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.     

溶胶—凝胶法制备NiO／SiO2催化剂研究

分别以正硅酸乙酯、硝酸镍为硅源和镍源,采用溶胶－凝胶法,经超临界流体干燥和普通干燥制备了NiO-A-SiO2、NiO-G-SiO2催化剂;以气凝胶和干凝胶为载体,采用浸渍法制备了NiO/A-SiO2、NiO/G-SiO2催化剂。并用XRD、TEM、BET、TPR等手段,研究了制备方法对催化剂织构、结构和Ni物种存在形态的影响,发现NiO-A-SiO2和NiO-G-SiO2催化剂上高度分散的NiO簇团与SiO2之间有较强的相互作用,其顺酐液相选择加氢转化率低于10％;NiO/G-SiO2催化剂上,以单一物种形态存在的NiO与SiO2相互作用弱,顺酐转化率为42％;NiO/A-SiO2催化剂上,以多种形态存在的微量NiO与SiO2间的相互作用较复杂,其顺酐液相选择加氢的转化率和丁二酸酐的选择性分别可达100％和98％。     

镍盐和氧化镍在NaY沸石中存在状态研究

用ＸＲＤ、ＥＸＡＦＳ和ＴＰＲ方法研究了Ｎｉ（ＮＯ３）２／ＮａＹ和ＮｉＯ／ＮａＹ分散体系。在沸石上，Ｎｉ（ＮＯ３）２的分散比ＮｉＯ容易得多。ＸＲＤ相定量方法测定的ＮｉＯ在ＮａＹ沸石上的分散阈值很低，仅为密置单层容量的２％左右。在分散阈值关ＮｉＯ在沸石上处于分散相和笼外小晶粒两种状态。分散相ＮｉＯ比笼外ＮｉＯ小晶粒难还原。样品中ＮｉＯ含量超过阈值时，笼外小晶粒长大成ＸＲＤ可检测的较大晶粒。     

Photodegradation of orange II dye using p-n junction NiO/TiO2 composite,and assessment of its biological activities

The chemical reduction method was used to synthesize nickel oxide particles (NiO) and NiO supported on titanium dioxide (NiO/TiO₂ nanocomposite). The composites were characterized through scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The morphological investigation showed that pseudocubic NiO are present in dispersed as well as agglomerated forms. Whereas NiO particles (<200 nm) are evenly deposited over the surface of TiO₂ in NiO/TiO₂ composite. The formation of NiO and NiO/TiO₂ was also verified by XRD analysis. The synthesized NiO and NiO/TiO₂ were used as photocatalysts for the degradation of Orange II (OII) dye. According to the degradation investigation, both NiO and NiO/TiO₂ composite degraded OII dye more efficiently when exposed to UV light. The results indicated that NiO degraded 93% and NiO/TiO₂ composites degraded approximately 96% of OII dye within 30 min. Both photocatalysts are highly sustainable and have significant OII dye degradation recyclability. Moreover, NiO and NiO/TiO₂ exhibited promising bioactivities (antioxidant activity of 80%) against the pathogenic bacteria Citrobacter and Providencia, which is comparable with the standard ascorbic acid (88%).     

Fabrication of NiO coated SiO2 and SiO2 coated NiO for the removal of Pb2＋ ions

We have prepared silica,SiO2coated NiO and NiO coated SiO2by sol-gel method.The physicochemical properties of the desired materials were investigated by surface charge properties,scanning electron microscopy（SEM）,energy dispersive X-ray（EDX） spectroscopy,surface area measurements and X-ray diffraction（XRD） analyses.The point of zero charge（PZC） of the solid was determined by the salt addition method.In coated materials,two PZC values were noted representing the surface charge of their counterparts.The SEM image of SiO2coated NiO displays a uniform coating of silica on the surface of NiO whereas in case of NiO coated SiO2,a honeycomb like appearance was observed with highly porous structures.In the diffractograms of NiO,the characteristic peaks were suppressed in NiO coated silica however,no diffraction peak could be seen in SiO2coated NiO.Batch adsorption technique was applied for the removal of Pb2＋ions from aqueous solution.The sorption trend for Pb2＋ions was observed in the order of NiO coated SiO2〉 SiO2coated NiO 〉 NiO 〉 SiO2.This trend confirms that the coated materials have more sorption capacities than their parent counterparts.     

