Facile Co-precipitation Route Research Articles

Structural, morphological and optical aspects of novel synthesized pristine and hafnium doped nickel oxide nanoparticles

The manuscript attempted to synthesise novel pure and Hafnium doped Nickeloxide (HNO) nanospheres using the facile co-precipitation route. Though the material is novel, a thorough enquiry on the structural, morphological and optical aspects of HNO is indeed and is carried out via various characterization techniques. The synthesis route guaranteed the production of nanosized spheres with reduced crystallite size was confirmed with structural and morphological studies. X-ray diffraction XRD) confirms the face centred cubic structure of NiO nanostructures, and it upholds the evidence of doping in NiO lattice. The morphological analysis was carried out with the scanning electron microscope (SEM) and transmission electron microscope, confirming the spherical NiO nanostructures and the effect of doping on its morphological properties. Furthermore, the UV analysis assessed the absorption spectra and the bandgap value is calculated using Kubelka–Munk plot. Moreover, PL analysis revealed that the doped samples exhibit a high bandgap above 3 eV and have strong emissions under 266 nm and 280 nm excitation wavelength.

Synthesis of hierarchical transition metal oxyhydroxides in aqueous solution at ambient temperature and their application as OER electrocatalysts

First-row (3d) transition metal oxyhydroxides have attracted increasing attention due to their various advantages. Although investigating the oxidation mechanism and processing such materials into hierarchical architectures are greatly desired for their further development, it remains unclear how the oxidation state change occurs, and efforts to produce hierarchical oxyhydroxides in compliance with high ecological and economic standards have progressed slowly. Here, we describe a facile one-step coprecipitation route for the preparation of hierarchical CoOOH, NiOOH and MnOOH, which involves the diffusion of NH3 originating from ammonium hydroxide solution into an aqueous solution containing metal ion salts and K2S2O8. Comprehensive characterizations by scanning electron microscope, transmission electron microscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy and in situ pH measurement demonstrated that K2S2O8 induces the oxidation state change of metal ion species after the start of hydrolysis. Meanwhile, it was found that, benefiting from the OH– concentration gradient created by the NH3 diffusion method and the suitable growth environment provided by the presence of K2S2O8 (high nucleation rate and secondary nucleation), the formation of hierarchical oxyhydroxide structures can be realized in aqueous solution at ambient temperature without the use of heat energy and additional structure-directing agents. The hierarchical CoOOH structures are performed as the electrocatalysts for the oxygen evolution reaction in alkaline media, which exhibit good activity with an overpotential of 320 mV at 10 mA cm−2 and a low Tafel slope of 59.6 mV dec–1, outperforming many congeneric electrocatalysts. Overall, our study not only provides important insights to understand the formation mechanism of hierarchical oxyhydroxides, but also opens up new opportunities for the preparation of hierarchical oxyhydroxides via a facile, green and low-cost method.

Study of structural and optical properties of europium ion activated bismuth oxide nanophosphors

The current study examines the structural and optical features of un-doped and a series of Eu3+ ion-doped bismuth oxide nanophosphors synthesized via a facile, low-cost, and room temperature co-precipitation route. X-ray diffraction (XRD) analysis confirms the monoclinic crystal structure without any trace of impurity. The FTIR spectroscopic analysis of the samples has been taken in 400–4000 cm−1 wavenumber range to analyze the bonding states and functional groups of the species. Optical properties of the samples have been investigated using UV–Vis and photoluminescence (PL) spectroscopy. We observed a slight increase in the band gap in the doped samples (2.79–2.81 eV) as compared to the bismuth oxide host (2.77 eV). The photoluminescence emission studies have been carried out under 466 nm excitation wavelength over the range of 550–750 nm. The most prominent peak in the emission spectra is observed at 612 nm corresponding to(5D0 → 7F2)transition of Eu3+ ion. An explicit augmentation in the emission intensity is observed in 7 mol% Eu3+ doped Bi2O3 nanophosphor. The emission spectra were used to calculate the CIE chromaticity coordinates and CCT of the phosphors. The CIE coordinates depict an evident red-shift in the Eu3+ doped phosphors. The CCT values have been sufficiently alleviated after Eu3+ doping. Thus, our study corroborates an evident red-shift in the aforementioned optimized composition and suggests that it is a potential candidate for lighting and display devices.

