氢氧化镍纳米棒的水热制备及其表征

以Ni₂SO₄·6H₂O和NaOH为原料,在水热条件下制备了氢氧化镍纳米棒.运用透射电子显微镜(TEM)和X射线衍射仪(XRD)对样品进行了表征,考察了水热反应温度和pH值对产物的形貌和结构的影响.结果表明,氢氧化镍纳米棒形成的最佳条件是180～200℃,pH为9～10.     

铝钴复合掺杂的氢氧化镍的制备及其电性能

低热固相反应;氢氧化镍;电化学性能;复合掺杂     

氢氧化镍薄膜修饰玻碳电极的制备及其对L-赖氨酸氧化的电催化活性

采用恒电位沉积方法将氢氧化镍沉积到玻碳电极表面,得到稳定性高、催化活性好的氢氧化镍薄膜修饰玻碳电极;分析了影响薄膜形成过程的关键因素,确定了最佳薄膜制备方案;与此同时,将薄膜修饰玻碳电极用于生物样品L-赖氨酸的氧化测定,并探讨了其催化作用机理.结果表明,所制备的氢氧化镍薄膜修饰玻碳电极表面发生电化学反应[Ni(OH)2→NiOOH],从而促进电极表面的电子转移,实现对L-赖氨酸的电催化作用.当L-赖氨酸的浓度在1.0×10-4～4.0×10-7 mol/L范围内时,相应氧化峰电流与浓度呈线性关系,检出限达4.0×10-7 mol/L;据此可方便地制备稳定性好且灵敏度高的电流型传感器.     

碳布负载氢氧化镍电极材料的合成及其电容性能分析——推荐一个综合化学实验

作为超级电容器的电极材料,Ni(OH)₂具有理论比电容高、来源丰富、环境友好等优点,但较低的电导率影响了其实际性能。解决该问题的一种有效方法是在碳布导电基底上原位生长Ni(OH)₂薄膜。以此为基础设计综合化学实验,通过Ni(OH)₂/碳布薄膜电极的制备、表征及电化学性能测试,使学生进一步理解化学平衡原理在材料合成中的应用,了解材料的基本表征方法,掌握循环伏安法、恒流充放电法等电化学分析方法在实际测试中的运用与解析,从而达到巩固电化学理论知识、培养学生的实验技能、提高学生综合实验能力的目的。本实验的开展还可以帮助学生了解储能领域的科技前沿,激发学生的科研兴趣,培养学生的科研创新意识,适合在大学化学实验中推广应用。     

密度泛函理论及其数值方法新进展

综述了密度泛函理论及其数值方法的最新进展.密度泛函理论的发展以寻找合适 的交换相关近似为主线,从最初的局域密度近似、广义梯度近似到现在的非局域泛函、自相 互作用修正,多种泛函形式的相继出现使得密度泛函理论可以提供越来越精确的计算结果. 除了交换相关近似的发展,近年来密度泛函理论向含时理论、相对论等方面的扩展也很活跃 .另外,在密度泛函理论体系发展的同时,相应的数值计算方法的发展也非常迅速.从古老 的有限差分、有限元到新兴的小波分析都被用来实现密度泛函理论的数值计算.与此同时, 线性标度的密度泛函理论算法日趋成熟,使得通过密度泛函理论研究诸如生物大分子之类的 体系成为可能.随着密度泛函理论本身及其数值方法的发展,它的应用也越来越广泛,一些新的应用领域和研究方向不断涌现.     

