Characterization of iron(III) oxide nanoparticles prepared by using ammonium acetate as precipitating agent

The effect of precipitating agent on the preparation of iron(III) oxide particles was investigated. Iron(III) oxide particles were prepared by precipitation of aqueous ferric nitrate solution by using ammonium acetate and ammonium hydroxide as precipitating agents. Particle size, shape, chemical composition, crystalline formation rate, crystallinity and magnetic property were measured for Fe₂O₃ particles obtained by precipitating with ammonium acetate, and compared with those of particles formed by using ammonium hydroxide. TGA, DTA, IR, XRD, TEM and VSM were used to characterize the particles. The nanoparticles synthesized with ammonium acetate showed a narrow size distribution, spherical shape, fast crystalline formation rate, high crystallinity and complete hysteresis loop. The better properties of particles formed by using ammonium acetate were originated from the chelating effect of carboxylate ions and higher crystallinity than those synthesized with ammonium hydroxide.     

Synthesis of spherical NiO nanoparticles using a solvothermal treatment with acetone solvent

Nanometer-sized nickel oxide (NiO) particles were synthesized by thermal reactions with nickel (II) carbonate as a metal-containing precursor and four solvents: water, ethanol, butanol, and acetone. The optimal reaction conditions to obtain spherical NiO were determined to be the acetone solvent, nickel carbonate precursor, and a reaction temperature and time of 200 °C and 48 h, respectively. TEM images revealed perfectly spherical NiO nanoparticles of size ranging from 2.0 to 10.0 nm in the acetone solvent. The reaction mechanism for the formation of the NiO nanoparticles is proposed based on a pathway of chelated Ni complex during crystal growth. Although metallic Ni was also formed from reactions using the two alcoholic solvents, the Ni(OH)₂ structure remained in the water solvent after thermal treatment.     

均匀沉淀法制备纳米氧化镍及其工艺优化

为研制生物质气化用纳米N iO催化剂,文中以六水合硝酸镍为原料、尿素为沉淀剂,采用均匀沉淀法制备了纳米N iO,并利用TGA,XRD,TEM等分析手段对前驱体和产品的性能进行了表征。同时,探讨了制备条件对产品粒径和产率的影响,得出了最佳工艺条件:反应物n(六水合硝酸镍)/n(尿素)=1∶3,沉淀反应温度和时间分别为115℃和2.5 h,煅烧温度400℃,煅烧时间1 h。最佳条件下所得纳米N iO粒子呈球形,分散性好,纯度较高,属立方晶系结构,平均粒径约为7.5 nm。     

Influence of temperature,ripening time and calcination on the morphology and crystallinity of hydroxyapatite nanoparticles

Nano-sized hydroxyapatite (HA) particles were prepared by chemical precipitation through aqueous solutions of calcium chloride and ammonium hydrogenphosphate. The influence of temperature, ripening time and calcination on the crystallinity and morphology of the HA nanoparticles were investigated. It was found that the crystallinity and crystallite size increased with the increase of synthetic temperature and ripening time. XRD and TEM results showed that the morphology change of HA nanoparticles was related to their crystallinity. High crystallinity of HA led to regular shape and smooth surface of the nanoparticles. The crystallinity of HA powders increased greatly after calcination at 650 °C for 6 h but the change of the crystallite size after calcination was dependent on the crystallinity and crystallite size of “as prepared” HA nanoparticles.     

超增溶自组装制备纳米氧化镍

采用超增溶自组装合成了纳米氧化镍,并通过透射电镜（TEM）、X射线衍射（XRD）、N2吸附脱附BET法和热重分析（TG）表征了其结构。结果表明,形成的纳米粒子分散性良好,粒径分布较窄(10～20 nm),晶粒度良好,微晶晶化比较完全,氧化镍纳米粒子具有较大的孔径,比表面积和孔容符合纳米粒子特性。确定了超增溶自组装制备纳米氧化镍的最佳工艺条件。     