Fabrication of dual Z-scheme TiO2-WO3-CeO2 heterostructured nanocomposite with enhanced photocatalysis, antibacterial, and electrochemical performance

Direct dual Z-scheme heterostructured nanocomposite TiO2-WO3-CeO2 (NC) and pristine metal oxides nanostructures (NSs) were fabricated using a facile co-precipitation route. XRD, FTIR, and Raman data have confirmed the formation of NSs and NC. FESEM images showed quasi-mesoporous morphology of as-grown nanocomposite. EDX analysis confirmed the existence of titanium (Ti), cerium (Ce), and tungsten (W) in grown NC. The energy bandgap of NC was narrow 2.45 eV as compared to NSs. The higher electrical conductivity and lower recombination rate of NC were observed in IV and PL analysis. The photodegradation efficiency of NC was recorded 99.8% after 60 min under sunlight radiation against methylene blue (MB), which was significantly higher than NSs. NC catalyst has shown excellent photodegradation against other organic pollutants and has superior recyclability up to 7th cycle toward MB dye with a ~ 6% deficit in photodegradation efficiency. The antimicrobial activity results indicated the higher inhibition ability of NC against E. coli, K. pneumoniae, S. aureus, P. Vulgaris, and P. aeruginosa with maximum inhibition zone diameter 25, 29, 26, 28, and 27 mm, respectively. The electrochemical tests including CV, EIS, and GCD exhibited the superior capacitive behaviour of NC. These results demonstrate that grown NC is an efficient material for electrochemical devices, water purification, and biomedical applications.

Trace holmium assisting delaminated OMS-2 catalysts for total toluene oxidation at low temperature

In this study, octahedral molecular sieve (OMS-2) is successfully delaminated by using trace holmium (Ho) via a facile redox co-precipitation route, which exhibits high performance for the total toluene oxidation at low temperature. High resolution transmission electron microscope (HRTEM), X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) analyses verify that abundant multi-phase interfaces and lattice dislocations are formed on the obtained delaminated OMS-2 by the Ho (Ho-OMS-2), which can induce more active oxygen species. In particular, the delaminated OMS-2 with a trace Ho amount has a high Oads/Olatt ratio with a balanced ratio of Mn3+ and Mn4+, demonstrating much higher activity (T100% of 228 °C even under 5 vol% H2O vapor over 0.5% Ho-OMS-2) than the parent OMS-2 (T100% of 261 °C) for the total toluene oxidation. Furthermore, the positive effect of the introduction of H2O on catalytic activity, especially the enhancement of the conversion of intermediates into CO2 and H2O, is verified by the in situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS). Based on these results, the reaction mechanism for toluene oxidation over the OMS-2 based catalyst is proposed. It is expected to provide an effective preparation method to obtain high-performance catalysts for the VOCs oxidation at low temperatures.

Structural and thermal properties of pure and chromium doped zinc oxide nanoparticles

Pure ZnO and Cr-doped ZnO nanoparticles have been synthesized via a facile chemical co-precipitation route and their structural, thermal characteristics were discussed systematically. In the experimental producer, the doping concentration has varied the range, 0.05–0.1 M, while calcined at 600 °C. The influence of Cr-doping on the physical characteristics of ZnO nanoparticles was investigated and addressed. As-prepared samples were analyzed via XRD, FTIR, TGA/DTA, BET, and ICP-MS. XRD analysis shows that ZnO and Cr doped ZnO nanoparticles with average particle sizes between 23 and 39 nm were successfully developed with hexagonal wurtzite structure. The FTIR spectroscopy analysis confirms the existence of chromium in the doped ZnO nanoparticles and the formation of ZnO. The TGA/DTA analysis shows that Cr–ZnO nanoparticles are more thermally stable than ZnO nanoparticles. Moreover, the dopant concentration has been analyzed via ICP-MS and showed a good agreement with the expected chromium concentration. The BET surface area measurement shows that 176.25 m2/g and 287.17 m2/g for un-doped ZnO, and 0.1 M Cr-doped ZnO nanoparticles, respectively. Hence, doping of Cr enhances the surface area and thermal stability. Thus, Cr–ZnO nanoparticles show good thermal stability, and high surface area, which is an excellent characteristices of nanomaterials.Graphic abstract

