Influence of Mg concentration on structural,morphological and optical properties of nanoceria

Nano crystalline pure and Mg doped ceriaparticles were synthesized by simple chemical co-precipitation method using cerium nitrate hexahydrate as a source material and magnesium nitrate as doping precursor at room temperature. The effect of doping were investigated by X-ray diffraction pattern(XRD), FT-Raman,fourier transform infrared spectroscopy(FTIR), Ultraviolet spectroscopy(UV), photoluminescence spectroscopy(PL), field emission scanning electron microscope(FESEM) and high resolution transmission electron microscopy with energy dispersive spectroscopy (HRTEM &EDS). The X-ray diffraction pattern and FT-Raman studies showed that the prepared samples were nano particulates with cubic fluorite structure. The XRD pattern analysis showed that the size of the particles ranged from 13 to 20?nm, however 4?wt% Mg doping results in reduction of particle size compared with other doping concentrations. The effects of Mg concentration on various structural parameters of the prepared samples were also determined. The slight blue shift observed upon doping in UV–Vis absorption region around 330–360nmrecorded for reduction in particle size. The FTIR unveils the presence of Metal oxygen bonds below 700?cm^?1in the prepared samples. All samples showed a broad emission band at 430?nm with linearly increasing intensity with respect to dopant concentrations. The Spherical morphology with weak agglomeration was identified through FESEM and HRTEM analysis. The elemental analysis of Ce, O and Mg were confirmed through EDS analysis.     

High acetic acid sensing performance of Mg-doped ZnO/rGO nanocomposites

Mg-doped ZnO/reduced graphene oxide (rGO) nanocomposites were synthesized using a facile and cost-effective sol-gel procedure to detect acetic acid vapor. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV–vis) diffuse reflectance spectroscopy, and photoluminescence (PL) analysis were utilized to characterize morphologies, compositions of the nanocomposites, and optical properties of the synthesized nanostructures. The gas sensing measurements of spin-coated Mg-doped ZnO/rGO thin films were carried out for a temperature range of 150–350?°C at various acetic acid vapor concentrations. It was found that the Mg-doped sample with 20?wt%/v of GO solution concentration exhibited the response/recovery time of 60?s/35?s with the best response of ~?200% for 100?ppm of acetic acid at 250?°C.     

Synthesis,characterization and enhanced visible-light photocatalytic activity of Zn2SnO4/C nanocomposites with truncated octahedron morphology

Novel Zn₂SnO₄/C nanocomposites with truncated octahedron morphology were constructed using a two-step hydrothermal synthesis route combined with subsequent calcination. The as-prepared samples were characterized by X–ray diffraction (XRD), Fourier transform infrared spectroscopy (FT–IR), Raman spectroscopy, field–emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), UV–vis diffuse reflection spectroscopy, photoluminescence spectroscopy (PL), and Brunauer–Emmett–Teller surface area measurements. The result of FESEM showed that the as-prepared Zn₂SnO₄/C nanocomposites are composed of numerous uniform nanoparticles with regular truncated octahedron morphology. Raman spectral characterization combined with HRTEM result revealed that a thin layer of carbon was attached on the surface of Zn₂SnO₄. Using rhodamine B (RhB) as a model organic pollutant, the visible-light photocatalytic activities of the as-prepared samples were investigated, and the photocatalytic mechanism was discussed. Compared with pure Zn₂SnO₄, Zn₂SnO₄/C nanocomposites exhibited much better visible-light photocatalytic activity. The increase in the photocatalytic activity of Zn₂SnO₄/C nanocomposites was mainly attributed to the enhancement of the optical absorption capability and efficient separation of photogenerated electron-hole pairs.     

Development of ZrO2‐MgO nanocomposite powders by the modified sol‐gel method

The ZrO₂‐MgO nanocomposites were synthesized using a new sol‐gel method with sucrose and tartaric acid as a gel agent. The samples were characterized by thermal analysis (TG/DTA), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy‐dispersive X‐ray mapping (EDX mapping), and Ultraviolet‐visible spectroscopy (UV‐vis). The results showed that the cubic phase of ZrO₂‐MgO was formed in the presence of both gel agents. The average particle size of the samples synthesized with sucrose was lower (30 nm) than that of tartaric acid (50 nm). Finally, the formation mechanism and the optical properties of zirconia‐magnesia have been discussed.     