NiO晶粒尺寸对SOFC阳极电化学性能的影响

用溶胶凝胶法合成了具有高比表面积的纳米粒子NiO,用固相合成法制备了NiO-YSZ复合材料.阻抗谱测试表明,含纳米尺寸NiO的复合材料的极化电阻更小,电导率更高.以质量分数为55%的NiO-YSZ为阳极材料,并将其封接成单电池.结果表明,含纳米尺寸NiO的复合阳极制成的单电池,其输出功率更高,短路电流更大.通过减小NiO晶粒尺寸,可增大阳极三相反应界面长度,并获得性能优良的阳极材料.     

氧化镍/莫来石-刚玉催化剂中添加La2O3的作用

用ＸＲＤ，ＴＰＲ，ＴＧ－ＤＴＡ考察了氧化镍／莫来石－刚玉催化剂添加Ｌａ２Ｏ３对ＮｉＯ性质的影响及两者间的相互作用，Ｌａ２Ｏ３使得催化剂中ＮｉＯ的晶格常数及分散容量增大，而晶相含量减少，还发现，添加Ｌａ２Ｏ３，使一次ＴＰＲ过程中ＮｉＯ还原温度升高，耗氢量增加了Ｌａ２Ｏ３对二次ＴＰＲ中ＮｉＯ还原温度的影响减小，耗氢量不受影响，Ｌａ２Ｏ３的添加方式及含量不同，对ＮｉＯ性质的影响也不相同。     

Nickel foam-supported porous NiO/polyaniline film as anode for lithium ion batteries

Nickel foam-supported porous NiO film was prepared by a chemical bath deposition technique, and the NiO/polyaniline (PANI) film was obtained by depositing the PANI layer on the surface of the NiO film. The NiO film was constructed by NiO nanoflakes, and after the deposition of PANI, these nanoflakes were coated by PANI. As an anode for lithium ion batteries, the NiO/PANI film exhibits weaker polarization as compared to the NiO film. The specific capacity after 50 cycles for NiO/PANI film is 520 mAh g⁻¹ at 1 C, higher than that of NiO film (440 mAh g⁻¹). The improvement of these properties is attributed to the enhanced electrical conduction and film stability of the electrode with PANI.     

NiO增强Pt/C催化剂催化氧化甲醇活性的研究

本文基于NiO作为Pt催化甲醇助催化剂的思路,通过Pt纳米颗粒担载在NiO修饰的碳材料载体上制备了Pt/NiO-C催化剂,系统地研究了不同的NiO/C热处理温度对Pt粒径的影响,并重点探讨了Pt对NiO的质量比对催化氧化甲醇的影响。X射线衍射分析结果显示NiO和Pt均为立方晶系,且NiO的加入有利于主催化剂Pt形成较小的粒径,且经400℃热处理NiO修饰的C材料作为载体有利于Pt的有效分散。所获得的Pt/NiO-C催化剂的电化学活性在甲醇酸性溶液中通过循环伏安法(CV)和计时电流法(CA)进行性能测试。CV测试结果显示以Pt/NiO重量比为4∶1的催化剂其电氧化甲醇活性最大,其峰值氧化电流密度达806 mA/mgPt,是Pt/C催化剂的1.64倍。CA测试结果显示Pt/NiO-C比Pt/C具有更好的抗CO中毒性能和稳定性。     

Biosynthesis of Nickel oxide Nanoparticles from Euphorbia heterophylla (L.) and their biological application

