纳米铁磁性合金包裹氧化铝复合微球的制备

用非均相沉淀法制备了CoFe,CoNi,CoFeNi包裹氧化铝3种微球前驱体,在还原气氛中于720 ℃焙烧2 h获得了包裹层颗粒分布均匀的纳米多元铁磁性合金/氧化铝复合微球.利用红外光谱、扫描电镜、能量散射光谱仪、X射线衍射仪对前驱体及热还原产物的成分、结构及形貌进行了表征,还分析研究了前驱体热分解过程.结果表明:包裹层CoFe,CoFeNi合金粒子的平均粒径为70～80 nm,CoNi合金粒子小于50 nm.前驱体的包裹层分别为无定型Fe2O3·nH2O,NiCO3·2Ni(OH)2·2H2O,Co2(OH)2CO3的混合物,热处理后这些无定型结构分别转变成了CoFe,CoNi和CoFeNi固溶体合金.     

熔盐辅助固相反应合成NiO纳米片

通过聚乙二醇表面活性剂辅助低热固相反应首先制备了薄片状Ni(OH)2前驱体,再将所得前驱体置于马弗炉中于KNO3熔盐存在的条件下,600℃热分解5 h得到NiO纳米片。进一步借助X-射线衍射测试和透射电镜测试对所制备的纳米材料的晶型和形貌大小进行了表征。X-射线衍射测试结果证实了所得样品分别为单一的立方相NiO。透射电镜测试结果表明,所得NiO为片状结构,且大部分呈不规则六边形结构,相邻两边夹角约为120°。NiO纳米片的平均粒径约60 nm。     

聚丙烯原位碳化合成石墨烯负载碳球纳米杂化材料研究

本研究以氧化石墨烯(GO)为模板负载氢氧化镍(Ni(OH)_2)和氢氧化钴(Co(OH)_2)纳米粒子,并分别熔融共混到聚丙烯(PP)中,利用PP原位碳化方法成功制备出GO负载碳球纳米杂化材料。利用X射线衍射(XRD)和拉曼波谱分析(Raman)对合成的Ni(OH)_2、Co(OH)_2、GO负载Ni(OH)_2和GO负载Co(OH)_2进行表征。采用透射电子显微镜(TEM)、XRD和Raman等对合成的石墨烯负载碳球纳米杂化材料的形貌结构和物理性质进行表征。结果表明:利用PP原位碳化可成功制备两种不同类型的石墨烯负载碳球纳米杂化材料。     

花状氢氧化镍的水热合成工艺研究

利用水热合成法制备了Ni(OH)_2粉体,采用电子扫描显微镜(SEM)、激光粒度仪、X-射线衍射仪(XRD)分析了Ni(OH)_2粉体的形貌、粒度及结构。结果表明:反应温度为120℃时,制备出来Ni(OH)_2粉体为β型Ni(OH)_2,形貌为花状微球结构,粒度曲线呈较好正态分布,颗粒大小均匀,峰值粒径约为45μm左右。     

NiO纳米晶的机械化学合成及其电化学性能

以NaCl为稀释剂,NaOH,NiCl2.6H2O为原料,采用固相机械化学反应制备Ni(OH)2前驱体。前驱体经焙烧可制得呈面心立方晶型的黑色NiO纳米晶粉末。用差热/热重分析前驱体的热处理过程,X射线衍射表征样品的结构,透射电镜(transmission electron microscope,TEM)观察粉末的形貌特征。TEM观察表明:产物为立方形颗粒,颗粒平均尺寸在80 nm左右,呈现良好的单分散性。用循环伏安法测试NiO的电化学性能,并计算其比电容值,考察前驱体焙烧温度对所得NiO电极的电化学性能的影响。研究发现:400℃处理所得NiO纳米材料在同一扫描速率下的充放电电流最大,比电容值最大,当扫描速度为1 mV/s时其比电容值可达209.32 F/g。     

LiFePO4/Ni复合微球的制备

通过控制反应沉淀-焙烧法首先制备了球形LiFePO4粉体,然后在LiFePO4粒子表面包覆柠檬酸镍凝胶,经还原热处理制得LiFePO4/Ni复合微球材料,并采用热重-差热分析、扫描电子显微镜、能谱分析、X射线衍射等手段研究了前驱体和焙烧产物的成分、微观结构、形貌及其热分解过程.结果表明;实验制备的LiFePO4/Ni复合材料由LiFePO4和金属Ni两相组成,保持了球形形貌和多孔结构,金属镍均匀分布于LiFePO4微球表面.     

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.     

