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。     

纳米氧化镍的制备及性能表征

以硫酸镍为原料,碳酸氢铵为沉淀剂,吐温-80作为添加剂,采用液相沉淀法,在水溶液中获得前体,然后经煅烧制备纳米氧化镍粉体。采用XRD和SEM对其结构和形貌进行表征,系统地研究了硫酸镍与碳酸氢铵的摩尔比、反应时间、热处理温度以及吐温-80用量对纳米氧化镍收率和粒径的影响。研究结果表明,在硫酸镍与碳酸氢铵的摩尔比1∶4、吐温-80与硫酸镍溶液体积比为1.25∶100、反应时间105min、热处理温度500℃和吐温-80用量为硫酸镍溶液体积的1.25%的条件下,可获得粒径为38～60nm的氧化镍,其收率可达79%。     

纳米氧化镍的合成研究

以硝酸镍为原料,加入柠檬酸、氨水、氢氧化钠和硫酸等添加物,通过溶剂-凝胶法以及固相法水热法合成纳米氧化镍.采用了X射线衍射仪(XRD)分析了产品结构,扫描电镜(SEM)分析了晶体形貌,粒度仪测量了纳米氧化镍的粒径.结果表明,随着温度的升高,颗粒结晶逐渐完善,产品粒径增大.固相法合成产物的粒径明显小于溶剂-凝胶法的产物....     

微波反应时间对纳米片状氧化镍 微球的形貌及电性能影响

以硝酸镍为镍源,采用微波辅助法导电基底Ni网上原位生长氧化镍微球,讨论了微波反应时间对纳米片状氧化镍微球结构和形貌的影响。采用X射线衍射（XRD）、扫描电镜（SEM）、透射电子显微镜（TEM）对其结构和形貌做了表征。结果表明,反应时间对产物结构和形貌具有较大的影响,当微波功率为100 W、反应时间为1.5 h时,电极的电流密度为1 A/g,电极的比容量达到350 F/g,并呈现出较好的倍率特性。     

热处理对微乳液法制备纳米氧化镍的影响

微乳液法是近年来制备纳米颗粒的有效方法之一，具有装置简单，操作容易，微粒可控等优点。以氯化镍和氨水为原料，以Triton X-100／环己彬正己醇／水为反相微乳体系，成功制备出纳米氧化镍前驱体，然后对前驱体进行热处理，得到纳米氧化镍粉末，系统考察了热处理对纳米氧化镍颗粒形貌、粒径分布的影响。结果显示，利用微乳液法制备的氧化镍纳米颗粒大小、形态及分散性优于经热处理后的粉末；X射线衍射谱及透射电镜显示，热处理后的氧化镍粉末粒径随着热处理温度的升高而增大。     

氧化镍纳米微球的水热法制备与电容性能研究

以硝酸镍为镍源、尿素为均相沉淀剂,在肉桂酸的协同作用下,采用水热法成功制得前驱体纳米微球,再经煅烧得到纳米微球状氧化镍。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)等手段对样品进行表征与分析。研究了前驱物浓度、温度和肉桂酸修饰剂加入量对纳米微球状氧化镍形貌的影响。结果表明,在电流密度为5 m A/cm~2时,比电容为323.6 F/g,具有良好的循环伏安性与循环稳定性。     

纳米氧化镍的低温固相合成及电容性能研究

通过低热固相反应法合成了纳米氧化镍,在不同温度热处理条件下研究氧化镍的结构、形貌及其作为超级电容器电极材料的电化学性能。采用XRD和SEM表征产物的结构特点,采用循环伏安和恒流充放电等方法表征其电化学性能。XRD测试结果表明,所制备的氧化镍为立方相,且随着热处理温度升高,晶型趋于完整。SEM和电化学测试结果表明,高温热处理（>400 ℃）使样品团聚更为严重,导致电极材料利用率降低,质子传递阻力加大,比电容急剧下降;低温处理颗粒分布均匀,粒子间存在孔道,使电极具有较大的比容量（228 F/g）和良好的化学稳定性,在20 mV/s快速扫描速率下,电极显示出良好的倍率特性。     

纳米氧化镍的乙烷氧化脱氢催化性能研究

采用溶胶-凝胶法制备了纳米氧化镍催化剂,其具有较好的低温催化乙烷氧化脱氢(ODHE)性能,通过SEM和XRD表征了该催化剂的形貌和结构,并研究了纳米NiO催化下ODHE反应的影响因素.     

燃烧-还原法制备镍纳米微粒

采用燃烧法制备纳米氧化镍前驱体．再用氢气还原。得到了镍纳米微粒。利用XRD、TEM对样品的成分、晶体结构和形貌进行了分析。结果表明．所制得的镍纳米颗粒纯度高。粒径分布为40～100nm。呈较规则的球形链状分布。最佳反应温度为300℃．反应时间为2h．制备氧化物前驱体时甘氨酸和硝酸根的最佳配比(GIy／NO3^-)为0．25。     

纳米氧化镍在铁镍蓄电池中的应用研究

采用均相沉淀法,以硝酸镍溶液和尿素溶液为原料,制备出纳米氧化镍;将纳米氧化镍取代传统的普通氧化镍和碳棒一起制成纳米氧化镍电极,应用于铁镍蓄电池中,研究了其电化学性能;比较了纳米氧化镍蓄电池和非纳米氧化镍蓄电池的充放电特性,发现前者的放电性能明显优于后者,其充电性能也表现出更好的态势。     

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.     