Nickel oxide Nanoparticles (NiO NPs) were synthesized from E. heterophylla (L.) leaves extract act as reducing/capping agent by biosynthesis process. Further the synthesized NiO NPs was subjected for structural, optical and biological properties. The XRD pattern of NiO NPS exhibit face centred cubic (FCC) crystalline structure. The UV-DR spectrum of biosynthesized NiO NPs exhibited optical properties with well-defined at 321 nm and its exhibits optical band gap is 3.24 eV. The FT-IR spectrum of NiO NPs shows stretching vibration of Ni-O at 452 cm⁻¹. The morphological features of NiO NPs are rhombohedra and slightly agglomerated and then size of the biosynthesized NiO NPs as found in the range of 12–15 nm. The NiO NPs shows vital non-toxic properties on human erythrocytes and its interference in activity coagulation cascade both on PRP and PPP on human blood. The Bactericidal activity of NiO NPs was shows significant inhibitory activity against pathogenic bacterial strains. Further, NiO NPs show significant cytotoxicity against human lung cancer cell line (A549) and human hepatocarcinoma (HepG2) cell lines. Therefore, the study reveals states that, the E. heterophylla (L.) leaves extract is an effective reducing/capping agent for the formation of NiO NPs and its exhibits biological properties.     

氧化镍与载体相互作用对乙烷氧化脱氢的影响

研究了担载型催化剂NiO／γ－Al2O3的乙烷氧化脱氧（ODHE）性能,发现在400－500℃的考察温区内,担载型NiO较纯NiO的乙烯选择性有较大提高,保持在80％～90％之间,其中含17％Ni的样品500℃时乙烷的转化率为31％,乙烯选择性达82％．XRD、H2-TPR及原位磁测量结果表明：催化剂的活性相是与载体相互作用较小的、处于表层的微晶态NiO,NiO中非化学计量氧仍为活性氧物种．催化剂焙烧温度的提高,一方面降低了活性相中非化学计量氧量,同时加剧了NiO与载体γ－Al2O3的相互作用,二者均使活性降低．O2－TPD研究表明：与纯NiO相比,在Nio／γ－Al2O3中,其非化学计量氧的脱附温度发生变化,其中,α氧脱附温度向低温移动约50℃,而对乙烯选择性有关的β氧的脱出则向高温区移动了约200℃,正好与反应温区对应,进一步证实非化学计量氧与ODHE反应之间存在对应关系,上述结果表明那些对氧化镍还原有一定的阻碍作用,尤其阻碍镍深度还原（Ni2 →Nio）的载体对促进反应的乙烯选择性是有利的．     

用EXAFS方法研究双功能催化剂NiO-MoO3/γ-A2O3的表面分散那

The surface dispersion of bifunctional NiO-MoO_3/γ-alumina catalysts prepared by different procedures was studied with Ni-K EXAFS spectroscopy. The contents of NiO(13.6%) and MoO_3(16.5%) were the same in the three samples, which were a little higher than the monolayer dispersion capacity of each component on γ-Al_2O_3. The dispersion temperature was 450 ℃. The sample impregnated with NiO first shows that the NiO is monolayer-dispersed on γ-Al_2O_3 surface and the outer layer is MoO_3. The sample impregnated with MoO_3 and the outer layer is NiO. There is strong interaction between MoO_3 and γ-Al_2O_3 which affects the dispersion of NiO on the surface. The sample impregnated with NiO and MoO_3 simultaneously shows that the Ni is not dispersed in the form of NiO but another compound on the surface.     