镍盐的焙烧温度对Ni-Cu/ZrO_2-CeO_2-Al_2O_3催化剂在甲烷自热重整制氢中的影响

以Na2CO3为沉淀剂,在pH为9的沉淀条件下,采用并流沉淀法制备催化剂载体,考察了催化剂的活性组分前驱体Ni(NO3)2的焙烧温度(550、650和750℃)对Ni-Cu/ZrO2-CeO2-Al2O3在甲烷自热重整制氢反应的影响,并采用SEM方法表征了催化剂的表面结构。结果表明,Ni(NO3)2的焙烧温度对Ni-Cu/ZrO2-CeO2-Al2O3催化剂上的NiO颗粒分散性及催化剂的低温活性有很大的影响,650℃焙烧生成的催化剂上的NiO颗粒较小,分布均匀,分散性好,在反应温度650～850℃内,该催化剂的活性明显高于焙烧温度为550℃和750℃制备的催化剂。     

磁性介孔碳微球的制备及其对红霉素的吸附性能研究

构建了一种在磁性纳米颗粒表面包覆介孔碳层的制备方法。探究了2种硅前驱体四乙氧基硅烷(TEOS)和四丙氧基硅烷(TPOS)造孔剂对碳层表面孔结构的影响,同时研究了在碳微球制备过程中硅前驱体引入方式对碳层孔结构形成的影响。利用X射线衍射仪、透射电子显微镜、全孔分析等手段对材料的组成、形貌、比表面和孔结构进行表征。结果表明,采用TEOS和TPOS造孔剂,碳微球的比表面积较硅前驱体引入前有显著提高,在选定实验条件下比表面积可提高1. 5倍;同时丰富了介孔结构,介孔孔容占比由引入前的18%提高至90%以上。考察了该材料对抗生素红霉素的吸附性能,硅前驱体引入后的磁性介孔碳微球的吸附量提高3. 1～5. 5倍。     

绒球状氢氧化镍的合成及光催化性能

利用水热合成法合成了氢氧化镍粉体,采用电子扫描显微镜(SEM)、红外光谱仪(FTIR)分析了Ni(OH)2粉体的形貌及结构。并以氢氧化镍作为前驱体,加热分解制备氧化镍粉体,以亚甲基蓝为研究对象,紫外灯为光源,研究了氧化镍的光催化活性。结果表明:反应温度为120℃时,制备出来Ni(OH)2粉体为β型Ni(OH)2,形貌为花状微球结构,当Ni2+浓度为0.8 mol/L,尿素2 mol/L,反应温度为120℃,反应时间为12 h,Ni O对染料的降解率最高,可达89.5%。     

纳米氧化亚镍包覆Al复合粒子的制备

为了获得具有良好红外吸收特性及低发射率复合颜料,通过将纳米NiO复合于片状金属铝粉表面的方法,获得了复合效果好的纳米NiO/Al复合粒子.为了保证复合物的红外伪装性能,通过对复合前驱体Ni₂CO₃(OH)₂/Al的热分析,确定了对复合物的热处理温度.通过对复合物热处理前后的电镜照片分析,发现热处理前复合物表面是由线状的Ni₂CO₃(OH)₂交织而成的,而热处理后则变成了由纳米球状NiO粒子连接而成的球链.这种现象在同类研究中尚未见报道.对比所制备的纳米NiO/Al和NiO的XRD图谱,发现纳米NiO/Al中的NiO衍射峰宽化,表现出纳米粒子的特征,由半高宽计算出其晶粒粒径为12 nm.     

纳米氧化镍的制备及表征

以尿素、NiCl2·6H2O为原料,采用均相沉淀法制备了前驱体Ni(OH)2,再经高温煅烧,得到纳米氧化镍。用TG DTA热分析、X射线衍射(XRD)、扫描电镜观察(SEM)等测量方法对氧化镍前驱体的热分解过程、纳米氧化镍颗粒的晶体结构、粒径和形态进行了研究。     

松香基表面活性剂调控制备NiO纳米微球及其吸附刚果红

通过天然产物松香制备松香基表面活性剂，利用该表面活性剂调控晶体生长制备出多级Ni(OH)₂纳米结构，并进一步制备成NiO微球。通过FT-IR、NMR、XRD、SEM、TEM等表征确定了NiO的形貌及结构，通过BET等表征测试确定了其为多级多孔的结构。FT-IR、UV研究表明该多级纳米NiO对刚果红具有极高的吸附能力，其最大吸附量为657.89 mg/g，远优于商业NiO(337.18 mg/g)。研究结果表明：在pH值3，质量浓度为50 mg/L刚果红20 mL，吸附剂NiO适宜质量为16.8 mg时，吸附10 min达到平衡，平衡吸附量为50 mg/g。NiO对刚果红的吸附更符合Freundlich模型，吸附容易进行，吸附是吸热过程；吸附动力学符合准二级动力学方程，吸附过程以化学吸附为主。循环5次使用后吸附效率没有明显减弱，对刚果红去除率保持98%。     

PEG-directed microwave-assisted hydrothermal synthesis of spherical α-Ni(OH)2 and NiO architectures