A novel mesoporous Hydroxyapatite@Montmorillonite hybrid composite for high-performance removal of emerging Ciprofloxacin antibiotic from water: Integrated experimental and Monte Carlo computational assessment

The extensive use of persistent antibiotics to prevent human and animal infectious diseases has emerged as a global environmental concern. In this study, we report the effective removal of Ciprofloxacin (Cipro) antibiotic from aqueous solutions using a novel Hydroxyapatite@Montmorillonite (HAP@Mt) hybrid composite, which was synthesized via a facile co-precipitation route. The as-prepared HAP@Mt composite was thoroughly characterized by scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), transmission electron microscopy (TEM), N2 adsorption-desorption, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric and differential thermal analysis (TGA-DTA). The adsorption performance of HAP@Mt for Cipro antibiotic was investigated as a function of various physicochemical parameters. The Cipro adsorption process on the HAP@Mt composite was well described by pseudo-second-order kinetics and the Langmuir isotherm.The maximum uptake capacity reached 91.18 mg g−1. The Cipro binding mechanism was predominantly controlled by the electrostatic interactions, hydrophobic interactions, hydrogen bonding and n-π electron donor/acceptor interactions. HAP@Mt exhibited easy regeneration and excellent reusability for Cipro removal. Monte Carlo/SA simulations were performed to more clearly illuminate the atomic-level interactions between Cipro molecule and HAP@Mt surface under different pH conditions. The simulation data correlate well with actual results. The obtained experimental and computational findings provide new relevant insights on the application of HAP@Mt composite as a potential binder material to remove Cipro antibiotic from wastewater.

Hierarchical Co2SnO4 Microspheres for Enhanced NO2 Gas Sensing Performance

Introduction: The living standards of the human race in the past few decades have grown at a remarkable pace. One of the most critical environmental issues is the monitoring of air quality [1]. Nitrogen dioxide (NO2) is a hazardous gas and has multiple sources like vehicular emission, combustion process, and unvented heaters present in our day-to-day life. Overexposure to this gas becomes a reason for respiratory problems in humans as well as animals. Hence, it is very crucial to detect this toxic analyte selectively at low temperatures. Various metal oxides have been explored to detect NO2 gas; however, selectivity and operation temperature are still challenging [2]. Microsensors using nanostructured oxides/binary oxides are the most suitable to minimize the current problems of gas sensors (lack of sensitivity, selectivity, and stability) since the reduction in dimensions implies a greater contribution of the surface (greater sensitivity) as well as modification of the transport mechanisms (faster processes) [3-4]. This work demonstrates the low temperature, highly sensitive NO2 detection with fast recovery speed based on hierarchical Cobalt Stannate (Co2SnO4) microspheres synthesized by a facile co-precipitation route. Methodology: Hierarchical Cobalt Stannate (Co2SnO4) microspheres were synthesized with the co-precipitation method with a different annealing process. The sensor film was deposited on microsensors features an interdigitated electrode which encircled platinum heater to regulate the operating temperature and ensure its uniformity. The samples' structural and surface properties were characterized using X-ray diffraction (XRD), scanning electron microscopy (FESEM), and BET Surface area, especially to verify the nanomorphology and high surface area. Chemiresistive sensing behavior was recorded. The sensor response was calculated using the equation: Sensor Response (%) = (Ra-Rg)/Ra *100, where Ra and Rg are resistance in air and with the sensing gas, respectively. Results and Conclusions: Compared with the traditional metal oxide-based gas sensors, which operates at high temperature (>300 °C), specific accomplishments include (1) synthesis of Co2SnO4 microspheres with the larger surface area for higher sensing response towards NO2 gas; (2) chemiresistive gas responses of the Co2SnO4 sensor down to 1 ppm for NO2 at a low temperature of 90 °C with high sensitivity and long-term stability; (3) the morphology of microspheres for fast adsorption-desorption processes; and (4) the sensor shows the excellent reproducibility and reversibility with less power consumption (5) Co2SnO4 film exhibits a maximum sensor response of ~81 at 90°C towards NO2 with fast response (~ 24 s) and recovery time (~756 s) at one ppm. (6) the resulting sensor exhibits selectivity toward nitrogen dioxide compared to other gases such as CO2, CO, and H2.

