SYNTHESIS OF NiO NANOPARTICLES IN ETHYLENE GLYCOL

NiO nanoparticles with well-dispersed property were prepared via a wet chemical method in ethylene glycol (EG) without soluble polymer as a protective agent. The mechanism of chemical process was proposed based on color change during the experiment. The dispersion function of EG was discussed.     

Electrospinning fabrication of rime-like NiO nanowires/nanofibers hierarchical architectures and their photocatalytic properties

Rime-like NiO Nanowires/nanofibers hierarchical architectures have been fabricated employing a co-precipitation reaction and electrospinning method. The synthesized hierarchical structure was characterized using SEM, XRD and BET analysis methods. The effects of growth temperature and reaction time on the morphologies of the as-prepared structures were investigated by SEM characterization and a possible mechanism for the formation of NiO hierarchical structures is proposed. Based on the nitrogen adsorption and desorption measurements, the BET surface area of the as-obtained sample is 61.0 m²/g and the pore sizes of ca. 5.0 nm. The catalytic efficiency of the NiO nanomaterials developed was evaluated by the photocatalytic degradation of acetaldehyde. In comparison with sphere-like and fiber-like structures, the NiO hierarchical structures show an excellent ability to rapidly acetaldehyde pollutant, which may be attributed to its unique hierarchical and porous surface structures.     

Self-Assembled Two-Dimensional NiO/CeO2 Heterostructure Rich in Oxygen Vacancies as Efficient Bifunctional Electrocatalyst for Alkaline Hydrogen Evolution and Oxygen Evolution

The development of high-efficiency bifunctional electrocatalysts toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline surroundings is essential and challenging for the large-scale generation of clean hydrogen. Herein, a novel self-assembled two-dimensional (2 D) NiO/CeO₂ heterostructure (HS) consisting of NiO and CeO₂ nanocrystals is prepared through a facile two-step approach, and utilized as an enhanced bifunctional electrocatalyst for the HER and OER under alkaline conditions. It is concluded that this 2 D NiO/CeO₂ HS, rich in oxygen vacancies, demonstrates attractive electrocatalytic properties for both the HER and OER in 1 m KOH, including low onset overpotential (η₁), η₁₀ and Tafel slope, excellent durability, as well as large active surface area. Therefore, the self-assembled 2 D NiO/CeO₂ HS is believed to be an efficient bifunctional electrocatalyst toward the HER and OER.     

NiO-SiO2 Sol-Gel Nanocomposite Films for Optical Gas Sensor

Recently nanocomposites with sensoring function are becoming a new area of interest in the field of optical gas sensor. In fact, the optical transmittance of nano-particles or thin films has been reported to be changed by atmosphere gases. In particular it was found that NiO, Co₃O₄ and Mn₃O₄ thin films showed reversible decrease in the Vis-NIR absorption due to CO.Aim of this work is the synthesis and the characterization of SiO₂ sol-gel glass films doped with NiO nanocrystals.Films of composition (100 – X)SiO₂-XNiO with X = 10, 20, 40, were obtained by mixing a matrix solution of Si(OC₂H₅)₄ (TEOS) and CH₃Si(OC₂H₅)₃ (MTES) as SiO₂ precursors, with a doping solution containing NiCl₂ as precursor for NiO particles.3-Aminopropyltriethoxysilane (3-APTES), bearing either an ammine group capable of coordinating the Ni ions and hydrolysable siloxane groups for anchoring the metal complex moiety to the silicate matrix, was used as bifunctional ligand.Transmission electron microscopy micrographs showed a uniform distribution of round shaped nanoparticles in film heated at 500°C with a mean diameter of 2.5 nm.The film composition evaluated from Rutherford backscattering spectrometry was in good agreement with the nominal one. As expected the density of the films heated at 1000°C is much higher than the density of the film heated at 500°C due to a residual porosity. Fourier transform infrared spectra also confirmed the presence of residual porosity in the films heated at 500°C.     