Synthesis of Highly Crystalline Needle-Like Silicon Nanowires for Enhanced Field Emission Applications

Needle-like silicon nanowires (SiNWs) were successfully synthesized on gold-coated silicon substrates using a very high frequency plasma enhanced chemical vapor deposition method (VHF-PECVD). The prepared samples were characterized by field emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy (EDX), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and photoluminescence (PL). XRD analysis confirmed formation of single crystalline SiNWs along (111) crystalline planes and microscopic studies revealed formation of NWs with diameters ranging from 10 to 100 nm and lengths of a few micrometers. Furthermore, the presence of gold nanoparticles on the tip of the NWs verified the vapor–liquid–solid growth mechanism of SiNWs. It was also demonstrated that SiNWs are composed of well-crystallized silicon cores and an amorphous shell. The obtained results verified potential application of such structures in field emission displays.     

Electro-optical study of thermally stable PANI/lithium doped nickel oxide composites with enhanced photoluminescence properties

PANI/Lithium doped nickel oxide nanocomposites were synthesized via in-situ chemical oxidation polymerization method. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) used to study the strucurtal confirmation of synthesized composites. FESEM images showed the fabrication of nanocomposites in porous and nanofibers form. EDS is confirming the presence of constituent elements. Thermogravimetric analysis (TGA) of fabricated materials had the excellent thermal stability extended to higher temperature after doping in host matrix. Impedance analyzer has used to examine the electrical behaviors of synthesized composites. AC conductivity of synthesized composites were enhanced as compare to pure pani. Diffuse Reflectance Spectroscopy has used to study the optical characteristics of samples. Vibrating Samples Magnetometry results of composites depicts their superparamagnetic nature. In PL investigation, photoluminescence properties of affordable electro-optical fabricated materials were found to be improved at room temperature.     

Development of novel hybrid nanocomposites based on natural biodegradable polymer–montmorillonite/polyaniline: preparation and characterization

The problems with non-degradable materials in different applications have led to an interest in materials based on bionanocomposites. In this study, polymer–montmorillonite nanocomposites based on natural polymers (chitosan, alginate, gelatin and starch) and montmorillonite (MMT) were prepared using solution intercalation method. Then hybrid nanocomposites were synthesized by chemical oxidative polymerization of aniline in the presence of polymer–MMT nanocomposites. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) were employed to characterize the nanocomposites. FT-IR confirmed the successful preparation of hybrid nanocomposites. From the XRD results, intercalation of the MMT platelets in the matrix of polymers was examined. Further investigation by TEM images showed a mixed intercalated and flocculated structure for nanocomposites. Moreover, the TGA results showed improved thermal stability for the nanocomposites. The results presented in this study showed the feasibility of using these hybrid nanocomposites with improved properties in wide range of applications.     

Improved photocatalytic performance of Gd and Nd co-doped ZnO nanorods for the degradation of methylene blue

This paper reports the synthesis of pure ZnO, Gd and Nd co-doped ZnO nanorods based nanocomposites via simple hydrothermal method. Subsequently, the prepared photocatalysts were characterized using XRD, SEM/EDX, TEM, UV–visible and PL spectroscopy. The XRD results demonstrate that Gd and Nd ions were incorporated into ZnO lattice in the synthesized ZnO based nanocomposites and showed hexagonal wurtzite structure. The SEM and TEM results show that nanorods having nanoscale diameter and length were successfully synthesized by hydrothermal method. The UV–visible spectroscopy verified that the band gap of ZnO was reduced due to incorporation of Gd and Nd into ZnO photocatalyst. Similarly, Gd and Nd incorporation into ZnO was found effective to reduce the recombination of electrons and holes as confirmed by PL spectroscopy. Moreover, the prepared nanocomposites with various atomic ratios (0.5–2%) were tested for photocatalytic degradation of methylene blue (MB), under visible light irradiation. The highly efficient and optimized 1.5% Nd/ZnO nanocomposite demonstrated enhanced photocatalytic performance for the degradation of methylene blue compared to pure ZnO and other nanocomposites. Furthermore, the recycling results show that the 1.5% Nd/ZnO nanocomposites displayed good stability and long-term durability. These finding suggest that the ZnO based nanocomposite could be efficiently used in various energy and environmental applications.     

