【作者】 丹媛媛；

【导师】 林海波；

【作者基本信息】 吉林大学 ， 物理化学， 2011， 博士

【摘要】 PbO2是一种被广泛应用的电极材料,具有高导电性、高化学稳定性、良好的耐蚀性、可通过大电流、价格低廉等优点。若能将一些具有特定功能的纳米微粒均匀分散在PbO2基质中,由于纳米微粒与PbO2之间的协同效应,从而可制备出一些具有特殊性能的PbO2基纳米氧化物复合电极材料。本文通过低温一步合成法和水热法分别制备了Co3O4纳米粒子、Mn3O4纳米粒子、WO3纳米片和SnO2纳米粒子,采用电化学复合共沉积技术,在钛基体上可控制备了nano-Co3O4+PbO2、nano-Mn304+PbO2、nano-WO3+PbO2和nano-SnO2+PbO2等四种PbO2基纳米金属氧化物复合功能电极材料,并且对四种复合电极材料的制备工艺、结构、组成、电化学性能和应用进行了详细的研究。结果表明,制备的四种PbO2基纳米金属氧化物复合功能电极材料在电催化和储能等方面表现出良好的性能。电化学复合共沉积过程在三电极体系中进行恒压施镀。其镀液的pH为3～4,镀液中含有0.1 mol/L Pb(NO3)2和一定量稳定悬浮的纳米微粒。研究发现,纳米粒子／纳米片的嵌入量随溶液中微粒含量的增大而增大,并趋于极限值；最佳沉积电位为1.4 V；最佳沉积体系为20%丙酮+80%水溶液；最佳沉积时间为2 h；最佳沉积温度为室温。Nano-Co3O4+PbO2复合电极材料是由尖晶石结构的Co3O4和β-PbO2组成。随纳米Co3O4掺杂量的增大,复合材料的晶粒尺寸随之减小,孔隙率、比表面积随之增大。由于多孔性和组分间的电子协同效应,该复合电极材料在碱性介质中具有良好的析氧活性和赝电容性能。其析氧电位随Co3O4掺杂量的增大而降低,最大可降低约160 mV；复合电极材料的电容性能为最佳,其比电容值可达约220 F/g。Nano-Mn3O4+PbO2复合电极材料是由四方相y-Mn3O4与β-PbO2所组成的复合物。同未掺杂nano-Mn3O4的PbO2电极相比,复合电极材料的晶体颗粒小孔隙率高,具有准三维多孔特性,比表面积大,其有效电化学面积比最高可达72。高电化学有效面积以及nano-Mn3O4与PbO2之间的协同作用,使nano-Mn3O4+PbO2复合电极材料在中性介质中,具有优良的析氧活性和赝电容性能。其析氧活性和赝电容性能随Mn3O4含量的增加而增加,析氧电位最大可降低约500 mV,其比电容值最高约可达340 F/g。Nano-WO3+PbO2复合电极材料是由WO3·H2O与β-PbO2所组成的复合物。随着nano-WO3掺杂量的增大,复合电极材料的晶体颗粒尺寸随之减小、孔隙率随着提高,表面积随之增加,其有效电化学面积比最高可达57。高电化学有效面积以及WO3·H2O纳米片与PbO2之间的协同作用,使nano-WO3+PbO2复合电极材料在酸性介质中,具有良好的析氧活性和优良的赝电容性能。随nano-WO3掺杂量的增加,初始析氧电位负移幅度随之增大,比电容值也随之增大,其起始析氧电位最大可降低约200 mV,比电容值最高可达320 F/g。Nano-SnO2+PbO2复合电极材料是由四方金红石相SnO2与β-PbO2所组成的复合物。同未掺杂SnO2的PbO2电极相比,复合电极材料的晶体颗粒小,因而其比表面积增加。复合电极材料的起始析氧电位表明,nano-SnO2+PbO2复合电极材料与纯SnO2和PbO2的析氧活性相近,初始析氧电位都在1.9 V～2.0 V之间,是一种析氧电位较高的电极材料,适宜作为阳极材料应用在电氧化反应中。较大的比表面积以及SnO2纳米粒子与PbO2之间的协同作用,使nano-SnO2+PbO2复合电极材料在酸性水溶液超级电容器中,具有优良的赝电容性能,其比电容值最高可达208 F/g。更多还原