Additive-free synthesis of BiVO4 microspheres as an electrochemical sensor for determination of antituberculosis drug rifampicin

The electrochemical sensor is a promising application that needs highly active materials for fabricating electrode of long cyclic stability, high surface area, low detection limit, excellent selectivity, and reproducibility. Herein, we successfully synthesized the bismuth vanadate microspheres via a simple additive-free facile coprecipitation method. Various spectral characteristic methods such as X-ray diffraction (XRD), Fourier transforms infrared (FT-IR), Raman, Ultra-violet diffractive reflectance spectroscopy (UV-DRS), and field emission scanning microscope (FE-SEM) analysis to examine the structural, surface morphology, and optical properties of as-prepared material. The electrochemical behavior of as-proposed bismuth vanadate modified screen-printed carbon electrode (BV/SPCE) was evaluated by the sensing of rifampicin (RF) through cyclic voltammetry (CV) and linear sweep voltammetry (LSV) systems. As a result, the oxidation peak current of BV/SPCE demonstrated good linearity with the linear concentration of RF ranges from 0.2 to 310 µM, and a low detection limit of 0.014 μM, respectively. The constructed electrode showed high selectivity against various organic and metal ions interference. The stability of the modified sensor exhibited excellent cyclic stability up to 100 cycles. The fabricated electrode was further detected to RF in human urine and serum samples with observed results are acceptable. The schematic illustration for the preparation of the BiVO 4 microspheres and its electrochemical detection of RF. • BiVO 4 microspheres were synthesized through the additive-free facile coprecipitation route. • BiVO 4 modified electrode displays a wide linear range of 0.2–310 µM with a low detection limit of 0.014 µM for the RF sensor. • The fabricated sensor offers excellent selectivity, reproducibility, repeatability, and cyclic stability towards the sensing of RF. • RF was successfully applied to real samples with satisfactory results.

Self-decoration of Barium Titanate with Rhodium-NP via a facile co-precipitation route for NO sensing in hot gas environment

There is an urgent need to develop real-time gas sensors capable of detection under hot-gas (>400 °C) flow, for applications such as exhaust emission control. In this context, Rh-doped BaTiO3 has been prepared by a co-precipitation route and heat-treated at 900 °C under 2 % hydrogen to obtain in-situ Rh-nanoparticle decoration of submicron BaTiO3 particles. X-ray diffraction, Raman, and X-Ray photoelectron spectrometry analysis confirm the presence of Barium Titanate phases and the substitution of Ti4+ by Rh3+. According to the analytic evidence, thermal hydrogen treatment leads probably to Rhodium diffusion out of titanate lattice, yielding a self-decoration of the nano-sized Barium Titanate particles. Further NO-sensing tests revealed that the sensors produced by deposition of this in-situ Rh-loaded BaTiO3 on the interdigitated electrodes (IDE) yield a significant increase of selectivity and response (∼18 % for 200 ppm NO) towards NO, for the first time, under a hot-gas environment reaching up to 900 °C as synthetic humid air being the carrier gas. The calculated response and recovery times are reasonable, and observed reproducibility confirms suitability to practical applications. Relying on the carried investigations, this good sensing performance can be explained by the creation of excessive oxygen vacancies resulting from Rhodium's surface diffusion. Moreover, it is to claim that excellent catalytic activity of Rhodium plays a key role in enhancing NO-sensing performance.

Fabrication and characterization of W-Ni nanocomposites via a facile chemical co-precipitation route

A novel method by combined chemical co-precipitation and hydrogen reduction was proposed in this work to synthesize nanopowders of W-10wt.%Ni. The morphology, microstructure and properties of the nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and transmission electron microscopy (TEM). It was found that the average grain size of NiW nanopowders were 18–40 nm. For evaluation of the thermal stability of the synthesized powders, further heat treatment under different temperatures were carried out, which demonstrated the addition of Ni influence the diffusion coefficient which leading to the variation of sintering structure. The form of NiW intermetallic compound inhibits the grain growth of nanopowder.

