【作者】 王译莹；

【导师】 李庆；

【作者基本信息】 西南大学 ， 材料学， 2011， 硕士

【摘要】 本文采用简便、快速的微波辅助法通过抗坏血酸与高锰酸钾的氧化还原反应制备了分布均匀的α-MnO2纳米棒；以KMnO4为锰源,在[BMIM][PF6]离子液体水溶液中采用微波辅助加热法合成了α-MnO2纳米线；采用水浴加热法以p-环糊精为表面活性剂,在60℃水溶液中合成了形貌规整且尺寸分布均匀的由纳米片(平均厚度为5nm)插成的δ-MnO2花状球；通过液相化学法以十六烷基三甲基溴化铵(CTAB)为表面活性剂,在室温下水溶液中合成了CuS纳米空心球。用X-射线衍射仪(XRD)、X-射线能谱(EDX)、场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)、比表面积仪(BET)、热重分析仪(TG)、电化学方法(CV, LSV, CD, CP, Tafel)等手段对样品进行了分析和表征。主要内容如下：1.以高锰酸钾为锰源,抗坏血酸为还原剂,在0.5 M稀硫酸溶液中通过微波辅助法在160℃温度下加热30 min,得到了形貌规整且尺寸分布均匀的α-MnO2纳米棒,其平均直径为50nm、平均长度超过3μm。研究发现反应的时间和温度对产物的形貌有着重要的影响。通过热重曲线、循环伏安曲线以及恒电流充放电曲线对产物的热学和电学性能进行了表征,结果表明α-Mn02纳米棒具有良好的电化学性能,有望用于超级电容器阴极材料。2.以高锰酸钾为原料,在离子液体[BMIM][PF6]水溶液中采用与微波加热相结合的方法制备出平均直径为15 nm、平均长度为2μm的α-MnO2纳米线,长径比达130：1。基于实验结果,提出了纳米线生长的四步反应机理。用电化学方法对样品进行了表征,结果表明α-Mn02纳米线在碱性环境中的催化活性与商用Pt催化剂相似,有望作为阴极催化剂应用在燃料电池上。3.水浴加热法是一种合成纳米材料较简单普遍的方法。本论文中以可溶性淀粉和无水硫酸铜为反应原料,以β-环糊精为表面活性剂,在60℃水溶液中合成了形貌规整且尺寸分布均匀的由纳米片(平均厚度为5 nm)插成的δ-MnO2花状球。该花状球大小均匀、直径在500nm左右。经过平行的对比实验,说明β-环糊精在该花状球的形成过程中起着重要的作用。在0.5 M的Na2S04中性电解液中研究了产物的电化学性能,发现其电化学性能较高。4.本论文运用液相法以CuSO4?5H2O和硫代乙酰胺(TAA)为反应原料,以十六烷基三甲基溴化铵(CTAB)为表面活性剂,在室温下水溶液中合成了CuS纳米空心球。研究发现该空心球是由平均厚度为15 nm的纳米片插成的。基于实验结果,提出了CuS空心球的生K机理。通过XRD.FESEM.BET.BJH.CV.LSV及CP曲线对CuS空心球的结构及电化学性能进行了表征,结果表明具有孔道结构的CuS空心球(SBET=99.77 m2g-1)具有优异的电化学性能。更多还原

【Abstract】 In this dissertation, a facile and ultrafast microwave-assisted heating process has been developed to synthesize pure phaseα-MnO2 nanorods based on the redox reaction of KMnO4 and ascorbic acid; A microwave-assisted heating process has been developed to synthesize a-MnO2 nanowires based on the decomposed reaction of KMnO4 in ionic liquid([BMIM][PF6]) aqueous solution; Nanoflakes(with an average thickness of 5 nm) constructed 8-MnO2 flower-like nanospheres with a diameter of about 500 nm were prepared in water bath at 60℃usingβ-CD as a capping reagent; Nanoflakes(with an average thickness of 15 nm) constructed CuS hollow nanospheres with a diameter of about 500 nm were successfully prepared by a simple and efficient way with the aid of CTAB. The products were characterized by X-ray diffraction (XRD), X-ray spectra (EDX), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), Barrett-Joyner-Halenda (BJH), Thermo-gravimetric (TG), Cyclicvoltammetry (CV), Charging-discharging (CD), Linear sweep voltammtry (LSV), Chronopotentiometric (CP), Tafel techniques. The main points can be summarized as followed:1. We get the uniform pure phase a-MnO2 nanorods from potassium permanganate (KMnO4) and ascorbic acid (Vitamin C) with microwave irradiation heating at 160℃for 30 min in 0.5 M dilute sulfuric acid. The average diameter of theα-MnO2 nanorods is about 50 nm and length over 3μm. The reaction temperature and time were found to play important roles in formation of a-MnO2 nanorods. The product was characterized by TG, CV and CD curves. The results show that a-MnO2 nanorods exhibit excellent electrochemical characteristics. It’s possible that the a-MnO2 nanorods can be used as a cathode material in supercapacity. 2. By combing the advantages of both RTILs and microwave heating, a-MnO2 nanowires have been successfully synthesized. The results showed that the as-prepared a-MnO2 nanowires have a diameter of about 15 nm and a length of 2μm. Its length-diameter ratio is 130:1. A plausible four-step mechanism was proposed to explain the formation of a-MnO2 nanowires. The product was characterized by electrochemical methods. The results show thatα-MnO2 nanowires have similar electrochemical catalytic property as commercial Pt electrodeideal in alkaline solution. It’s possible that the a-MnO2 nanowires can be used as a catalyst in fuel cells.3. Water bath method is a popular method to prepare nanometer powders. Nanoflakes(with an average thickness of 5 nm) constructed 5-MnO2 flower-like nanospheres with a diameter of about 500 nm were prepared in water bath at 60℃usingβ-CD as a capping reagent. The results show that (3-CD plays a key role. The electrochemical properties of the as-prepared samples were utilized by cyclicvoltammetry curves in 0.5 M Na2SO4 neutral solution. The results show that a-MnO2 nanowires exhibited excellent electrochemical characteristics.4. CuS hollow nanospheres have been synthesized via liquid phase reduction method in the presence of cupric sulphate anhydrous (CuSO4·5H2O) with thioacetamide (TAA) in ethylene glycol (EG) under the assistance of cetyltrimethylammonium bromide (CTAB). The hollow nanospheres are composed of nanoflaks with a diameter about 15 nm. A possible growth mechanism of the CuS hollow nanospheres was proposed. The product was characterized by XRD, FESEM, BET, CV, LSV and CP. The results show that the porous CuS hollow nanospheres with special high BET surface area (99.77 m2 g-1) exhibited high electrochemical catalytic properties.更多还原