Synthesis and characterization of mesoporous nickel oxide for electrochemical capacitor

A mesoporous electrochemical active material NiO with face center cubic structure has been synthesized using supramolecular as template and urea as hydrolysis-controlling agent. The synthesized product was characterized physically by thermogravimetric analysis, X-ray diffraction, transmission electron microscopy, and Brunauer–Emmett–Teller-specific surface area measurement. Electrochemical characterization was performed using cyclic voltammetry and chronopotentiometry in 6 mol/l KOH aqueous solution electrolyte. A specific capacitance of approximately 327 F/g was obtained by annealing the sample at 350 °C. To get a better understanding of the effect of supramolecular template on improving the structure property and electrochemical performance, a compared experiment was also carried out in this work.     

Sol–gel derived nanostructured nickel oxide films: Effect of solvent on crystallographic orientations

Nickel oxide films were deposited onto glass substrates by sol–gel dip coating method using solvents of different polarities without any catalysts, templates or surfactants. Methanol, 1,4-butanediol, ethanol, and 2-propanol were used as solvents. The structural, optical and electrical properties of NiO films were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible spectroscopy and Hall effect measurements, respectively. Nickel oxide thin films with cubic phase crystal structure of various preferred orientations were obtained in the different solvents. The XRD results showed that films deposited from solution using higher polar solvents develop a (1 1 1) preferred orientation, while the (2 0 0)-orientated films were obtained using lower polar solvents. The average particle size increases with viscosity of solvents. Surface morphology of the nickel oxide film consisted of nanoparticles with uniform coverage of the substrate surface. The solvent of higher viscosity induced larger particle size. Band gap narrowing from 4.42 to 3.87 eV was observed using different solvents. The lower resistivity and Hall coefficient was obtained for prepared NiO films using higher polar solvents. The relationships between solvent physicochemical properties, preferred orientation, structural, optical and electrical properties of NiO films were investigated.     

Synthesis of Porous NiO Nanorods as High‐Performance Anode Materials for Lithium‐Ion Batteries

1D nanostructured metal oxides with porous structure have drawn wide attention to being used as high‐performance anode materials for lithium‐ion batteries (LIBs). This study puts forward a simple and scalable strategy to synthesize porous NiO nanorods with the help of a thermal treatment of metal‐organic frameworks in air. The NiO nanorods with an average diameter of approximately 38 nm are composed of nanosized primary particles. When evaluated as anode materials for LIBs, an initial discharge capacity of 743 mA h g^?1 is obtained at a current density of 100 mA g^?1, and a high reversible capacity is still maintained as high as 700 mA h g^?1 even after 60 charge–discharge cycles. The excellent electrochemical performance is mainly ascribed to the 1D porous structure.     

有序介孔C/NiO复合材料的合成及其电化学性能

以嵌段共聚物F127(Mw=12600, PEO106PPO70PEO106)为模板剂, Ni(Ac)2·4H2O为Ni源, 低分子量的酚醛树酯为碳源, 通过溶胶-凝胶三元共组装方法合成高度有序介孔C/NiO复合材料. 对样品进行X射线衍射(XRD)、透射电子显微镜(TEM)、N2吸脱附等结构表征及循环伏安(CV)等电化学性能测试. 结果显示, NiO晶体和碳组成了C/NiO复合材料的基本骨架, 该复合材料具有高度有序的介孔结构. NiO晶体的存在极大地提高了复合材料的电化学性能, 当C/NiO达到4:1(苯酚与Ni(Ac)2·4H2O的摩尔比)时复合材料的比电容达到444.1 F·g-1, 而有序的介孔结构并没有被破坏, 使得该材料具有较好的应用前景.     

Fabrication of biaxial textured NiO on Ni in a one-step process

A novel method for the preparation of biaxial textured nickel oxide on commercially available nickel via a modified surface oxidation epitaxy (SOE) process has been developed. Following studies of different heat-treatment procedures for both texturing of nickel and for the fabrication of nickel oxide the following method was found to yield the best results. Nickel was first textured under an argon — hydrogen atmosphere at 1000°C for 120 min, then the temperature was lowered to 800°C and the atmosphere was changed to argon with 3 ppm oxygen. Smooth and crack free c-axis textured and a–b aligned NiO buffer layers with an out-of-plane texture of 7.8° and an in-plane texture of 9.4° were successfully produced. Higher oxygen partial pressure and temperatures resulted in increased surface roughness and excessive grain growth.