新潜在高能量密度化合物（HEDC）多硝酸酯基金刚烷由气态到固态的理论研究

为寻求新的潜在高能量密度化合物（HEDCs）,对系列（26个）多硝酸酯基金刚烷进行由气态到固态的理论研究.在B3LYP/6-31G水平下,通过设计合理的等键反应,求得26个标题物的生成热（HOFs）,其结果表明：具有相同—ONO2基数目（n）的同分异构体的HOFs值与取代基的位置相关性不好,即并非取代基间距离越近,其HOF越大.基于所求HOFs和理论密度（ρ）,运用修正的适合CHNO系的Kamlet-Jacobs方程,估算了该26个化合物的爆炸性质（能量性质）：爆热（Q）、爆速（D）和爆压（P）,结果表明：当n=7-8时,对应硝酸酯基金刚烷符合HEDC的能量要求,即ρ〉1.9g·cm^-3,D〉9.0km·s^-1,P〉40.0GPa.为考虑HEDC的适用性,对两种可能引发键（C—O和O—NO2）离解能（EC—O和EO—N）进行计算和比较发现EC—O总是小于EO–N,这表明O—NO2为该系列化合物的热解引发键;且发现具有偕二硝酸酯基的金刚烷在同分异构体中的热稳定性总是最差,并且所有偕二硝酸酯基金刚烷的稳定性均相当;由于该系列化合物结构的复杂性,随化合物中取代基数（n）的增加,化合物的EO–N并不明显降低,且该系列化合物的稳定性并非由某个结构参数决定.因而,结合HEDC的能量和稳定性要求（引发键离解能〉12kJ·mol^-1）,仅1,2,4,6,8,9,10-七硝酸酯基金刚烷被推荐为潜在品优HEDC.运用分子力学（MM）方法,分别以Compass和Dreiding力场,在七种最可几空间群（P21/c,P-1,P212121,P21,Pbca,C2/C和Pna21）中,对1,2,4,6,8,9,10-七硝酸酯基金刚烷分子的堆积方式进行预测.两种力场的预测结果均表明,该化合物属P21/c空间群.进行对该预测晶胞的电子结构的周期性从头算,报道其能带结构和态密度,关联其稳定性.发现Fermi能级附近的能带主要由—O—NO2的O和N原子的p态所贡献,且—NO2中N和—O—的p态相重叠形成O—NO2键;这与其气相分子键离解能计算结果相一致,即O—NO2键为该系列化合物的热解引发键.     

靛蓝及其取代物的密度泛函理论研究

运用量子化学中密度泛函理论(DFT)方法,在B3LYP／6-31G^ 水平上对靛蓝及其芳环4,4′-,5,5′-,6,6′-,7,7′-取代衍生物进行理论计算．探讨了F,Cl,Br,NO2,CH3O,CH3在不同位置的取代对分子的几何构型、电子结构和电子光谱的影响,获得与实验结果相一致的结论．还用含时密度泛函理论(TD-DFT)方法在相同水平计算其电子光谱．结果表明靛蓝及其芳环取代衍生物的最低激发单重态(S1)均源自HOMO-LUMO(π-π^*)跃迁．     

沉淀制备双酚Aπ-π堆积自组装印迹聚合物及其特异性识别机理研究

以类雌性激素双酚A为模板分子,选取4-乙烯基吡啶作为功能单体,在极性溶剂甲醇中,通过非共价键完成自组装过程,沉淀聚合制备对双酚A分子具有高度选择性识别和亲和力的分子印迹聚合物.采用紫外-可见光谱研究了双酚A和4-乙烯基吡啶的配合方式以及配位比,结果表明双酚A与4-乙烯基吡啶以配位比1∶2的方式,在极性溶剂中,无法以常用的氢键形成超分子配合物,却可以π-π堆积这种非共价键完成自组装过程.通过红外谱图,验证了沉淀聚合法制备的印迹聚合物可以完成双酚A的印迹和可逆分离.通过扫描电镜和等温吸附实验考察了分子印迹聚合物对模板分子的特异性识别和选择性吸附机理,印迹聚合物的特异性吸附容量为37.39μmol/g,印迹指数为4.31;对其结构类似物四溴双酚A和苯酚的分离因子分别为2.51和2.06,同时对莠去津,萘普生和槲皮素的分离因子分别为2.14,2.26和2.63,证实了分子印迹聚合物在极性溶剂中可以对双酚A分子进行很好的特异性识别,并且识别环境更接近天然分子环境.     

青蒿素及其衍生物抗疟活性的密度泛函理论研究

为了深入研究青蒿素及其衍生物的抗疟活性和分子结构之间的关系,运用密度泛函理论B3LYP方法,以6-31G*为基组对青蒿素及其衍生物二氢青蒿素、蒿甲醚和青蒿琥酯进行了优化计算.从分子的几何构型、NBO电荷及前线轨道能等方面分析了青蒿素及其衍生物的抗疟活性与结构之间的关系.青蒿素及其衍生物结构中的过氧桥键是其抗疟作用的活性位,O17和O_20带负电荷越多、ΔE_(LUMO-HOMO)越低、E_(HOMO)能级越高,分子的抗疟活性越强.结果表明,4种化合物的抗疟活性顺序为:青蒿素二氢青蒿素蒿甲醚青蒿琥酯,与临床实验结果相吻合.     

