摘要/Abstract
以乙酰丙酮镍、油酸、油胺为原料，十八烯为溶剂，聚乙烯吡咯烷酮为表面活性剂，采用溶剂热法，在不同反应条件制备了纳米级氧化镍材料.通过X射线衍射（X-ray diffraction，XRD）、透射电子显微镜（Transmission electron microscope，TEM）、紫外-可见光吸收光谱（Ultraviolet-visible spectroscopy，UV-Vis）光谱分析以及塔菲尔（Tafel）测试考察了反应物比例、保温时间、表面活性剂（PVP）、油胺的量对产物微结构、粒径、形貌、光学以及电化学活性性能的影响.实验结果表明：在反应物n[Ni（acac）2]∶n（OA）=1∶2、添加剂PVP质量分数为1.66%、油胺物质的量为30 mmol、200℃下保温8 h时，可获得粒径约为30～40 nm纯相氧化镍，具有最佳电化学活性，交换电流密度为J0=1.23×10-2 mA·cm-2.
关键词: 纳米NiO颗粒, 溶剂热法, 反应物比例, 表面活性剂, 结构形貌与光学性能
Nano-scale nickel oxide materials were prepared by solvothermal method using nickel acetylacetonate, oleic acid and oleylamine as raw materials, octadecene as solvent and polyvinylpyrrolidone as surfactant. The effects of the ratio of reactants ratio, insulation time, surfactant and the mass of oleylamine on the microstructure, particle size, morphology, optics and catalytic properties of the product were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM), ultraviolet-visible spectroscopy (UV-Vis) spectral analysis, and Tafel test. The specific experimental operations were:the oleic acid (OA) and 1-octadecene (ODE) was added into four flasks (500 mL) with heating and stirring. Nickel acetylacetonate was added when the temperature raise to 50℃, then continuously stirring for 60 minutes at 120℃ before a certain amount of oleylamine (OAm) was added to the reaction system. The mixed solution was poured into the inner liner of the high temperature reactor. The reactor was covered and transferred to the electro-thermostatic blast oven for a period of time and then cooled to room temperature. The main research results were obtained:(1) The boundary of the original particles became smoothed after sintering, and the spherical particles become flake-shaped which might be attributed to the residual organic covering so the size of nickel oxide nanoparticles changed from the original 40~45 nm to 30~40 nm. (2) With the addition of PVP, the content of NiO phase increased and the particle size was controlled within 40~45 nm. The UV-Vis test showed that NiO belonged to direct band gap and the band gap width was 3.5~3.7 eV. (3) The Tafel analysis showed that the best catalytic activity with exchange current density J0 was 1.23×10-2 mA·cm-2, where pure NiO could be obtained when the reactant ratio of n[Ni(acac)2]:n(OA)=1:2, the additive PVP mass fraction was of 1.66%, the amount of oleylamine was of 30 mmol, and the temperature was of 200℃ for 8 h.
Key words: NiO nanoparticles, solvothermal method, ratio of reactants, surfactant, microstructure and optical properties
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