Ternary Ag@SrTiO3@CNT plasmonic nanocomposites for the efficient photodegradation of organic dyes under the visible light irradiation

In this research, carbon nanotube (CNT)-modified plasmonic silver-strontium titanate (Ag@ SrTiO₃) nanocomposites for the degradation of the organic dye were prepared by the sol-gel method. The characterization of all products was carried out using the X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), N₂ adsorption-desorption test (BET), field emission-scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV–visible diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, electrochemical impedance spectroscopy (EIS), and transient photocurrent (TPC) studies. It was found that the incorporation of Ag in and introducing CNT into the SrTiO₃ nanoparticles reduced the crystallite size to 21 nm and the band gap energy to 2.7 eV. The Reduced PL peak intensity, increased photocurrent value, and reduced charge transfer resistance approved that the Ag@SrTiO₃@CNT nanocomposite had a greater charge transfer efficiency than other samples. The optimal dosage of the photocatalyst, for the complete degradation of 5 ppm of the methylene blue (MB) solution after 30 min of the visible light irradiation, was decided as 0.5 g/L. Besides, in the experimental environment, the Ag@SrTiO₃@CNT sample illustrated the most significant photocatalytic performance of the degradation of methyl orange (MO) and Rhodamine B (RhB) dyes. The detailed mechanism and kinetics of the degradation procedure were clarified. Finally, the prepared system displayed increased stability and reusability in the entire cyclic degradation experiment.     

Bone Tissue Engineering of HA/COL/GO Porous Nanocomposites with the Ability to Release Naproxen: Synthesis,Characterization, and In Vitro Study

In the present research, porous hydroxyapatite/collagen/graphene oxide (HA/COL/GO) nanocomposites were synthesized using the freeze-drying method for naproxen delivery. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), and Brunauer–Emmett–Teller (BET) techniques were applied to analyze the synthesized specimens. In addition, the loading of naproxen and release behavior (pH 7.4 and T?=?37 °C) of the prepared nanocomposites were studied via UV–Vis spectrophotometry. The FE-SEM analysis revealed that HA/COL/GO nano-composites had a rod-like structure and the morphological change in the HA/COL/GO nano-composites confirmed that graphene oxide (GO) sheets and HA/COL nano-particles were successfully incorporated where the nanocomposites were synthesized with size smaller than 50 nm. BET analysis was utilized to confirm the meso and macrostructure of specimens with an average pore diameter within 15–103 nm as well as the BET surface area of 21–178 m²/g. The application of synthesized samples for naproxen delivery in vitro was investigated. As the weight ratio of GO increased, so did the percentage of drug-loading; for the HA/COL/GO-3 sample where the graphene oxide (GO) amount was maximum, the percentage of drug loading capacity (LC%) and percentage of encapsulation efficiency (EE%) were obtained 38.7% and 84.8%, respectively. Naproxen release results in phosphate buffer saline (PBS) confirmed that the initial release occurred in all synthesized nanocomposites within the first 24 h, after which the release rate gradually declined to about 14 days. Under optimal conditions, the HA/COL/GO-3 sample retained about 39.2% of the loaded drug after 14 days, as some of the drug molecules were deeply embedded in the HA/COL/GO-3 sample. Furthermore, the results revealed that the degradation rates of the synthesized nanocomposites can be controlled by adjusting the amount of graphene oxide (GO). Thus, the results show that the samples synthesized in this research can suitable candidates for continuous release of naproxen and bone tissue engineering.

     

Fe3O4/凹凸棒土磁性纳米复合材料的制备与表征

采用超声共沉淀法制备了Fe3O4-凹凸棒土(AT)磁性纳米复合材料,经红外光谱(FTIR),X射线衍射(XRD),场发射扫描电镜(FESEM),比表面积(BET)和振动样品磁强计(VSM)等方法进行表征.结果表明:Fe3O4纳米粒子较好地吸附在AT表面,并且表现出优良的吸附性能和顺磁性.     

Application of impregnation combustion method for fabrication of nanostructure CuO/ZnO composite oxide: XRD,FESEM, DRS and FTIR study

Nanostructured CuO/ZnO composite oxide was prepared by a novel impregnation combustion method using copper nitrate and zinc oxide tetrapod. The X-ray diffraction patterns revealed that CuO/ZnO composite oxide was formed. The effects of different impregnation combustion parameters on the properties of composite were studied by field-emission scanning electron microscope (FESEM), powder X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) and UV–vis diffuse reflectance spectrum (DRS). The synthesis of ZnO–CuO nanocomposites through impregnation of a zinc oxide tetrapod with copper nitrate aqueous sodium carbonate solutions is reported. During thermal treatment the samples evolve toward the formation of nanocrystalline ZnO particles (zincite phase) dispersed onto tenorite, CuO annealed at 450 °C. XRD patterns of the precursors calcined at 450 °C showed the formation of the zincite–tenorite phases. Field emission scanning electron microscopy (FESEM) exhibited loosely agglomerated hexagonal particles with uniform morphology having a size around 50 nm.     