嘧啶及其异构体的密度泛函理论研究

胞嘧啶、尿嘧啶和胸腺嘧啶都有酮式和烯醇式互变异构。有人认为DNA的错配频率,与酮,烯醇或氨,亚氨的互变异构平衡有关。迄今,在相同理论水平上同时对三种嘧啶互变异构体进行理论计算研究的文献较少,     

Controllable synthesis of nickel hydroxide and porous nickel oxide nanostructures with different morphologies

Alpha-Ni(OH)(2) nanobelts, nanowires, short nanowires, and beta-Ni(OH)(2) nanoplates have been successfully prepared in high yields and purities by a convenient hydrothermal method under mild conditions from very simple systems composed only of NaOH, NiSO(4), and water. It has been found that the ratio of NaOH to NiSO(4) not only affects the morphology of the Ni(OH)(2) nanostructures, but also determines whether the product is of the alpha- or beta-crystal phase. A notable finding is that porous NiO nanobelts were produced after exposure of the Ni(OH)(2) products to an electron beam for several minutes during transmission electron microscopy (TEM) observations. Another unusual feature is that rectangular nanoplates with many gaps were obtained. Furthermore, porous NiO nanobelts, nanowires, and nanoplates could also be obtained by annealing the as-prepared Ni(OH)(2) products. A sequence of dissolution, recrystallization, and oriented attachment-assisted self-assembly of nanowires into nanobelts is proposed as a plausible mechanistic interpretation for the formation of the observed structures. The method presented here possesses several advantages, including high yields, high purities, low cost, and environmental benignity. It might feasibly be scaled-up for industrial mass production.     

Co取代Ni(OH)2纳米粉体的制备、表征及电化学性能研究

本文利用固相反应制备了不同取代量的Co取代Ni(OH)2纳米样品。X射线衍射、透射电镜测试结果表明所得样品均为β-Ni（OH）2，粒子呈球形，粒径大小在40nm左右。TG－DTA热分析结果表明，温度高于200℃时，Ni(OH)2开始不可逆的分解为NiO。循环充放电、循环伏安及Tafel极化等电化学测试结果表明适量Co的掺入，降低了电极内阻，提高了电极反应的可逆性，抑制了析氧过程的发生，提高了电极的充电效率，并使其放电容量与循环寿命得到了明显改善。     

Ball-milling processing of nanocrystalline nickel hydroxide and its effects in pasted nickel electrodes for rechargeable nickel batteries

Nanocrystalline Ni(OH)₂ powder synthesized by a chemical precipitation method was processed using the planetary ball milling (PBM), and the physical properties of both the ball-milled and unmilled Ni(OH)₂ were characterized by scanning electron microscopy (SEM), specific surface area, particle size distribution, and X-ray diffraction. It was found that the PBM processing could significantly break up the agglomeration, uniformize the particle size distribution, increase the surface area, decrease the crystallite size, and reduce the crystallinity of nanocrystalline β-Ni(OH)₂, which were advantageous to the improvement of the electrochemical activity of Ni(OH)₂. The ball-milled nanocrystalline (BMN) Ni(OH)₂ was then used to alter the microstructure of pasted nickel electrodes and improve the distribution of the active material in the porous electrode substrate. Electrochemical performances of pasted nickel electrodes with a mixture of BMN and spherical Ni(OH)₂ as the active material were investigated, and were compared with those of pure spherical Ni(OH)₂ electrodes. Charge/discharge tests showed that BMN Ni(OH)₂ addition could enhance the charging efficiency, specific discharge capacity, discharge voltage, and high-rate capability of pasted nickel electrodes. This performance improvement could be attributed to a more compact electrode microstructure, better reaction reversibility, and lower electrochemical impedance, as indicated by SEM, cyclic voltammetry, and electrochemical impedance spectroscopy. Thus, it was an effective method to modify the microstructure and improve the electrochemical properties of pasted nickel electrodes by adding an appropriate amount of BMN Ni(OH)₂ to spherical Ni(OH)₂ as the active material.     