【Abstract】 PbO2 is widely employed as an anode in the chemical industry, as it has high conductivity, excellent corrosion resistance, chemical stability, high current tolerance and low cost. If the functional nanomaterials could be dispersed into PbO2 matrix, they would benefit each other through synergetic effects arising from the intimate electronic interaction of the components. The novel PbO2 matrix composite electrode materials will have special properties.In this study, we have synthesized nano-Co3O4, nano-Mn3O4, nano-WO3 and nano-SnO2, respectively, via one-step homogeneous precipitation at low temperature and hydrothermal synthesis method. Subsequently, the nano-Co3O4+PbO2, nano-Mn3O4+PbO2, nano-WO3+PbO2 and nano-SnO2+PbO2 composite electrode materials are prepared by anodic composite electrocodeposition on Ti substrate. Furthermore, we have studied the controllable preparation conditions, structure, composition, electro-properties and applications of these four composites in detail. The resultes indicate that the novel PbO2 matrix composite electrode materials have promising application potentials in the fields of electro-catalytic and storage.Electrolytic deposition of composite oxides was performed in a three-electrode electrolytic cell under constant-potential control. The 100 mL of electrolytic solution consisted of 0.1 mol/L Pb(NO3)2 and suspended nano-particles/sheets, the pH value of the electrolyte is about 3～4. It is found that the embedded nano-particles/sheets concentration is increased with the increasing concentration of the nano-particles/sheets suspended in the planting. However, the content of the particles/sheets embedded increased to a limiting value. The optimal preparation conditions for the composites were as follows:deposition potential is 1.4 V; electrolytic solution consisted of 20% acetone and 80% water; deposition time is 2 h; deposition temperature is room temperature.The composite on the electrode surface is composed of spinel nano-Co3O4 andβ-PbO2. Composite porosity and specific area increase and the grains decrease with the nano-Co3O4 doping content increasing. The composite shows excellent activity for OER (oxygen evolution reaction) and high-capacity in alkaline medium, owing to the intimate electronic interaction between PbO2 and nano-Co3O4, and the porosity of the composite. Electrical tests indicate that the overpotentials of the composites for OER shift to the negative, whereas the onset potential (Eonset) decreases by approximately 160 mV to the maximal degree. The nano-Co3O4+PbO2 composite shows the highest specific capacitance up to～220 F/g.The nano-Mn3O4+PbO2 composite is composed of tetragonalγ-Mn3O4 andβ-PbO2. Composite porosity and specific area increase and the grains decrease with the nano-Mn3O4 doping content increasing. It is a porous quasi-3D material with a maximum electrochemically effective area ratio (RF) of 72. The composite shows excellent activity for OER and high-capacity in neutral medium. This could be attributed to the intimate electronic interaction between PbO2 and nano-Mn3O4, and the porous quasi-3D structure of the composite. The activity for OER and capacity is improving with the embedded nano-Mn3O4 increasing. The Eonset decreases by approximately 160 mV to the maximal degree. The nano-Mn304+Pb02 composite shows high specific capacitance up to～340 F/g.The nano-WO3+PbO2 composite is composed of WO3·H2O andβ-PbO2. Composite porosity and specific area increase and the grains decrease with the nano-WO3 doping content increasing. It is a porous material with a maximum electrochemically effective area ratio (RF) of 57. The composite shows excellent activity for OER and high-capacity in acidic medium. This could be attributed to the intimate electronic interaction between PbO2 and nano-WO3, and the porous structure of the composite. The activity for OER and capacity is improving with the embedded nano-WO3 increasing. The Eonset decreases by approximately 200 mV to the maximal degree. The nano-WO3+PbO2 composite shows high specific capacitance up to～320 F/g.The nano-SnO2+PbO2 composite is composed of rutile phase SnO2 andβ-PbO2. Composite specific area increase and the grains decrease with the nano-SnO2 doping content increasing. The Eonset of the composite is similar to SnO2 andβ-PbO2, which is about 1.9 V～2.0 V. Owing to the intimate electronic interaction between PbO2 and nano-SnO2, the nano-SnO2+PbO2 composite shows high specific capacitance up to～208 F/g.更多还原