Controlled synthesis of palygorskite/Bi5O7I hybrid microspheres with high efficient photodegradation of antibiotics

Step-scheme (S-scheme) heterojunction is novel developed and has been demonstrated to be an efficient strategy to boost charge separation for the semiconductors with staggered band structure. Herein, 1D protonated palygorskite (denoted as Pal) nanofibers were introduced into Bi5O7I (denoted as BOI) nanosheets to fabricate 1D-2D Pal/BOI microspheres via a facile coprecipitation and calcination route. Series of characterization methods were employed to explore the structural composition, morphology and optical properties. The as-obtained 20 % Pal/BOI composite microspheres exhibited superior photocatalytic performance in the degradation of tetracycline hydrochloride (TCH) and ciprofloxacin (CIP) under simulated sunlight irradiation, which is 2.7 and 2.6 times higher than that of pristine Bi5O7I, respectively. In addition, photoelectrochemical characterizations were adopted to unveil the photocatalytic mechanism. The results demonstrated that the tight contact interface, hierarchical structure, improved optical response capbility and S-scheme heterojunction could efficiently accelerate spatial charge separation and migration, thus improving the photocatalytic activity. What’s more, the palygorskite played a vital role in the system to enlarge specific surface area, accelerate the charge separation and shorten charge transfer path under solar light irradiation. Such heterogeneous photocatalyst design strategy between bismuth-rich bismuth oxyhalides and natural clay might provide new insights for treating pharmaceutical wastewater.

Microwave absorption performance of Ni0.5Zn0.5Fe2O4 nanoclusters at 8.2–18 GHz frequency

The evolution of nanomaterials has significantly contributed to the advancement of smart and lightweight electromagnetic (EM) wave absorbing materials. In this study, Ni0.5Zn0.5Fe2O4 nanoclusters were synthesized by a facile co-precipitation route. The morphology, structure, phase, and chemical composition of the sample was investigated. Results show that the sample is composed of clustered Ni0.5Zn0.5Fe2O4 nanoparticles, wherein the nanoparticles clusters are composed of tiny individual particles with spherical morphology. Investigation of the EM wave absorption reveals that a composite of paraffin containing 20 wt% of the Ni0.5Zn0.5Fe2O4 nanoclusters absorbs a large percentage of the incident EM wave at a thin absorber thickness. The sample attains − 48.8 dB reflection loss at 14.42 GHz with a 3.0 mm thickness. The enhanced EM absorption performance can be ascribed to interface polarization resulting from the many active atoms on the surface of the Ni0.5Zn0.5Fe2O4 nanoclusters. These results show that the Ni0.5Zn0.5Fe2O4 nanoclusters can be used to effectively attenuate microwaves.

Facile co-precipitation route for magnesium ferrites nanostructure: Synthesis, influence of pH variation on structural properties

This report presents the synthesis of magnesium ferrite (MgFe2O4) by coprecipitation method and its subsequent characterization by using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. XRD results confirm the formation of single phase cubic spinel structure, having lattice constant from 8.3216 ? to 8.3252 ?. An infrared spectroscopy study confirms the presence of two main absorption bands indicating tetrahedral and octahedral group complexes, within the spinel lattice. We also report hopping length (LA and LB), strain (?) and dislocation density (?D) of ferrite sample.

BiOCl/cattail carbon composites with hierarchical structure for enhanced photocatalytic activity

Bismuth oxychloride (BiOCl) has great potential as a photocatalytic material. It is worthy to improve its photocatalytic performance by a simple and feasible method. In this work, withered cattail is carbonized directly at 800 ℃ in nitrogen atmosphere to obtain cattail carbon with good conductivity, which could be a good acceptor of photogenerated electrons. Through the one-step facile co-precipitation route with stirring at room temperature followed by the treatment of acetic acid, ultrathin nanosheets of BiOCl were synthesized and grew on the surface of cattail carbon. The BiOCl/cattail carbon composites have well-contacted heterojunction interface, hierarchical structure, high specific surface area and enhanced utilization of visible light, which allow the composites to separate the photogenerated electron-holes efficiently. Thus the BiOCl/cattail carbon composites could show excellent photocatalytic activity, which could remove rhodamine B completely within one hour under visible light. The degradation rate of the composite could achieve about 17 times higher than that of pure BiOCl. Mechanism test showed that both OH and h+ active species could work together to degrade organic pollutants. Therefore, our work combines readily available and inexpensive biochar materials with BiOCl, which provides a strategy for the low-cost synthesis of efficient BiOCl-based photocatalytic materials that can be used in large-scale industrial production to be applied in the treatment of organic wastewater.

