掺杂NiO的Ni(OH)_2电化学性能研究

于Ni(OH)2中添加具有电容特性和大电流充放电性能良好的NiO.研究发现掺杂5%NiO的Ni(OH)2在0.2C倍率下放电容量可达310.1mAh/g,而3C放电容量还可以保持79.5%.其循环伏安扫描氧化还原峰电位差仅为164mV,表明该材料的循环可逆性好.由此可见在Ni(OH)2掺杂适量的NiO,对于Ni(OH)2的大电流充放电性能确有改进作用.     

阴离子对鼠尾草提取物中Ni盐前体绿色合成的NiO纳米粒子磁性和结构性能的影响

采用绿色合成方法,将鼠尾草提取物用作还原和封端剂合成氧化镍纳米颗粒(NiO NPs)。此外,使用各种前驱体合成了NiO NPs,并使用扫描电子显微镜对其形貌进行了分析。利用傅里叶变换红外光谱和粉末X射线衍射(PXRD)对NiO NPs的结构进行了表征,使用振动样品磁强计测量了它们的磁性。PXRD研究表明,所有合成的NiO NPs都表现出具有高结晶度的面心立方相,并且形成了具有高纯度相的NiO。磁化研究结果表明,3种镍盐(乙酸盐、氯化物和硫酸盐)前驱体合成的NiO NPs分别表现出超顺磁、软铁磁和顺磁行为。     

A green biosynthesis of NiO nanoparticles using aqueous extract of Tamarix serotina and their characterization and application

Nickel oxide nanoparticles were prepared using nickel nitrate as precursor with extract of Tamarix serotina flowers and were characterized using powder X‐ray diffraction, infrared and UV spectroscopies, transmission electron microscopy, vibrating sample magnetometry and BET surface area measurements. Also, the nickel oxide nanoparticles were used as a green and recyclable nanocatalyst for the synthesis of quinoline derivatives. The products are obtained in good to high yields (60–90%) from a one‐pot reaction of 2‐aminobenzophenone and various carbonyl compounds. Copyright © 2016 John Wiley & Sons, Ltd.     

NiO的单层分散态及其载体效应

The NiO dispersion phase on three different supports have been studied by EXAFS in combination with XRD quantitative phase analysis. The result of XRD shows the threshold of NiO/γ-Al_2O_3 system is larger than that of NiO/TiO_2 system and the threshold of NiO/SiO_2 system is the least. From the FT functions of EXAFS for samples we can find that in NiO/γ-Al_2O_3 system a part of Ni changes its coordination polyhedra into tetrahedra, the Ni-Ni coordination peaks reduce markedly with the decrease of NiO content in samples. The result of EXAFS fitting and phase isolation shows Ni-Ni coordination number increases with the increase of NiO content in samples of NiO/γ-Al_2O_3 system and reaches a maximum value of 4.0 and remains constant when NiO content reaches the threshold obtained by XRD. It shows the structure of NiO dispersion phase is in better agreement with the NiO monolayer dispersion model than any other models.
In FT functions of EXAFS for samples at thresholds of two systems the Ni-Ni coordination peaks of NiO/TiO_2 system is much lower than those of NiO/γ-Al_2O_3 system. But they are similar when their NiO contents both close to the threshold of NiO/TiO_2 system. It shows that though the dispersion capacity of NiO in NiO/TiO_2 system is less than that in NiO/γ-Al_2O_3 system its dispersion performance is better.
In NiO/SiO_2 system the coordination peaks are similar to those of pure NiO and the Ni-Ni coordination number approaches 12 of the pure NiO. It shows it is difficult for NiO to disperse on the surface of SiO_2. In fact, for the NiO/SiO_2 system the threshold obtained by XRD is beyond the experiment accuracy so there is no threshold for this system.
Therefore above facts indicate that dispersion threshold and reducing of metal-metal coordination number of the dispersion phase is a quite characteristic feature of monolayer dispersion state.     

纳米氧化镍微粉的制备及光吸收谱

Uniform nanosized NiO particles were prepared by a chemical coprecipitation using NiCl2?6H2O as the starting material. The relationship between various annealing temperatures and grain size of NiO crystallite was investigated. Optical reflectivity spectra of Nanometer-sized NiO powders at room temperature were studied. The results show that seven optical absorption bands (P1、 P2、P3、P4、P5、P6 and P7) with the peak energies of 3.30, 2.99, 2.78, 2.25,1.92, 1.72 and 1.07eV, respectively, are located on a continuous refiectivity background. P1、 P2、P3 and P4 exhibit "blue shift", but P5、P6 and P7 present "red shift" in comparison with that of single crystal NiO. The continuous reflectivity background increases rapidly with increasing the annealing temperature from 500℃ to 600℃ to 700℃. The origins of P1 to P7 and the reasons of "blue shift", "red shift" and the increase of the reflectivity background with increasing the annealing temperature have been analyzed in detail.     