Monolayer dispersion of NiO in NiO/Al2O3 catalysts probed by positronium atom

NiO/Al(2)O(3) catalysts with different NiO loadings were prepared by impregnation method. The monolayer dispersion capacity of NiO is determined to be about 9 wt.% through XRD quantitative phase analysis. Positron lifetime spectra measured for NiO/Al(2)O(3) catalysts comprise two long and two short lifetime components, where the long lifetimes τ(3) and τ(4) correspond to ortho-positronium (o-Ps) annihilation in microvoids and large pores, respectively. With increasing loading of NiO from 0 to 9 wt.%, τ(4) drops drastically from 88 to 38 ns. However, when the NiO loading is higher than 9 wt.%, τ(4) shows a slower decrease. Variation of λ(4) (1/τ(4)) as a function of the NiO content can be well fitted by two straight lines with different slopes. The relative intensity of τ(4) also shows a fast decrease followed by a slow decrease for the NiO content lower and higher than 9 wt.%, respectively. The coincidence Doppler broadening measurements reveal a continuous increase of S parameter with increasing NiO loading up to 9 wt.% and then a decrease afterwards. This is due to the variation in intensity of the narrow component contributed by the annihilation of para-positronium (p-Ps). Our results show that the annihilation behavior of positronium is very sensitive to the dispersion state of NiO on the surface of γ-Al(2)O(3). When the NiO loading is lower than monolayer dispersion capacity, spin conversion of positronium induced by NiO is the dominant effect, which causes decrease of the longest lifetime and its intensity but increase of the narrow component intensity. After the NiO loading is higher than monolayer dispersion capacity, the spin conversion effect becomes weaker and inhibition of positronium formation by NiO is strengthened, which results in decrease of both the long lifetime intensity and the narrow component intensity. The reaction rate constant is determined to be (1.50 ± 0.04) × 10(10) g mol(-1) s(-1) and (3.43 ± 0.20) × 10(9) g mol(-1) s(-1) for NiO content below and above monolayer dispersion capacity, respectively.     

Partial Oxidation of Butane to Syngas over Nickel Supported Catalysts Modified by Alkali Metal Oxide and Rare-Earth Metal Oxide

There are abundant supplies of mixture gases containing CH4, C2H6, C3H8 and C4H10, etc. from FCC (Fluidized Catalytic Cracking) tail gas, refinery gas, etc. Commonly, the mixture gases are primarily combusted to carbon dioxide because the complete separation of CH4, C2H6, C3H8 and C4H10, respectively, from the mixture gases may not be economical. Provided that syngas (CO+H2) could be produced from the mixture gases over nickel supported catalysts with high selectivity and conversion,…     

Graphene anchored with mesoporous NiO nanoplates as anode material for lithium-ion batteries

Graphene is an excellent substrate to load nanomaterials for energy applications due to its large surface area, excellent conductivity, mechanical strength, and chemical stability. In this study, thermal exfoliated functionalized graphene sheets with good conductivity and high BET surface area are anchored with mesoporous NiO nanoplates by in situ chemical synthesis approach. Electrochemical characterization shows that functionalized graphene sheets–NiO sample exhibits a high capacity of about 700 mAh/g at a discharge current density of 100 mA/g and a good cycling ability. The high capacity and good cycling ability of functionalized graphene sheets –NiO material were attributed to the intimate interaction between the graphene sheets and NiO nanoplates. The graphene sheets not only enhance the conductivity of NiO nanoplates but also improve the structure stability of NiO nanoplates. Furthermore, the mesoporous structure of NiO nanoplates is available to the transfer of electrolyte. Such functionalized graphene sheets–NiO nanocomposite could be a promising candidate material for a high-capacity, low cost, and nontoxic anode for lithium-ion batteries.     

LiFeO_2包覆MCFC氧化镍阴极的制备及性能研究

以硝酸锂和硝酸铁为原料 ,柠檬酸作燃料 ,采用燃烧合成法制备了铁酸锂包覆的多孔氧化镍阴极 .X_射线衍射技术 (XRD)、X_射线能量散射谱 (EDAX)和电子显微镜 (TEM和SEM )分析表明 ,在氧化镍颗粒表面的包覆层是由直径小于 10 0nm的铁酸锂微粒所构成 ,并与氧化镍颗粒紧密烧结在一起 ,有效地减少了氧化镍与熔融碳酸盐的接触面积 ,从而降低了氧化镍的溶解度 .同时 ,本文还研究了该阴极在熔融碳酸盐燃料电池中的电性能 ,并与未包覆的NiO阴极进行比较     