Spherical α-Ni(OH)₂ architectures were synthesized by the microwave-assisted hydrothermal technique using PEG-6000 as the surfactant. NiO architectures with similar morphology were obtained by a simple thermal decomposition process of the precursor α-Ni(OH)₂ at 400 °C for 2 h and were confirmed by the X-ray diffraction (XRD) analysis. Scanning electron microscopy (SEM) revealed that the synthesized spherical α-Ni(OH)₂ and NiO architectures were composed of stacked lamellar sheets and transmission electron microscopy (TEM) showed that the α-Ni(OH)₂ and NiO architectures were polycrystalline. The effect of the PEG-6000 concentration on particle size was investigated and it was found that the average particle size of α-Ni(OH)₂ architectures decreased from 4.689 μm at C_PEG=2 mmol L⁻¹ to 3.907 μm at C_PEG=4 mmol L⁻¹, and the corresponding average particle size of NiO decreased from 2.818 μm to 2.492 μm. The optical absorption band gap of NiO architectures was determined to be about 2.7–3.0 eV by UV–vis spectroscopy.     

碳毡基体上电沉积Ni-Mo合金及其催化析氢性能

以碳毡为基体,采用瓦特型镀镍工艺电沉积镍,获得碳镍（C-Ni）电极,然后在离子液体体系中以C-Ni为基体电沉积Ni-Mo合金。采用扫描电镜和X射线衍射仪对合金电极的表面形貌和结构进行了表征,通过阴极极化曲线、交流阻抗等电化学测试研究了其析氢催化性能。实验结果表明,制得的Ni-Mo合金中Mo的质量百分含量约为5.12%,平均晶粒尺寸约为2.2 nm,为纳米晶结构;极化曲线测试表明,当电流密度为0.1 A·cm^-2时,Ni-Mo/C-Ni合金电极催化析氢电位较C-Ni电极正移108 mV,较碳毡正移557 mV,较水溶液中沉积的紫铜基Ni-Mo合金电极正移约50 mV;连续电解和断电流实验结果表明Ni-Mo/C-Ni合金电极具有良好的电化学稳定性,实用前景广阔。     

碳纤维表面化学涂覆NiO

采用均相沉淀法在碳纤维表面进行了NiO涂覆,研究了沉淀剂种类、脱水方式、沉淀剂浓度、沉淀剂添加速度和沉积反应时间对涂覆效果的影响. 采用SEM和XRD对涂层进行了表征,得到了制备NiO涂层较为合适的工艺条件为：以尿素为沉淀剂,采取缓慢升温的方式脱水,沉淀剂浓度0.20 mol/L,沉淀剂滴加速度2 mL/min,反应时间120 min. 在此条件下制备的NiO涂层厚度均匀,无脱落现象. 抗氧化性测试结果表明,涂覆NiO涂层后,碳纤维的抗氧化性有明显的提高.     

A comparison of mechanochemical methods for the synthesis of nanoparticulate nickel oxide

In this study, mechanochemical processing has been investigated as a means of manufacturing nanoparticulate powders of NiO. Two different reactant mixtures were examined and compared. The first system was based on mechanical milling of Ni(OH)₂ with NaCl diluent. Milling of this reactant mixture resulted in disintegration of the Ni(OH)₂ precursor and its progressive dispersal into the NaCl matrix. Subsequent heat treatment and washing yielded a nanocrystalline powder of NiO, which contained a significant proportion of particles with an unusual platelike morphology. The second system that was examined was based on mechanically activated reaction of NiCl₂ + Na₂CO₃ + 4NaCl. Milling resulted in mixing and microstructural refinement of the reactant mixture. Chemical reaction during post-milling heat treatment resulted in the formation of a powder consisting of nanocrystalline NiO grains embedded in NaCl. Removal of the NaCl by washing with water yielded NiO nanoparticles with an equiaxed particle shape.     

Nanoscale resistive switching memory device composed of NiO nanodot and graphene nanoribbon nanogap electrodes

We report a nanoscale resistive random access memory (RRAM) device consisting of a NiO nanodot and graphene nanoribbon (GNR) nanogap electrodes. The GNR nanogap was established by an electroburning process induced by applying voltage ramp stress between the two ends of the GNR. A NiO nanodot was then deposited between the nanogapped GNR electrodes by an elaborately controllable dip pen lithography method using a nickel carbonate [Ni₂(CO₃)(OH)₂] solution. The nanoscale GNR/NiO/GNR RRAM device exhibited reliable unipolar resistive switching characteristics with low SET/RESET voltages and currents, which might be the result of its miniaturized size and well-defined Ohmic contacts between the NiO nanodot and GNR electrodes.     

Transformation of β-Ni(OH)2 to NiO nano-sheets via surface nanocrystalline zirconia coating: Shape and size retention

Shape and size of the synthesized NiO nano-sheets were retained during transformation of sheet-like β-Ni(OH)₂ to NiO at elevated temperatures via nano-sized zirconia coating on the surface of β-Ni(OH)₂. The average grain size was 6.42 nm after 600 °C treatment and slightly increased to 10 nm after 1000 °C treatment, showing effective sintering retardation between NiO nano-sheets. The excellent thermal stability revealed potential application at elevated temperatures, especially for high temperature catalysts and solid-state electrochemical devices.