Thermal solid–solid interactions and physicochemical properties of NiO/Fe2O3 system doped with K2O

The effects of calcination temperature and doping with K₂O on solid–solid interactions and physicochemical properties of NiO/Fe₂O₃ system were investigated using TG, DTA and XRD techniques. The amounts of potassium, expressed as mol% K₂O were 0.62, 1.23, 2.44 and 4.26. The pure and variously doped mixed solids were thermally treated at 300, 500, 750, 900 and 1000 °C. The catalytic activity was determined for each solid in H₂O₂ decomposition reaction at 30–50 °C. The results obtained showed that the doping process much affected the degree of crystallinity of both NiO and Fe₂O₃ phases detected for all solids calcined at 300 and 500 °C. Fe₂O₃ interacted readily with NiO at temperature starting from 700 °C producing crystalline NiFe₂O₄ phase. The degree of reaction propagation increased with increasing calcination temperature. The completion of this reaction required a prolonged heating at temperature >900 °C. K₂O-doping stimulates the ferrite formation to an extent proportional to its amount added. The stimulation effect of potassium was evidenced by following up the change in the peak height of certain diffraction lines characteristic NiO, Fe₂O₃, NiFe₂O₄ phases located at “d” spacing 2.08, 2.69 and 2.95 Å, respectively. The change of peak height of the diffraction lines at 2.95 Å as a function of firing temperature of pure and doped mixed solids enabled the calculation of the activation energy (ΔE) of the ferrite formation. The computed ΔE values were 120, 80, 49, 36 and 25 kJ mol⁻¹ for pure and variously doped solids, respectively. The decrease in ΔE value of NiFe₂O₄ formation as a function of dopant added was not only attributed to an effective increase in the mobility of reacting cations but also to the formation of potassium ferrite. The calcination temperature and doping with K₂O much affected the catalytic activity of the system under investigation.     

Effect of heat treatment on pore structure in nano-crystalline NiO: A small angle neutron scattering study

Nano-crystalline nickel oxide powder was synthesized by a precipitation route. Powder samples were heat treated at 300, 600 and 900 °C, and pore structure evolution was followed by small angle neutron scattering (SANS) technique. SANS measurements were carried out also on pelleted samples in order to study the modifications of pore morphology due to heat treatment. SANS data reveal scattering from pores at two different length scales. The pore structure at various heat treatment temperatures does not follow any scaling behavior.     

Structural,morphological, optical and third order nonlinear optical response of spin-coated NiO thin films: An effect of N doping

The present work deals with the deposition of NiO and Nitrogen (N)-doped NiO thin films by sol-gel spin coating technique. Structural, morphological, linear and non-linear optical characteristics of undoped and N-doped (1–15 wt%) NiO films were studied. From XRD measurements, it is evident that single phase nano crystalline NiO is formed for all doping concentrations. Surface morphology study shows that higher concentration of N doped NiO thin films were of high quality and EDX mapping confirmed the doping of Nitrogen in films. The Raman spectra of the studied films were analyzed over the range of 1400-200 cm⁻¹. The optical studies confirm that as doping increases, transparency of the film decreases (except at 10% N doping) and the band gap narrows. Nonlinear parameters such as refractive index and susceptibilities also depend on N dopant concentration. Z-scan studies viz., absorption index, nonlinear refractive index were carried out on undoped and N doped NiO samples and the results were matched with theoretical calculated values.     

Fabrication of NiO photoelectrodes by aerosol‐assisted chemical vapour deposition (AACVD)

Nanostructured nickel oxide (NiO) photoelectrodes were fabricated with controlled morphology and texture using single‐step aerosol‐assisted chemical vapour deposition (AACVD). The durable one‐step film fabrication process resulted in highly crystalline columnar structure. Texture controlled films were also fabricated from granular to crystalline columnar morphology by controlling the deposition temperature. The thin film electrodes are highly reproducible and possess an optical bandgap of ～3.7 eV and exhibit cathodic photocurrent. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)