A Novel Strategy to Obtain Hollow NaBiF₄:Yb3+/Er3+ Upconversion Nanospheres by One Step Coprecipitation.

Hollow upconversion luminescence nanomaterials have widespread applications in drug delivery, high efficiency catalysis, as well as energy storage owes to super-large specific surface area, cavity volume, and fluorescence properties. However, a series of complex processes and high temperature is required for the synthesis of these materials. Herein, a facile template-free coprecipitation route based on the Kirkendall diffusion process at room temperature had been developed to synthesize hollow NaBiF₄:Yb3+/Er3+ nanospheres with upconversion luminescence. X-ray diffraction (XRD), nitrogen adsoption/desorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and upconversion emission spectra demonstrated the successful preparation of NaBiF₄:Yb3+/Er3+ nanospheres with pervasive hollow morphology, relatively high specific surface area, and excellent upconversion luminescence properties. Moreover, the influence of some reaction parameters on the morphology and structure of the obtained samples were systematically explored. Additionally, the evolution mechanism of the hollow structure nanospheres was analyzed on account of the Kirkendall diffusion process related to the solid-liquid interfacial ion migration. It is expected that these hollow upconversion NaBiF₄:Yb3+/Er3+ nanospheres with upconversion luminescence prepared by this type of synthetic strategy will have widespread medical, environmental, and energy applications.

Electromagnetic properties of Cr-substituted nickel ferrite nanoparticles and their microwave absorption performance

Chromium (Cr) substituted nickel ferrite nanoparticle was fabricated via a facile coprecipitation route and the microwave absorption performance was investigated within 8.2–18 GHz range. Several characterization approaches have been employed to investigate the morphology, phase composition, chemical composition, and structure of the Ni0·5Cr0·5Fe2O4 nanoparticles. We observed that the nanoparticles are spherical, having compact arrangement and traces of inter-particle porosity. This suggests that the morphology would favor multiple transmission routes for the absorption of EM wave. Analysis of the sample's microwave absorption performance reveals that 20 wt percent loading of Ni0·5Cr0·5Fe2O4 nanoparticles in paraffin can effectively attenuate a large portion of EM wave within 8.2–18 GHz frequency range. The sample achieved an optimum reflection loss value −47.3 dB at 16.0 GHz at 2.5 mm thickness. The EM wave absorption observed can be credited to impedance match, interfacial polarization, and good dielectric/magnetic loss coupling. The absorption bandwidth of the sample covers the X-band and P-band frequency via tuning of the absorber thickness between 2.5 and 4.5 mm. These results show that the Cr-substituted nickel ferrite has good EM properties and can be considered as a possible EM wave absorbing filler.

Synthesis, characterization and investigation of photocatalytic activity of ZnMnO3/Fe3O4 nanocomposite for degradation of dye Congo red under visible light irradiation

ZnMnO3/Fe3O4 magnetic nanocomposites were fabricated via facile co-precipitation route and were calcined at 400 °C for 3 h. Synthesis of ZnMnO3/Fe3O4 magnetic nanocomposites were optimized by different weight percentages. Then, the as-synthesized sample was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), photoluminescence(PL), vibrating Sample Magnetometer (VSM), EDAX (Energy dispersive X-ray analysis), diffuse reflectance UV–Vis spectroscopy (DRS),ultraviolet–visible (UV–Vis) spectrometry, Bruner-Emmett-Teller (BET), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). Based on the results, elemental analyses of the samples were similar to those expected from the initial concentrations of the solutions used during synthesis. The x-ray diffraction pattern revealed that ZnMnO3/Fe3O4 has a cubic structure and average particle size of the catalyst was found 27.43 nm. In addition, Fourier transform infrared spectra could confirm the presence of hydroxyl group and Fe–O bond vibration in the catalyst. Further, the superparamagnetic behavior of the synthesized nanocomposite at room temperature was confirmed by VSM studies. Furthermore, the photocatalytic performance of ZnMnO3/Fe3O4 samples were evaluated based on the removal of Congo red (CR) in aqueous solution in 60 min of under visible light irradiation. The experiment demonstrated that 0.10 g of ZnMnO3/Fe3O4 nanocomposites can degrade (98.17%) 50 mg l−1 of Congo red (CR) solution. The mechanistic study using scavengers propose that the superoxide (O2·−) is the most reactive species involved in the photodegradation of organic dyes. The photocatalytic degradation of Congo red conformed the pseudo-first-order kinetic model and the rate constant achieved for 0.10 g l−1 of ZnMnO3/Fe3O4 was (k = 0.0384 min−1). Finally, the effect of reaction time, pH, and loading of ZnMnO3/Fe3O4 on degrading Congo red was studied. The synthesized ZnMnO3/Fe3O4 nanocomposite can be potentially applied as a magnetically separable photocatalyst to deal with water pollution problems.

