【作者】 张熊；

【导师】 杨文胜；

【作者基本信息】 北京化工大学 ， 应用化学， 2008， 博士

【摘要】 本论文以二氧化锰材料为研究对象,采用水热方法合成一系列不同晶型和形貌的二氧化锰材料;针对其中的层状二氧化锰可插层和可剥离的性质,采用长链烷基铵插层二氧化锰材料为前体,制备聚合物与二氧化锰纳米复合材料,并对其电化学及光学性能进行了研究;采用层板剥离技术,制备二氧化锰纳米片,并以其为构建模块,分别采用静电组装技术和电泳沉积法制备了二氧化锰无机—无机和有机—无机复合薄膜材料。采用X射线衍射（XRD）、电感耦合等离子体原子发射光谱（ICP-AES）、傅立叶变换红外光谱（FTIR）、紫外可见光谱（UV-vis）、X光电子能谱（XPS）、热重-质谱联用（TG-MS）、透射电镜（TEM）、高分辨透射电镜（HRTEM）、场发射扫描电镜（FESEM）、原子力显微镜（AFM）和电化学测试等表征手段对合成产物、反应机理以及材料的组成结构与电化学及光学性能之间的关系进行了较深入的研究。采用水热法合成了一系列不同晶型的二氧化锰纳米材料,包括α、β、Na[2×4]一维隧道型二氧化锰,δ型层状二氧化锰,无定型二氧化锰。对于KMnO₄-MnSO₄反应体系,通过调变水热处理时间或起始反应物的浓度,实现了具有不同晶型和形貌的二氧化锰的可控合成。在160℃水热反应处理8h,可以得到α-MnO₂纳米线;继续延长反应时间至72 h,可以得到具有棱柱状形貌的β-MnO₂微晶。在水热反应过程中,α-MnO₂纳米线由于取向堆积自发形成大的团束,随后发生晶型转变,形成β-MnO₂微晶。KMnO₄-MnSO₄反应体系在160℃水热处理30min后,可以得到一种无定型介孔二氧化锰纳米材料。比表面积高达196 m²·g^-1,最可几孔径分布为3.7 nm。在1 mol·L^-1的Na₂SO₄水溶液中测试其电化学性能,比电容可达323 F·g^-1,且倍率特性好,恒流充放电循环测试3000次后,比电容的保持率为96%。对于H₂O₂-Mn（NO₃）₂-NaOH反应体系,通过调变水热处理温度,分别可以得到不同晶型二氧化锰产物。在120℃水热反应处理16h,可以得到Na-birnessite型层状二氧化锰;在200℃水热反应处理16h,可以得到Na[2×4]一维隧道型二氧化锰,且产物具有特殊的纳米带状形貌。提高水热处理温度,有利于形成隧道型二氧化锰。采用剥离重组法,即将十八烷基三甲基铵插层二氧化锰在N-甲基吡咯烷酮溶剂中超声剥离,再与导电聚合物（聚吡咯和聚苯胺）复合,制备了导电聚合物插层二氧化锰纳米复合材料,并对其作为超级电容器电极材料的电化学性能进行了研究。纳米复合材料表现出比单个组分更加优越的电化学性能,这是由于将导电聚合物与二氧化锰材料复合,可以提高复合材料的导电率;同时,导电聚合物可以将二氧化锰层板撑开,提高了复合材料的空隙率,有利于离子在电极材料中的扩散。聚苯胺插层二氧化锰复合材料的比电容为330 F·g^-1,而单纯的层状二氧化锰和聚苯胺的比电容分别为208 F·g^-1和187 F·g^-1。此外,复合材料的电化学循环性能比单个组分也明显得到改善。采用熔融共混法,通过将双十八烷基二甲基铵插层二氧化锰与线性低密度聚乙烯（LLDPE）混合制备了LLDPE/MnO₂纳米复合材料。熔融处理10 min可以得到LLDPE插层二氧化锰复合材料,延长熔融处理时间至30 min,可以得到完全剥离型的LLDPE/MnO₂纳米复合材料。LLDPE/MnO₂剥离型纳米复合材料表现出良好的紫外屏蔽性能和热稳定性,这可能与剥离MnO₂纳米片在LLDPE本体中分子级别的分散以及纳米片材料的二维尺寸效应有关。采用静电组装技术,分别制备了水滑石纳米片/二氧化锰纳米片无机多层复合薄膜和聚乙烯亚胺/二氧化锰纳米片有机—无机多层复合薄膜（PEI/MnO₂）_n。UV-vis光谱显示薄膜的增长十分均匀。我们考察了（PEI/MnO₂）_n复合薄膜作为超级电容器电极材料的电化学性能。随着（PEI/MnO₂）_n层数的增加,薄膜的比电容线性增加。（PEI/MnO₂）₁₀薄膜电极的比电容为288 F·g^-1,循环1000次后,比电容保持率为90%。采用超声处理的方法,成功实现了四甲基铵插层二氧化锰在乙腈有机溶剂中剥离;采用电泳沉积法,以含有剥离二氧化锰纳米片的乙腈溶剂为电解液,在氧化铟锡导电玻璃上制备了（00l）取向的层状二氧化锰薄膜。更多还原