Al掺杂Ni(OH)2的结构及电化学性能

用化学共沉淀法合成了A l掺杂N i(OH)2,用XRD表征了合成样品的结构特征:研究了合成样品的循环伏安性能,以及用A l掺杂N i(OH)2为正极活性物质的Zn/N i试验电池的充放电性能。研究结果表明:所合成的A l掺杂N i(OH)2为具有α-型晶体结构的材料,A l掺杂N i(OH)2具有优良的电化学可逆性、良好的充放电性能和较好的电化学循环性能;A l掺杂N i(OH)2作为正极活性物质的Zn/N i试验电池等250次充放电循环容量保持率130.1%,最高放电比容量为420.5mAh/g。     

聚邻苯二胺/镍氢氧化物修饰电极的研究

采用循环伏安法(CV)在聚邻苯二胺修饰玻碳电极表面络合Ni2+,然后将其置于NaOH溶液中CV扫描成功制备了镍氢氧化物/聚邻苯二胺/玻碳修饰电极(Ni(OH)2/PoPD/GC).通过CV探讨了聚合和负载机理,电化学交流阻抗谱(EIS)表征了电极修饰过程中界面阻抗变化,扫描电镜表征了PoPD膜负载Ni(OH)2后的形态...     

The effect of ‘crystallinity’ and structural disorder on the electrochemical performance of substituted nickel hydroxide electrodes

β_bc-Nickel hydroxide exhibit non-uniform broadening reflections in their PXRD pattern due to the presence of structural disorder. β_bc-Nickel hydroxide electrodes with smaller crystallite size and structural disorder reversibly exchanges 0.9e/Ni. Co/Zn/Ca/Cd-substituted β_bc-nickel hydroxide samples also display non-uniform broadening of reflections in their powder X-ray diffraction patterns with smaller crystallite size and exchanges 0.7–0.8e/Ni. Hydrothermal treatment of β_bc-nickel hydroxide slurry at 170 °C results in an ordering of reflections in their powder X-ray diffraction pattern with an increased crystallite size. Crystalline β-nickel hydroxide electrode reversibly exchanges 0.3–0.4e/Ni. Hydrothermal-treated Co/Zn/Ca/Cd-substituted β_bc-nickel hydroxide slurries at 170 °C display sharp reflections with similar crystallite size and electrochemical activities as that of crystalline β-nickel hydroxide. This clearly demonstrates that partial substitution of Co/Zn/Ca/Cd in the nickel hydroxide matrix does not show any dramatic improvement in their electrochemical activity at 25–30 °C. Structural disordered material with smaller crystallite size delivers electrochemical activity close to theoretical capacity.     

高性能球型氢氧化亚镍的ICP-OES分析方法

建立了镍氢电池正极材料氢氧化亚镍中主成分锌、钴及杂质钙、镁、锰、镉的ICP AES测定方法。选择了仪器最佳工作条件 ,研究了镍基体对被测元素的干扰。方法的回收率为 95 .9%～ 1 0 3% ,RSD为 0 .93%～ 1 8%。     

高比表面积介孔氧化镍制备及表征

采用硝酸镍和草酸为原料,采用固态热分解法制备得到高比表面积的介孔Ni O纳米粒子,考察了原料的用量,热处理的温度,热处理的时间对孔结构的影响。用X射线衍射、透射电镜、扫描电镜和N2吸附-脱附技术对材料的物化性质进行了表征。结果表明:硝酸镍和草酸1∶1混合均匀、400℃灼烧4 h得到的介孔Ni O粒子的孔结构为最发达的蠕虫状介孔结构,比表面积和孔容分别达到236 m2·g-1和0.42 cm3·g-1。     

Mathematical models of the nickel hydroxide active material

A review is presented of the mathematical models that have been developed to describe the phenomena that occur in the active material in the nickel electrode. The review includes models that describe the reaction thermodynamics, proton diffusion, electron conductivity, semiconductor effects, and the reactions in the solid phase. The appropriateness of these models and their usefulness in predicting phenomena observed in nickel-based batteries are discussed. Received: 17 October 1999 / Accepted: 26 December 1999