Facile Homogeneous Precipitation Method Research Articles

A facile homogeneous precipitation synthesis of NiO nanosheets and their applications in water treatment

NiO nanosheets were successfully synthesized by a facile homogeneous precipitation method with the assistance of ethanol amine. The sample was characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption–desorption techniques. The results demonstrated that the as-prepared product was cubic NiO nanosheets with a large surface area of 170.1m2g−1. Further, the as-prepared product was used to investigate its potential application for wastewater treatment. The maximum adsorption capacity for Cr(VI) and Congo red (CR) on NiO nanosheets has been determined using the Langmuir equation and found to reach up to 48.98 and 167.73mgg−1, respectively. It could be concluded that NiO nanosheets with special surface features had the potential as adsorbents for wastewater treatment.

Hierarchical Hollow Structure ZnO: Synthesis, Characterization, and Highly Efficient Adsorption/Photocatalysis toward Congo Red

Hierarchical hollow structure ZnO (CZ-400) was synthesized successfully by a facile homogeneous precipitation method. Morphology, structure, and optical properties of the as-prepared CZ-400 were characterized by different techniques. The mentioned product possessed hollow core and hierarchical shell morphology, and grew well-crystallinity with high surface area. The CZ-400 exhibited adsorption capacity and photocatalyst activity toward congo red (CR) higher than those of TiO2 P25 and commercial ZnO. This is attributed to the hierarchical structure of CZ-400, which provides the improved charge transport and the reduced recombination rate of photogenerated electron–hole pairs. In addition, the combinatorial effect of adsorption and photodegradation reflected the importance of adsorption in the enhanced photoreactivity. The results indicated that CZ-400 is a potential catalyst and adsorbent material for removal of CR from water samples.

Facile preparation of hierarchical hollow structure gamma alumina and a study of its adsorption capacity

The hierarchical shell and hollow core structure gamma alumina (γ-Al2O3) with high adsorption affinity toward organic pollutants was fabricated via a facile homogeneous precipitation method. The microstructure, morphology, and functional groups of the as-synthesized γ-Al2O3 were characterized in detail. The N2 adsorption–desorption measurement (BET) experimental result showed the surface area of γ-Al2O3 (Al90-600) is 320.6m2/g and the average pore size is 17.8nm. The effects of reaction parameters on the synthesis of hierarchical hollow structure were systematically investigated. The dye removal ability of this adsorbent was determined by batch adsorption procedure. The isotherms and kinetics of adsorption process were determined and analyzed in detail, which were found to obey the Langmuir isotherm model and the pseudo-second-order for both the Congo red (CR) and Methyl orange (MO). The maximum adsorption capacity of γ-Al2O3 for CR is 835.0mg/g, which is higher than that of many other previously reported hierarchical structured adsorbents. This facile synthetic approach is a very promising way for the design and synthesis of the typical hierarchical hollow structure materials with powerful adsorption capacity for the removal of organic contaminants from wastewater.

Preparation and characterization of ZnS:Tb,Gd and ZnS:Er,Yb,Gd nanoparticles for bimodal magnetic-fluorescent imaging

As bimodal magnetic-fluorescent imaging agents, the preparation of ZnS:Tb,Gd and ZnS:Er,Yb,Gd nanoparticles via a facile homogeneous precipitation method is reported. The results show that these nanoparticles are almost spherical in shape with a diameter of 100-200 nm approximately and a major phase of wurtzite-structured ZnS. The products can successfully label the human hepatocellular carcinoma (HepG2) cells and present low toxicity even at concentrations up to 5 mg mL(-1). Additionally, for the ZnS:Er,Yb,Gd nanoparticles calcinated above 950 °C, NIR-to-visible up-conversion fluorescence were obtained, which is believed to be superior to traditional ZnS-based bioimaging agents with down conversion. In MRI studies, they reveal a longitudinal relaxivity rate (r(1)) of 39.46 mM(-1) s(-1) and 57.8 mM(-1) s(-1), respectively, which are much larger than the conventional Gd-DTPA and currently reported Gd-base nanoparticles, suggesting great potential as MRI agents.

A promising new photocatalyst CdSnO3·3H2O for air purification under ambient condition

A new binary metal hydrate photocatalyst CdSnO3·3H2O was synthesized from Cd(CH3COO)2 and SnCl4·5H2O via a facile homogenous precipitation method. The photocatalytic activities of samples were evaluated by the photocatalytic degradation of volatile organic compounds (VOCs) in O2 gas stream under ultraviolet light irradiation. The results demonstrated that the typical CdSnO3·3H2O sample had an average particle size of about 16nm, a band gap of 4.4eV, and a specific surface area of 91.8m2g−1. The comparison of CdSnO3·3H2O synthesized at different pH values showed that the photocatalytic activities of CdSnO3·3H2O synthesized at pH 7 and 8 were higher than that of the samples synthesized at pH 6 and 9. Contrast to commercial P25-TiO2, the activity of this new photocatalyst was better. The conversion ratio of benzene was about 45% and 5%, corresponding to the mineralization ratio was about 60% and 25%, respectively. CdSnO3·3H2O also exhibited high photocatalytic activities towards cyclohexane and acetone. Then, the mechanism of the reaction on the new photocatalyst was discussed. Hence, the facile synthesis of this photocatalyst and its outstanding photocatalytic performance for VOCs are favorable to its potential application in the environmental remedy field.