纳米氧化镍制备及表征

以六水硝酸镍和氨水为原料,采用配位均匀沉淀法制备了纳米氧化镍。探讨了制备条件对氧化镍前驱体产率和纳米氧化镍平均粒径的影响,得出最佳工艺条件：镍离子浓度为0.8 mol/L,反应物配比［n（氨水）/n（硝酸镍）］为3∶1,沉淀反应温度为80 ℃,反应时间为90 min,焙烧温度为400 ℃,焙烧时间为1 h。同时,利用X射线衍射（XRD）和透射电镜（TEM）等分析方法对产品组成和形貌进行了表征,结果显示,实验制得的氧化镍纳米晶属标准面心立方晶系结构,晶粒呈球形,平均粒径约为12 nm。     

Phytoextract assisted hydrothermal synthesis of ZnO–NiO nanocomposites using neem leaves extract

This work represents the synthesis of zinc oxide nanorods, nickel oxide nanoparticles, and zinc oxide-nickel oxide nanocomposites by combining Neem leave extract with hydrothermal synthesis. Five samples were prepared by green synthesis which is based on Neem leaves aqueous extract followed by hydrothermal treatment at 250 °C for 2.5 h. The five prepared samples are: 100% NiO (N100), 75% NiO: 25% ZnO (Z25-N75), 50% NiO: 50% ZnO (Z50-N50), 25% NiO: 75% ZnO (Z75-N25), and 100% ZnO (Z100). The prepared nanoparticles and nanocomposites were characterized by FTIR, XRD, SEM, and TEM. The XRD results show that the ZnO formed as a hexagonal wurtzite phase and NiO as a cubic phase. The microstructure of the formed samples is versatile with nanorods ZnO and spherical NiO. The nanocomposites microstructure appears as a heterostructure of both oxides with NiO particles on the surface of ZnO rods. The TEM confirms the nanosize and the crystallinity of samples.     

Phytoextract-mediated synthesis of Cu doped NiO nanoparticle using cullon tomentosum plant extract with efficient antibacterial and anticancer property

In the present study, nickel oxide (NiO) and copper-doped nickel oxide (NiCuO) nanoparticles (NPs) were successfully synthesized using Cullen tomentosum plant extract with the co-precipitation method. This work focuses on the Phyto-mediated synthesis and characterization of NPs for their biological applications. Phytochemicals that exist in the plant extract acts as reducing and capping agent. The successful formation of the NPs was validated by various analysis as XRD, FESEM, EDAX, FT-IR, UV–Vis, and Photoluminescence. According to XRD studies, the average crystallite size of NiO and NiCuO NPs is 36 nm and 31 nm, respectively. The river stone and nanoflower like morphology for NiO and NiCuO NPs are confirmed by FESEM image. Furthermore, the synthesized NPs were tested against Gram-positive (Bacillus subtilis, Streptococcus pneumoniae) and Gram-negative (Klebsiella pneumoniae, Escherichia coli) bacteria, which showed enhanced antibacterial activity of NiCuO NPs. The cytotoxicity of NPs was investigated against human breast cancer cells (MDA-MB-231) and fibroblast L929 cell lines. Also, the IC₅₀ value for human breast cancer cells is 11.8 μg/mL. According to these findings, NiCuO NPs are potential nanomaterials with advanced healthcare uses.     

Controllable Synthesis of NiSe<Subscript>2</Subscript> Nanostructures via Hydrothermal Process for Photocatalytic and Solar Cell Applications

This paper reports on the synthesis of rice-like NiSe₂ nanoparticles via a simple hydrothermal method by employing [bis(2-hydoxyacetophenato)nickle(II)], [Ni(HAP)₂], as a novel nickel precursor. Effect of nickel source on morphology and size of nanostructures was also investigated. Moreover, the as-synthesized NiSe₂ nanostructures were utilized as the photocatalyst for the degradation of methylene blue (MB) and as the counter electrode in dye-sensitized solar cells. The results showed that structures size and morphology have salient effect on solar cells and using rice-like NiSe₂ nanoparticles leads to an increase in DSSCs efficiency compared to agglomerated sphere-like particles from 6.04 to 8.99?% (~49?% improvement).     