Innovative preparation of bacterial cellulose/silver nanocomposite hydrogels: In situ green synthesis,characterization, and antibacterial properties

In this study, an innovative in situ green strategy was applied to prepare bacterial cellulose/silver nanocomposites using green tea as a substrate for the fermentation of Acetobacter xylinum bacteria and a reducing agent for the in situ synthesis of silver nanoparticles. The samples were analyzed by different characterization tests including field emission scanning electron microscopy (FESEM), X-ray diffraction analysis (XRD), UV–vis spectroscopy, atomic absorption spectroscopy, and ATR. The results indicated the excellent antibacterial activities with 100% bacterial reduction percentage and inhibition zones of 2.6 and 2.8 cm against S. aureus and E. coli, respectively. Moreover, water absorption percentage and vertical wicking measurements supported the hydrogel properties of the prepared bio-cellulose/silver nanocomposites. Finding of this research suggested the potential of the proposed green route for preparing antibacterial BC which can be regarded as a candidate for future wound healing applications.     

Synthesis and characterization of magnetic and fluorescent styrene co‐polymer nanofiber

F luorescent and magnetic poly(styrene) (PS) based random co‐polymer nanofiber was synthesized in a controlled manner via chemical polymerization in three steps. A fluorescent and magnetic nanohybrid {Fe₃O₄/Congored (CR)} was separately prepared and chemically grafted onto the epichlorohydrin (ECH) units of the random co‐polymer. Characterizations of the above synthesized polymers were done with the help of Fourier transform infrared (FTIR) spectroscopy, UV–visible spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, fluorescence emission spectroscopy, field emission scanning electron microscopy (FESEM), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) measurement, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and gel permeation chromatography (GPC) like analytical techniques. The FESEM results indicated that after the grafting of nanohybrid onto the random co‐polymer backbone, the polymer exhibited a nanofiber like morphology. Due to the surface functionalization and encapsulation reactions, the magnetic moment value of the nanohybrid and its nanocomposites were found to be reduced. Synthesis and characterization of magnetic and fluorescent random co‐polymer based nanofiber is the primary target of the present investigation and its application is extended to the catalysis field. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42796.     

Green synthesis of reduced graphene oxide supported TiO2/Co3O4 nanocomposite for photocatalytic degradation of methylene blue and crystal violet

The hybrid rGO-TiO₂/Co₃O₄ nanocomposite was successfully synthesized through co-precipitation method. The structural, morphological, compositional and optical properties of the as synthesized nanocomposite were characterized by X-ray diffraction (XRD), Field Emission scanning electron microscopy (FESEM), energy dispersive X-Ray Spectroscopy (EDS), Fourier transformation infrared spectroscopy (FTIR), UV–visible spectrophotometer (UV–vis) and photoluminescence (PL). XRD, EDS and FTIR confirms the existence of rGO-TiO₂/Co₃O₄ in the prepared nanocomposite. FESEM confirms that the TiO₂/Co₃O₄ nanocomposite are adsorbed on the surface of the rGO. UV–Vis and PL spectra revealed that the absorbance and emission occurred at visible region, which greatly supports the photocatalytic dye degradation through the electron-hole separation. The percentage decolorization of methylene blue dye solution was higher with lesser time compared to crystal violet dye. This result concludes that the commercialization of rGO/TiO₂/Co₃O catalyst may useful for treating various dyes in industries.     

Ag/αFe2O3-rGO novel ternary nanocomposites: Synthesis,characterization, and photocatalytic activity

In this research, novel ternary Ag/αFe₂O₃-rGO nanocomposites with various contents of GO were synthesized via a facile one-pot hydrothermal method. Ag/αFe₂O₃-rGO nanocomposites were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectrometer (EDX), photoluminescence (PL) spectroscopy, and Fourier transform infrared (FTIR). The results showed that hematite nanoparticles and Ag nanoparticles were well decorated on the graphene surface. Photocatalytic activity of Ag/αFe₂O₃-rGO ternary nanocomposites and pure Ag/αFe₂O₃ was investigated for photodegradation of Congo red dye solution as a model pollutant under UV light irradiation. The ternary nanocomposite with 1.8?mg/ml GO aqueous solution concentration shows higher degradation efficiency under UV light irradiation than the pure Ag/αFe₂O₃ and the nanocomposites with other GO aqueous solution concentrations. It was observed that the adsorption of the dyes on the nanocomposites surface is dependent on the graphene content due to a decrease in the recombination rate, particles size, and increase charge carrier transfer. The results show that the Ag/αFe₂O₃-rGO nanocomposite can be used as an excellent photocatalytic material for degradation of Congo red dye in wastewater. A possible photocatalytic mechanism was proposed for degradation of Congo red dye.     