A superior Ce-W-Ti mixed oxide catalyst for the selective catalytic reduction of NOx with NH3

A superior Ce-W-Ti mixed oxide catalyst prepared by a facile homogeneous precipitation method showed excellent NH3-SCR activity and 100% N2 selectivity with broad operation temperature window and extremely high resistance to space velocity, which is a very promising catalyst for NOx abatement from diesel engine exhaust. The excellent catalytic performance is associated with the highly dispersed active Ce and promotive W species on TiO2. The introduction of W species could increase the amount of active sites, oxygen vacancies, and Brønsted and Lewis acid sites over the catalyst, which is also beneficial to improve the low temperature activity by facilitating “fast SCR” reaction and enhance both of the high temperature activity and N2 selectivity simultaneously by inhibiting the unselective oxidation of NH3 at high temperatures.

Net-Like ZnO/Carbon–Aerogel Composite as Anode Material for Ni-Zn Secondary Battery

Nanosized ZnO particles were prepared by a facile homogeneous precipitation method. Resorcinol-formaldehyde sol with addition of the ZnO particles was carbonized at 700 °C for 1.5 h to prepare ZnO/carbon-aerogel composite. TEM investigation shows that ZnO particles were em-bedded in 3-dimensional net-like carbon and covered uniformly by amorphous carbon coating. Compared with ZnO, the ZnO/carbon-aerogel composite showed better cycling stability, higher discharge capacity and lower charge-transfer resistance. The discharge capacity delivered by the ZnO/carbon-aerogel composite remained above 550 mAh g-1during 40 cycles with little capacity loss. The enhanced electrochemical performances were mainly ascribed to the effects of the net-like structure of amorphous carbon, which uniformly surrounded the ZnO particles to guarantee good contact and acted as a skeleton to alleviate the shape change and dendrite growth of zinc electrode.

High sensitive and selective formaldehyde sensors based on nanoparticle-assembled ZnO micro-octahedrons synthesized by homogeneous precipitation method

Nanoparticle-assembled ZnO micro-octahedrons were synthesized by a facile homogeneous precipitation method. The ZnO micro-octahedrons are hexagonal wurtzite with high crystallinity. Abundant structure defects were confirmed on ZnO surface by photoluminescence. Gas sensors based on the ZnO micro-octahedrons exhibited high response, selectivity and stability to 1–1000 ppm formaldehyde at 400 °C. Especially, even 1 ppm formaldehyde could be detected with high response ( S = 22.7). It is of interest to point out that formaldehyde could be easily distinguished from ethanol or acetaldehyde with a selectivity of about 3. The high formaldehyde response is mainly attributed to the synergistic effect of high contents of electron donor defects (Zn i and V O) and highly active oxygen species (O 2−) on the ZnO surface.

Facile Synthesis of Multifunctional Nanocomposites with Tunable Luminescent and Magnetic Properties

A facile homogenous precipitation method has been developed for the synthesis of multifunctional, luminescent, and magnetic nanocomposites with Fe2O3 nanospheres as the core and europium-doped yttrium oxide (Y2O3:Eu3+) as the shell. The nanocomposites show both ferromagnetic behavior and excellent fluorescence properties with high emission intensity. The luminescent and magnetic properties of the multifunctional nanocomposites can be easily tuned by changing the synthesis conditions, which may find potential applications in biological fields.

Facile synthesis, growth mechanism and luminescence properties of uniform La(OH)3 : Ho3+/Yb3+ and La2O3 : Ho3+/Yb3+ nanorods

One-dimensional (1D) La2O3 and La2O3 : Ln3+ (Ln = Ho/Yb) nanorods have been successfully synthesized at a mild condition via a facile homogenous precipitation method followed a heat treatment of their corresponding hydroxides. It can be found that the type of alkali and dosage of urea play crucial roles in the formation of uniform lanthanum hydroxide nanorods. The lanthanum hydroxide nanorods are morphology-formative intermediate for the formation of lanthanum oxides nanorods. The possible formation processes of 1-D lanthanum hydroxide and oxide nanorods were investigated. Under ultraviolet light and low-voltage electron beam excitation, the as-prepared Ho3+-doped La2O3 nanorods show a strong green emission corresponding to 5S2 → 5I8 transition of Ho3+ ions, which possesses sharper transition lines in the green region and higher color purity than that of commercial ZnO : Zn phosphor. At the same time, La2O3 : Ho3+ nanorods have higher luminescence intensity than its bulk samples under the same excitation condition. Furthermore, green and red up-conversion emissions originating from two-photon ESA and ET are also observed from the La2O3 : Yb3+, Ho3+ nanorod samples.

Synthesis and bio-functionalization of multifunctional magnetic Fe(3)O(4)@Y(2)O(3):Eu nanocomposites.

A facile homogenous precipitation method has been developed for the synthesis of multifunctional, magnetic, luminescent nanocomposites with Fe(3)O(4) nanoparticles as the core and europium-doped yttrium oxide (Y(2)O(3):Eu) as the shell. The nanocomposites showed both super-paramagnetic behavior and unique europium fluorescence properties with high emission intensity. Their surface has been modified with a bifunctional ligand, p-aminobenzoic acid (PABA), and further biofunctionalized with biotin; the nanocomposites showed specific targeting for avidin-coupled polystyrene beads.