纳米多孔NiO类空心微球负极材料的制备与储锂性能

以NiCl₂·6H₂O、尿素、葡萄糖为原料采用水热法制备了NiO前体,将前体在空气中烧结最终得到NiO电极活性材料。该NiO样品具有镂空结构的类空心球形貌,且由50~100 nm初级纳米颗粒构成。对该NiO样品作为锂离子电池负极材料的储锂性能进行了研究,结果发现赝电容效应对该材料储锂容量和倍率性能有重要贡献。因独特的空心纳米结构和赝电容效应,该材料表现出出色的电化学循环稳定性和优异的大倍率充放电性能。在500 mA·g^-1电流密度下,100圈充放电循环后放电比容量为650 mA·h·g^-1,容量保持率达86.6%;在10 A·g^-1的超高倍率下,其稳定放电比容量仍高达432 mA·h·g^-1。     

Spherical NiO-C composite for anode material of lithium ion batteries

Spherical NiO-C composite was prepared by dispersing spherical NiO in glucose solution and subsequent carbonization under hydrothermal conditions at 180 °C. The microstructure and morphology of the NiO-C and NiO powders were characterized by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical properties of the electrodes were measured by galvanostatic charge-discharge tests, cyclic voltammetric analysis (CV), and electrochemical impedance spectroscopy (EIS). SEM images showed that the amorphous carbon not only coated on the surface but also filled the inner pores of the NiO spheres. Electrochemical tests showed that the NiO-C composite exhibited higher initial coulombic efficiency (66.6%) than NiO (56.4%), and better cycling performances. The improvement of these properties is attributed to the carbon, as it can reduce the specific surface area of porous sphere, and enhance the conductivity of porous NiO.     

水热法制备片状纳米氧化镍及其光催化性能

采用水热法制备片状纳米NiO,用XRD和TEM对样品的晶型及颗粒形貌进行了表征。以蒽醌染料KN-R为对象,紫外灯为光源,研究了催化剂热处理温度、催化剂用量、光照时间、染料的初始浓度等因素对染料脱色率的影响,以及催化剂的重复利用效果。结果表明：NiO催化剂能显著降解蒽醌染料KN-R,且能重复利用,在未曝气供氧时,NiO的催化活性优于p-25 TiO2。     

Eggplant as an appreciable bio-template for green synthesis of NiO nanoparticles: Study of physical and photocatalytic properties

In this study, we described a green, sustainable, and feasible method for synthesizing 5 nm NiO nanoparticles. Eggplant skin was chosen as an appropriate bio-template with a high potential to induce its structure into the desired metal oxide. Two approaches were used and compared to synthesize NiO bio-template: hydrothermal and sol-gel. The morphology and physical properties of the obtained NiO nanoparticles were evaluated using FESEM, TEM, XRD, BET, FT-IR, TGA, and UV–Vis analyses. All these methods confirm that the hydrothermal method is a better approach for synthesizing NiO bio-template nanoparticles than the sol-gel method. UV–Vis analysis revealed that the NiO nanoparticles produced by the hydrothermal method have a low bandgap of 2.88 eV, which is a key factor for photocatalytic applications.     

镂空结构氧化镍微球的制备及性质研究

通过水热合成法,以葡萄糖酸钠与硝酸镍为起始原料,一步法制备了前驱体碳杂Ni(OH)2复合微球(C-Ni(OH)2)。然后以制得的C-Ni(OH)2微球前驱体,在空气氛围下进行焙烧,制备出镂空结构NiO微球。通过场发射扫描电镜(FE-SEM)、X-射线衍射(XRD)、X-射线能谱(EDS)和氮气吸附脱附(EBT)等实验方法对其进行了分析,结果表明该微球主要是由几十个纳米的颗粒结合而成。由于前驱体为碳杂Ni(OH)2复合微球,氢氧化镍不仅存在于该微球的表面,而是存在于整个微球中,所以导致了部分焙烧出的NiO空心球出现了特殊的"球套球"的结构。     

基于片状前驱体组装中孔NiO微球

利用醇水混合溶剂作为反应介质,以硝酸镍(Ni(NO3)2.6H2O)为Ni源,尿素(CO(NH2)2)为沉淀剂,合成一种纳米片组装的碱式镍化合物微球,经热处理得到由NiO中孔纳米片组装的微球.采用X射线衍射仪、环境扫描电镜、傅立叶红外光谱仪和比表面及孔径分布测试仪对产物进行表征.结果表明:所得前驱体是一种片状结构的碱式碳酸镍盐(NiO2.45C0.74N0.25H2.90),经热处理后NiO纳米片单元上形成2.5和40 nm 2种孔径的中孔结构.改变尿素用量由0.01 mol增加至0.03 mol,会形成Ni(HCO3)2颗粒,从而改变微球表面形貌.结合PEG的模板作用和层状碱式金属盐类物质的成核及生长特性,提出了微米尺度球形组装NiO中孔纳米片的可能生长机理.     