Fabrication and characterization of CdS/BiVO4 nanocomposites with efficient visible light driven photocatalytic activities

Novel CdS/BiVO₄ nanocomposites were synthesized by simple solvothermal method. The as-prepared samples were characterized by transmission electron microscopy (TEM), scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Raman spectroscopy, UV–vis diffuse reflectance spectra (DRS), Fourier transform infrared spectra (FT-IR) and photoluminescence (PL). In the nanocomposites, CdS particles were deposited on the surface of the BiVO₄. The photocatalytic tests showed that the CdS/BiVO₄ nanocomposites possessed a higher rate for degradation of malachite green (MG) than the pure BiVO₄ under visible light irradiation. The 1.5-CdS/BiVO₄ nanocomposite photocatalyst was found to degrade 98.3% of MG under visible light irradiation. Moreover, the photocatalytic mechanism of CdS/BiVO₄ nanocomposites was also discussed. The results showed that the nanocomposite construction between CdS and BiVO₄ played a very important role in their photocatalytic properties, which has the potential application in solving environmental pollution issues utilizing solar energy effectively.     

利用超声法制备γ-Al2O3/7-羟基香豆素纳米复合发光材料

利用超声法,以7-羟基香豆素和γ-Al2O3纳米粉为原料,成功地制备出了γ-Al2O3/7-羟基香豆素纳米复合发光材料.测试结果表明:由于γ-Al2O3纳米粉和7-羟基香豆素之间的相互作用,所制得的复合材料的荧光强度明显高于原料本身的强度.此外,还研究了7-羟基香豆素溶液的浓度和超声处理的时间对复合材料荧光性能的影响.     

Influence of the addition of carbonated hydroxyapatite and selenium dioxide on mechanical properties and in vitro bioactivity of borosilicate inert glass

Five nanocomposite samples containing different percentages of carbonated hydroxyapatite (CHA), selenium dioxide (SeO₂) and inert glass (IG) have been prepared using high-energy ball milling method with the aim of improving the in vitro bioactivity of these nanocomposites. Fourier transform infrared (FTIR) spectroscopy along with X-ray diffraction (XRD) technique was applied on both nanopowders and the sintered nanocomposites to record the structural changes and examine the resultant sintered phases. Mechanical properties were measured by ultrasonic non-destructive technique. In order to assess the bioactivity of the sintered specimens, they were soaked in simulated body fluid for 14 days and then, they were investigated by FTIR and scanning electron microscopy (SEM). Both FTIR and XRD spectra showed that the glasses encouraged the partial HA decomposition to tricalcium phosphate (TCP) and calcium silicate (CaSiO₃) phases. The formation of the latter phase along with the remainder HA contents was responsible for good bioactivity and appropriate mechanical properties of the investigated nanocomposites. The successive addition of selenium dioxide to these nanocomposites led to further improvement of their bioactivity without any recorded changes in the mechanical properties. Based on the abovementioned results, the prepared nanocomposites can be used in various tissue-engineering applications.     

Comparative study of one-pot and facile methods to synthesize codoped CQDs with low band gap and photovoltaic properties

Three different one-pot methods of electrochemical, solvothermal, and pyrolysis were applied for the synthesis of nitrogen-doped carbon quantum dots (N-CQDs), N-F codoped carbon quantum dots (CQDs), and N-S codoped CQDs from monoethanolamine and citric acid precursors. Ammonium fluoride and/or thiourea were used as the precursors of the second dopant corporation. The effective synthesis parameters were studied on the basis of the factorial experimental design methodology to maximize absorption edge and reduce band gap in UV-visible spectroscopy. Among the best results, the synthesized N-F/CQDs prepared from ammonium fluoride and citric acid in monoethanolamine revealed the highest absorption edge of 650 nm, the band gap of 1.91 eV, and the particle size of 24 ± 7 nm using the pyrolysis method. The X-ray photoelectron spectroscopy (XPS) analysis indicated simultaneous doping of F and N atoms in the CQDs structure, and the photoluminescence (PL) analysis revealed excitation-dependent properties, which are effective for optical sensor and solar cell applications.