Facile synthesis of Ce-doped SnO2 nanoparticles with enhanced performance for photocatalytic degradation of organic dye

Cerium (Ce)-doped tin dioxide (SnO2) nanoparticles (NPs) have been prepared by a facile hydrothermal coprecipitation route for photocatalytic decomposition of methyl orange (MO) dye. The as-obtained NPs were characterized using different physical methods. X-ray diffraction (XRD) analysis found a rutile-phase-like crystalline structure. X-ray photoelectron spectroscopy (XPS) revealed specific energies of 486.2 eV for Sn 3d3/2 and 497.4 eV for Sn 3d5/2 and confirmed an oxidation state of Sn4+. With increasing Ce concentration (from 0% to 2% and 4%), the optical bandgap energy of the SnO2 NPs reduced (3.4–3.1 eV), resulting in a red-shift that enhanced their photocatalytic activity. The 4% Ce:SnO2 NPs exhibited superior photodegradation performance against MO organic dye, achieving 94.5% decomposition in 100 min under exposure to ultraviolet–visible (UV–Vis) light. Indeed, the photocatalytic efficiency of the 4% Ce:SnO2 NPs was 4.9- and 2.44-fold higher than that of the bare SnO2 and 2% Ce:SnO2 NPs, respectively. This outstanding photodegradation efficacy of the as-obtained 4% Ce:SnO2 NPs was due to the effective doping of Ce into the SnO2 lattice, thus preventing the recombination and allowing the effective separation/migration of photoexcited charges (e−/h+). Furthermore, improved antibacterial activity against two bacteria was clearly observed when adding Ce dopant to the SnO2 NPs.

A novel Mn4+ doped oxyfluoride red phosphor for rapid-response backlights display.

An oxyfluoride red phosphor Cs2MoO2F4:Mn4+ was synthesized via a facile co-precipitation route with a certain molecular ratio of CsF and MoO3. X-ray diffraction analysis and its Rietveld refinement reveal that Cs2MoO2F4:Mn4+ crystallized in an orthorhombic structure with the Amam (63) space group. Upon blue light excitation, Cs2MoO2F4:Mn4+ exhibits a series of sharp red emission lines around ∼634 nm and the zero-phonon line (ZPL) is visible at 619 nm. The optimal doping amount of Mn4+ in Cs2MoO2F4 is 1.12%, and the decay curves show a good fit with the single exponential decay model. The fluorescence lifetime of the synthesized phosphors is relatively short and calculated as 3.18 to 2.46 ms, the Mn4+ ions in Cs2MoO2F4 experience a strong crystal field strength with a Dq/B of ∼4.87, and the distinct nephelauxetic ratio β1 is determined to be ∼1.0226. The thermal quenching mechanism of Mn4+ was also studied. Furthermore, by using the as-synthesized Cs2MoO2F4:Mn4+ phosphor as a red component and β-SiALON as a green light component, a WLED was fabricated with a high luminous efficacy of 114.70 lm·W-1 and wide color gamut of 109.1% of the National Television Standard Committee (NTSC) value. Hence, the Cs2MoO2F4:Mn4+ phosphor with a short fluorescence lifetime could potentially be an efficient red compensator for application in rapid-response backlight displays.