce co-doped ZnO nanoparticles as photocatalysts. The enhanced activity of Al and Ce co-doped ZnO photocatalyst can be ascribed to enhanced light assimilation, high surface area and efficient charge transfer process. Our results reveal that by incorporating precise amount of Al (∼2%) and Ce (∼2%) into ZnO, a highly efficient catalyst can be synthesized that have degraded almost 95% methyl orange (MO) dye in just 45 min. Further, the influence of various operational parameters such as solution pH, catalyst dose, dye concentration, airflow rate and light intensity on photodecomposition of MO was evaluated. Furthermore, a possible mechanism for Al and Ce modified ZnO was proposed and designed photocatalysts demonstrates good stability in aqueous medium.

Study of Structural and Photocatalytic Activity of Cobalt Doped Nanocrystalline Gadolinium Aluminate via Facile Combustion Route

Up converting (UC) nanoparticles have been a milestone for the people of optical world in the past decade because of their extraordinary properties. In this article, a novel cobalt doped nanocrystalline Gadolinium Aluminate (GdAlO3:Co2+) have been successfully synthesized by the solution combustion method. The structure of the samples were characterized using X-ray diffractometer (XRD) shows that transition metal (TM) doped nanoparticles have smaller crystalline size the structural morphology was studied using Transmission electron microscopy (TEM) which shows irregular shaped, highly dispersed and the size was found to be in the range of 15–25 nm. The result demonstrated that the synthesized material could be useful for dye decolourisation as a photocatalyst.

Combustion synthesis, characterization and photocatalytic application of CuS/Bi4Ti3O12 p-n heterojunction materials towards efficient degradation of 2-methyl-4-chlorophenoxyacetic acid herbicide under visible light

In this study, a series of CuS/Bi4Ti3O12 p-n heterojunction materials were synthesized by a two-step process. Initially, the Aurivillius phase Bi4Ti3O12 (BT) was synthesized by a facile combustion route using urea as a fuel. The Bi4Ti3O12 was subsequently modified by deposition of CuS (5–20 wt%) using a hydrothermal route to prepare the heterojunction materials. The methods of synthesis and calcination temperature were important factors which influenced the morphology, particle size and phase purity of Bi4Ti3O12 material. Phase pure BT nanoplates with planar dimension of 150–200 nm and thickness between 50 and 70 nm were obtained at a calcination temperature of 600 °C. Pure CuS prepared by hydrothermal method, contained hierarchical microspheres with diameter in the range of 1.2–1.6 μm. The heterostructure materials exhibited hierarchical flower like structure consisting of ultrathin CuS nanosheets and BT-nanoflakes. HRTEM and microstructural study revealed microscopic close interaction between the two phases. The optical and electrical measurement study suggested significant improvement in visible light absorption (400–800 nm) and charge carrier separation due to heterojunction formation. The CuS/Bi4Ti3O12 materials showed excellent photocatalytic activity for aqueous phase degradation of 2-methyl-4-chlorophenoxyacetic acid (MCPA) herbicide under visible light (>95% degradation in 3 h). The rate constant for CuS/Bi4Ti3O12 materials was 4.5 times higher than the pure BT material towards MCPA degradation. The OH and O2– radicals have been identified as the reactive species, the formation of which was confirmed by spectrometric method using terephthalic acid and nitroblue tetrazolium as molecular probes. The mechanism of MCPA degradation over the photocatalyst surface has also been elucidated using LC-ESI-MS, TOC and scavenger experiments.

Photoluminescence Studies of Rare-Earth-Doped (Ce3+) LaAlO3 nanopowders prepared by facile combustion route

A green emissive with a CIE coordinate (0.179, 0.415), Ce3+ doped Lanthunum alluminate (LaAlO3) rhombohedral phosphor was prepared by solution combustion synthesis with crystallite size in the range 20-50 nm and characterized by PXRD, TEM, Uv-Visible and photoluminescence. Optical band gap of Ce3+ doped LaAlO3 was estimated to be in the range 2.94-4.99 eV. LaAlO3:Ce3+ was effectively excited by NUV and characteristic PL emission confirms that, the phosphor can be a candidate for display applications.

Catalyst-Free Synthesis of Hollow-Sphere-Like ZnO and Its Photoluminescence Property

Hollow-sphere-like ZnO was successfully prepared by a facile combustion route at 950°C, and no external catalysts or additives were introduced. The morphology and structure of the hollow-sphere-like ZnO were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and energy dispersive spectrometer (EDS). The possible growth mechanism was discussed in detail. In addition, the as-obtained hollow-sphere-like ZnO exhibited a strong green emission at 518 nm and a weak UV emission at 385 nm. We believe that the hollow-sphere-like ZnO material may be a good candidate for application in optical devices and catalyst systems.

Facile Combustion Route for Low-Temperature Preparation of Sr2SiO4:Eu2+ Phosphor and Its Photoluminescence Properties

Uniform and nanosized phosphors of Sr2SiO4:Eu2+ were successfully synthesized by a simple, inexpensive, and relatively low-temperature synthesis route using the combustion method. Through the chemical reaction of Sr(NO3)2, Eu(NO3)3, and fumed silica, the pure phase of nanosized Sr2SiO4:Eu2+ was obtained by sintering at 800 °C for 3 min. The crystallinity and morphology of the as-synthesized Sr2SiO4:Eu2+ powders were characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The particle size of the Sr2SiO4:Eu2+ powders was distributed in a range of 30–50 nm. Furthermore, their photoluminescence and luminescence decay properties were also systemically discussed and compared with those of Sr2SiO4:Eu2+ phosphor prepared by a conventional high-temperature solid-state reaction method. The luminescence decay curves indicated that the distribution of Eu2+ ions in the nanosized Sr2SiO4 powders was in a nearly homogeneous average local environment.