【Abstract】 Manganese oxide materials with different crystalline structures and morphologies have been synthesized by a hydrothermal method.Due to the intercalated and exfoliated characteristic of layered manganese oxides, polymer with manganese oxide nanocomposites have been prepared by using long alkylammonium intercalation manganese dioxide as precursors, and their electrochemical or optical properties were studied.MnO2 nanosheets obtained by delaminating the layered manganese oxide can be used as the building blocks to fabricate inorganic or organic -inorganic nanocomposite films through the electrostatic layer-by-layer adsorption technique or electrophoretic deposition.Reaction conditions,mechanisms, the relationships among structure,composition and electrochemical or optical properties of materials were characterized by means of XRD, ICP-AES,UV-vis,FT-IR,XPS,TG-MS,TEM,HRTEM,FESEM,AFM and electrochemical test.A series of different crystallines of manganese oxide nanomaterials, includingα-,β- and Na[2×4]type one-dimensional tunnel manganese oxides,δ-type layered manganese oxide,and amorphous manganese oxide, were prepared by a hydrothermal method.For KMnO₄-MnSO₄ reaction system,the products with different crystalline structures and morphologies can be selectively formed by varying the hydrothermal reaction time and the initial reactant concentration.After hydrothermal treatment for 8 h at 160℃,α-MnO₂ nanowires can be obtained;Elongating hydrothermal time to 72 h,β-MnO₂ microcrystals with a prismatic morphology were obtained. Under the process of hydrothermal reaction,α-MnO₂ nanowires became self-assembled into bundles and subsequently underwent a phase transformation toβ-MnO₂ microcrystals.When hydrothermal treated for 30 min,amorphous mesoporous manganese oxide nanomaterials can be obtained.The products showed a BET surface area of 196 m²·g^-1and a narrow pore size distribution of 3.7 nm.A specific capacitance value of 323 F·g^-1was obtained in 1 mol·L^-1Na₂SO₄ solution.After 3000 cycles of operation,the capacitance retention was 96%of initial value.For H₂O₂-Mn（NO₃）₂-NaOH reaction system,the hydrothermal temperature is critical to the crystalline structure of final products.The product of Na-birnessite was obtained at 120℃,and Na[2×4]one-dimensional tunnel manganese oxides nanobelts was obtained at 200℃.Increase hydrothermal temperature was conducive to formation of tunnel-type manganese oxides.Conducting polymer-intercalated layered manganese oxide nanocomposites were synthesized via exchange reaction of conducting polymers（polyaniline and polypyrrole）with n-octadecyltrimethylammonium-intercalated manganese oxide in N-methyl-2-pyrrolidone solvent by a delamination/reassembling process,and their electrochemical properties as electrode materials for supercapacitors were studied.The resulting nanocomposites possessed superior electrochemical performance than each pristine component,which was due to intercalation of conducting polymers into manganese oxide can improve the electrical conductivity and bidimensionality.Polyaniline-intercalated manganese oxide nanocomposites showed a specific capacitance of 330 F·g^-1,which was much larger than the values of layered manganese oxide(208 F·g^-1)and polyaniline(187 F·g^-1).In addition,the electrochemical cycle performance of the nanocomposites significantly improved than the single component.Linear low-density polyethylene（LLDPE）/layered manganese oxide nanocomposites（LLDPE/MnO₂）were synthesized by direct melt compounding of LLDPE in the organic modified layered manganese oxides with dioctadecyldimethylammonium cations.When the melt compounding time was 10 min,the LLDPE intercalated layered manganese oxides nanocomposites were obtained.Elongating the melt compounding time to 30 min,the completely exfoliated LLDPE/MnO₂ nanocomposites could be obtained.The LLDPE/MnO₂ exfoliation nanocomposites showed high UV-shielding efficiency and enhanced thermal stability,which can be attributed to the molecular dispersion of MnO₂ nanolayers in the LLDPE matrix.Inorganic multilayer thin films comprising MnO₂ nansheets and LDHs nanosheets,and organic-inorganic multilayer thin films（PEI/MnO₂）_n comprising polyethylenimine（PEI）and MnO₂ nanosheets,were prepared by the electrostatic layer-by-layer adsorption technique.UV-vis spectra showed the multilayer films increased uniformly.The electrochemical properties of（PEI/MnO₂）_n multilayer films were studied.The area specific capacitance values of（PEI/MnO₂）_n films enhanced almost linearly with increasing in the number of bilayers.A specific capacitance value of 288 F.g^-1was obtained for（PEI/MnO₂）₁₀film,and the capacitance decreased 10 %of initial value over 1000 cycles.Delamination of layered manganese oxide into colloidal nanosheets occurred when manganese oxide intercalated with tetramethylammonium ions was ultrasonically dispersed in acetonitrile organic solution.An oriented layered manganese oxide thick film with（00l）plane parallel to the substrate was obtained by electrophoretic deposition of negatively charged manganese oxide nanosheets on ITO-coated glass substrate.更多还原