Effects of solvents on properties of nanocrystalline hydroxyapatite produced from hydrothermal process

Hydroxyapatite (HA) particles have been synthesised in isopropanol–water solvent via hydrothermal process. The influences of isopropanol on crystallisation, such as phase evolution, crystallite size, crystallinity degree, chemical composition, and agglomeration of the HA nanoparticles have been investigated by using XRD, FTIR, TEM, BET, TG-DSC and laser diffraction method. All HA nanoparticles prepared in the water–isopropanol mixed solvent have been found to be carbonated HA, and the amount of carbonate increased with increase of alcohol in the solvent. However, the crystallite size and crystallinity degree of the HA nanoparticles decreased with the addition of isopropanol. In addition, there was little change in morphology of HA particles produced in different solvents, though the aspect ratio of the HA increased slightly with increasing concentration of alcohol. The agglomeration was found to be mainly controlled by the zeta-potential and not by the change of solvent.     

超临界水快速连续制备纳米磷酸铁锂正极材料

建立了超临界水快速连续合成磷酸铁锂纳米颗粒的工艺。研究了反应物浓度、反应温度和反应压力等因素对磷酸铁锂颗粒的大小、结晶度和形貌的影响并解释了相关机理,采用扫描电镜（SEM）、动态光散射（DLS）粒度分析和X射线衍射（XRD）等手段表征了目标产物的颗粒大小、形貌和结晶度。结果表明,在所研究的过程参数范围内,均获得了纳米尺度的磷酸铁锂。在超临界范围内,提高反应温度会使颗粒尺寸变大,但粒度分布更加均匀;预热温度对磷酸铁锂的结晶度有明显的影响,升高预热温度有利于提高磷酸铁锂纳米颗粒的结晶度;较高的反应压力、较低的反应物浓度有利于得到更小的纳米颗粒。在反应温度为380 ℃、预热温度为405 ℃、反应压力为27 MPa、二价铁离子浓度为0.015 mol/L条件下,获得了平均粒度为105 nm的高结晶度、橄榄石状的球形磷酸铁锂颗粒。     

Novel synthesis and antimicrobial studies of nanoscale titania particles

In the present investigation, a novel strategy of continuous microwave assisted flow synthesis (CMFS) has been adopted in comparison to traditional synthesis procedures (sol-gel and chemical precipitation method) for the quick production of TiO₂ nanoparticles with very fine particle properties. The X-ray powder diffraction analysis (XRPD) and transmission electron microscopy (TEM) were two techniques used for analysing the properties related to structure and particle morphology of the resultant samples. It was observed that the particles formed by using continuous flow route were less agglomerated, and particle size (~ 6?nm) was smaller in comparison with others obtained using sol-gel (~ 9?nm) and chemical precipitation method (~ 15?nm). X-ray diffraction impressions established the generation of Anatase phase with preferential [101] dimension. Zeta potential computations were taken to inspect the colloidal stability of nanoparticles. Antimicrobial nature of TiO₂ nano-samples was analyzed by using various bacterial and fungal strains. The nanostructured TiO₂ particles confirmed outstanding uniformity with respect to chemical and structure. This new ceramic substance with strong antimicrobial activity promised magnificent potential in bone tissue engineering.     

Preparation of Mn3O4 by precipitation conversion-roasting method and its morphological evolution

This study reports the fabrication of micro-sized spherical Mn₃O₄ particles using a precipitation conversion-roasting method. Morphological evolution of the product and mechanism of formation have been investigated. The results showed that the amount of alkali used in the precipitation conversion step had a significant effect on the morphology and particle size of the product. When mole ratio of the alkali to manganese increased from 1.6 to 4.0, morphology of the Mn₃O₄ precursor gradually evolved from an irregular cubic shape to a regular spherical shape, and finally, a regular cubic shape with uniform particle size. According to transmission electron microscopy (TEM) and selected area electron diffraction (SAED), morphological evolution of the Mn₃O₄ precursor was caused by the preferred orientation of crystal planes and supersaturation of the reaction system. Scanning electron microscopy (SEM) images of samples before and after calcination showed that morphology of precursor was inherited by the product obtained after calcination. Thus, spherical Mn₃O₄ particles, with uniform size and no agglomeration, could be prepared by precipitation conversion-roasting method.     