Nanoscale morphology dependent pseudocapacitance of NiO: Influence of intercalating anions during synthesis

Three nano-porous NiO samples with high specific surface area were prepared by a simple hydrothermal method under homogeneous precipitation conditions using CTAB as a template and urea as the hydrolysis controlling agent. This study was done to determine the effect of different anions (acetate, nitrate and chloride) present in the precursor salts on the morphology and pseudocapacitance behavior of NiO. The samples were characterized by thermogravimetry (TG), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), Brunauer-Emmet-Teller (BET) isotherm and field emission scanning electron microscopy (FESEM). The final NiO samples showed different hierarchical surface morphologies and their effect on the electrochemical pseudocapacitance behavior was carefully studied by cyclic voltammetry, galvanostatic charge-discharge cycles (chronopotentiometry) and impedance spectroscopic techniques. The specific capacitance of NiO sample synthesized by NO3- ion intercalation showed higher surface area, intermediate porosity and a novel pine-cone morphology with nano-wire surface attachments. This sample exhibits the highest pseudocapacitance of 279 F g(-1) at a scan rate of 5 mV s(-1), calculated from the cyclic voltammetry measurements. The sample synthesized by Cl- intercalation shows a nano-flower morphology with lower surface area, porosity and pseudocapacitance behaviour. The NiO sample prepared in the presence of CH3COO- ions showed a honeycomb type surface morphology with an intermediate pseudocapacitance value but higher reversibility. The galvanostatic charge-discharge and impedance spectroscopic measurements on these NiO electrodes were consistent with CV results. The Coulombic efficiency of all the three NiO samples was found to be high (～85 to ～99%) after 100 galvanostatic charge-discharge cycles. This study shows that the surface morphology and porosity of NiO are strongly influenced by the anions in the precursor salts, and in turn affect significantly the pseudocapacitance behavior and the power performance of NiO powders.     

Highly dispersed NiW/γ-Al2O3 catalyst prepared by hydrothermal deposition method

This article describes a novel hydrothermal deposition method for preparing highly dispersed NiW/γ-Al₂O₃ catalysts and demonstrates its advantages over the conventional impregnation method. Via the hydrothermal precipitation reactions between sodium tungstate and hydrochloric acid and between nickel nitrate and urea, respectively, the active species W and Ni were deposited on γ-Al₂O₃. In the hydrothermal deposition of WO₃, a surfactant hexadecyltrimethyl ammonium bromide (CTAB) was used to prevent the aggregation of WO₃. The characterization results obtained by means of X-ray photoelectron spectroscopy (XPS), N₂ adsorption and high-resolution transmission electron microscopy (HRTEM) measurements showed that compared with the catalyst prepared by the conventional impregnation method, the catalyst with the same metal contents prepared by the hydrothermal deposition had much higher W and Ni dispersion, higher specific surface area, larger pore volume, the significantly decreased slab length and slightly increased stacking degree of sulfided W species, leading to the significantly enhanced dibenzothiophene (DBT) hydrodesulfurization (HDS) activity. The DBT HDS assessment results also revealed that the catalyst containing 17.7 wt% WO₃ and 2.4 wt% NiO prepared by the hydrothermal deposition method had the similar DBT HDS activity as a commercial NiW/γ-Al₂O₃ catalyst containing 23 wt% WO₃ and 2.6 wt% NiO, resulting in the greatly decreased amount of active metals for achieving the same HDS activity.     

Structural evolution of hierarchical porous NiO/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> composites and their application for removal of dyes by adsorption

Hierarchical porous NiO/Al₂O₃ composites were successfully prepared by two-steps. First, the core-shell structured Al₂O₃ microspheres were prepared via a template-free hydrothermal route using KAl(SO₄)₂·12H₂O and Al₂(SO₄)₃·18H₂O as aluminum source. Then, the NiO/Al₂O₃ composites with micro- and nano-hierarchical structures were prepared by a hydrothermal method combining the subsequent calcination process. The obtained characterization result presented that the morphology of hierarchical Al₂O₃ microsphere tuned to irregular platelets by simply varying Ni/Al ratios. The BET analysis showed that the special surface area from 52.12m² g^?1 to 214.8m² g^?1 after two hydrothermal complex process. Effects of Ni/Al ratio, adsorbent dosage, Congo red (CR) concentration, coexisting ions, adsorption time and temperature were investigated. The obtained results indicated that NiO/Al₂O₃ composite had the high adsorption efficiency (99.6%) and great adsorption capacity (186.9mg g^?1) under the optimum conditions. The adsorption isotherm and kinetics data were found to be well fitted and in good agreement with the Langmuir isotherm model and pseudo-second order model, respectively. The hierarchical porous NiO/Al₂O₃ composites presented remarkably higher adsorption efficiency during five recycling, which showed their potential as the highly efficient adsorbent for removal of CR in wastewater.