脉冲激光沉积纳米NiO薄膜

Na Cl型 Ni O是一种 p型半导体 ,广泛用于传感器、催化剂、涂料、磁性材料及电极材料等领域[1～ 5] .最近 ,Poizot等 [6] 又报道了 Ni O可作为锂离子电池的阳极材料 ,使 Ni O成为又一新的研究热点 .纳米 Ni O粉末的制备方法有多种 ,主要包括化学沉淀法和沉淀转换法 ,Ni O薄膜的制备主要采用磁控溅射、化学气相沉积和电沉积等方法 [7～ 12 ] .脉冲激光沉积法具有操作简单和成膜纯净等优点 ,因此是制备薄膜的重要方法之一 .本文采用脉冲激光沉积 (PLD)法在氧气氛中使用金属镍作为靶材料 ,不锈钢作为基片 ,对 Ni O薄膜的制备进行了研究…     

Adsorption of transition metal atoms on the NiO(100) surface and on NiO/Ag(100) thin films

We have studied the adsorption of Au, Pd, and Pt atoms on the NiO(100) surface and on NiO/Ag(100) thin films using plane wave DFT+U calculations. The scope of this work is to compare the adsorption properties of NiO, a reducible transition metal oxide, with those of MgO, a simple binary oxide with the same crystal structure and similar lattice parameter. At the same time, we are interested in the adsorption characteristics of NiO ultra-thin films (three atomic layers) deposited on Ag(100) single crystals. Also in this case the scope is to compare NiO/Ag(100) with the corresponding MgO/Ag(100) films which show unusual properties for the case of Au adsorption. The results show that the transition metal atoms bind in a similar way on NiO(100) and NiO/Ag(100) films, with Pt, Pd, and Au forming bonds of decreasing strength in this order. No charging effects occur for Au adsorbed on NiO/Ag(100) films, at variance with MgO/Ag(100). The reasons are analyzed in terms of work function of the metal/oxide interface. Possible ways to modify this property by growing alternate layers of MgO and NiO are discussed.     

Enhanced Electrocatalytic Hydrogen Oxidation on Ni/NiO/C Derived from a Nickel‐Based Metal–Organic Framework

The sluggish hydrogen oxidation reaction (HOR) under alkaline conditions has hindered the commercialization of hydroxide‐exchange membrane hydrogen fuel cells. A low‐cost Ni/NiO/C catalyst with abundant Ni/NiO interfacial sites was developed as a competent HOR electrocatalyst in alkaline media. Ni/NiO/C exhibits an HOR activity one order of magnitude higher than that of its parent Ni/C counterpart. Moreover, Ni/NiO/C also shows better stability and CO tolerance than commercial Pt/C in alkaline media, which renders it a very promising HOR electrocatalyst for hydrogen fuel cell applications. Density functional theory (DFT) calculations were also performed to shed light on the enhanced HOR performance of Ni/NiO/C; the DFT results indicate that both hydrogen and hydroxide achieve optimal binding energies at the Ni/NiO interface, resulting from the balanced electronic and oxophilic effects at the Ni/NiO interface.     

Adsorption of acid and basic dyes on NiO-SiO2 composites

A series of composites containing 2.5–21.0% NiO on a surface of macroporous silica is synthesized. The specific surface area of the composites measured by the thermal desorption of nitrogen decreases with an increase in the NiO content from 24 for the original silica carrier to 16 m²/g the for composite containing 21.0% NiO. The basic dye, methylene blue (MB), is only adsorbed on SiO₂ in water solutions, while acid blue anthraquinone (ABA) is only adsorbed on the NiO. The effective specific surface area Seff and effective diameters D _eff of NiO nanoparticles are calculated from the adsorption isotherms of ABA on NiO composites and on NiO synthesized without a carrier. S _eff of NiO nanoparticles decreases from 76 to 42 m²/g and D _eff increases from 8 to 14 nm with rising NiO content in the composites. The NiO nanoparticles synthesized without a carrier are characterized by the lowest S _eff (30 m²/g) and the largest D _eff (20 nm).