Synthesis and characterization studies of NiO nanorods for enhancing solar cell efficiency using photon upconversion materials

We report the effect of calcination on the structural and optical properties of nanocrystalline NiO nanoparticles were successfully synthesized by virtue of a single source precursor method at mild reaction conditions between nickel nitrate and sodium hydroxide. Composition, structure and morphology of the products were analyzed and characterized by X-ray powder diffraction (XRD). The ultra-violet visible (UV–vis) absorption peaks of NiO exhibited a large blue shift and the luminescent spectra had a strong and broad emission band centered at 328 nm. The intense band gap was also observed, with some spectral tuning, to give a range of absorption energies from 2.60 to 3.41 eV. The various functional groups present in the NiO nanorods were identified by FTIR analysis. High resolution transmission electron microscopy (HRTEM) and the chemical composition of the samples the valence states of elements were determined by X-ray photoelectron spectroscopy (XPS) in detail. The electrochemical response of NiO proved that the nano-nickel has a high level of functionality due to its small size and higher electrochemical activity without any modifications. The above studies demonstrate the potential for the utilization of NiO nanoparticles as a promising material for opto-electronics applications.     

Green nickel/nickel oxide nanoparticles for prospective antibacterial and environmental remediation applications

The extensive use of broad-spectrum antibiotics has resulted in antibiotic resistance for many human pathogenic bacteria making multi-drug resistance an increasing issue in the management of various infectious diseases. The current research focused on the green synthesis of nickel/nickel oxide nanoparticles (Ni^o/NiO nanoparticles) using seeds extract of Lactuca Serriola, bactericidal effect on human pathogenic bacteria and the photocatalytic activity. Highly crystalline nature of Ni^o/NiO nanoparticles was confirmed by X-ray diffraction (XRD). Infrared spectra of seeds extract of Lactuca Serriola (LS) evidenced the presence of many functional groups of phytochemicals acting as reducing or capping agents. From field emission scanning electron microscopic (FESEM) images of Ni^o/NiO nanoparticles, it was clearly observed that the particles were slightly spherical in shape with size <100 nm. The Ni^o/NiO nanoparticles were also tested against eight pathogenic bacteria (Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, Basilus subtilis, Basilus pumilus, Micrococcus luteus, E. coli and Bordetella bronchiseptica) which displayed significant antibacterial activity at low doses and almost complete inhibition at optimized concentration. From the bandgap study, the reduced bandgap energy value of 1.57 eV indicated its potential semiconductor photocatalytic behavior. Higher degradation efficiency against the model contaminant crystal violet dye, possibility of multiple degradation mechanisms and simple recovery suggested that the green synthesized Ni^o/NiO nanoparticles might be best suitable candidates for environmental remediation applications.     

氢氧焰燃烧制备纳米Al2O3颗粒及其分散性能

利用多重射流氢氧燃烧反应器,以AlCl3为前驱体制备了具有不同形貌和晶型结构的Al2O3纳米颗粒,表征了其形貌、晶型结构、比表面积、粒径分布等性能,考察了火焰燃烧形式和反应区最高温度等因素对颗粒性能的影响规律. 结果表明,随反应温度升高,Al2O3粒径不断长大,形貌从具有链状结构的不规则颗粒逐渐转变为分散性良好的球形颗粒;同时随反应温度升高和在高温火焰中停留时间延长,晶型由单纯g相逐渐转变为d和d*相. 产品纳米Al2O3颗粒具有较强亲水性,其分散液具有较好的稳定性. 探讨了高温快速反应过程中颗粒和团聚体的生长机理,最终产物的粒径和团聚体形貌取决于各主要影响条件的相互竞争.     

One Step Synthesis of NiO Nanoparticles via Solid-State Thermal Decomposition at Low-Temperature of Novel Aqua(2,9-dimethyl-1,10-phenanthroline)NiCl2 Complex

[NiCl₂(C₁₄H₁₂N₂)(H₂O)] complex has been synthesized from nickel chloride hexahydrate (NiCl₂·6H₂O) and 2,9-dimethyl-1,10-phenanthroline (dmphen) as N,N-bidentate ligand. The synthesized complex was characterized by elemental analysis, infrared (IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy and differential thermal/thermogravimetric analysis (TG/DTA). The complex was further confirmed by single crystal X-ray diffraction (XRD) as triclinic with space group P-1. The desired complex, subjected to thermal decomposition at low temperature of 400 ºC in an open atmosphere, revealed a novel and facile synthesis of pure NiO nanoparticles with uniform spherical particle; the structure of the NiO nanoparticles product was elucidated on the basis of Fourier transform infrared (FT-IR), UV-vis spectroscopy, TG/DTA, XRD, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDXS) and transmission electron microscopy (TEM).     

Structural evolution and stability studies of heterostructures comprised of carbon nanotubes decorated with nickel/nickel oxide core/shell nanoparticles

The single-step synthesis of heterostructures, denoted as CNC heterostructures, comprised of carbon nanotubes (CNTs) decorated with nickel (Ni)/nickel oxide (NiO) core/shell nanoparticles through a direct nucleation approach is reported. This approach allowed for a single-parameter and well-controlled structural evolution of Ni/NiO core/shell nanoparticles on CNTs. It was possible to control the size (∼12–52 nm), shape, spatial density, and chemical composition of nanoparticles formed on CNTs by changing the nanoparticle growth time (15 min to 15 h). It was observed that growth time of 15 h led to the reaction between phosphine-based stabilizers and Ni core forming solid and hollow Ni₁₂P₅ nanoparticles directly on CNTs. Thermal stability of CNC heterostructures (in N₂-rich atmosphere) dispersed on a silicon wafer as well as subsequent surface migration of nanoparticles were studied by annealing heterostructures at different temperatures (125–750 °C). In comparison to as-produced CNTs, the surface characteristics, oxidative resistance or thermal stability, and changes in heterostructure compositions were studied using electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The heterostructures showed greater oxidative resistance as compared to as-produced CNTs.     

Silica coated ferrite nanoparticles: Influence of citrate functionalization procedure on final particle morphology

In this paper, magnetic nanoparticles (Fe₃O₄ and NiFe₂O₄) were coated with a biocompatible silica shell via hydrolysis and condensation of tetraethyl orthosilicate (TEOS) by the Stöber process. Magnetic nanoparticles, prepared by chemical co-precipitation from iron and nickel salts, were functionalized with citric acid, in order to provide their deagglomeration and to enable their coating with silica. The parameters of the functionalization procedure were varied (concentration–pH and type of treatment), in order to examine if and how this particular step of preparation affects the final morphology of the core-shell particles. Transmission electron microscopy, zeta potential and particle size measurements revealed that the morphology and the size of obtained core shell particles depend significantly on the core particle size, and thus on the parameters of the functionalization step.     

Gas-sensing properties of multi-walled carbon-nanotube sheet coated with NiO

A binary, nanostructured carbon-nanotube (CNT) sheet coated with nickel oxide (NiO) acting as gas sensor was fabricated for the utilization as hydrogen (H₂) sensor. Thermal annealing was conducted to improve the sensing ability of the sensor at room temperature. In order to investigate the effect of the surface area of the sensing material, NiO particles of various sizes were deposited onto CNT sheets by electrodeposition, which is a simple method for binary composites. We found a much higher sensitivity at room temperature after thermal annealing. Moreover, the size of the NiO particles significantly affects the sensitivity of the sensor.