金属氧化物多孔薄膜与水溶液界面交互作用机理研究

Naturally, the interaction of solid liquid interface widely exists. The study of metal oxide and aqueous solution interface is significant to the application of capacitive deionization. This work will be developed on the system of metal oxide porous membrane and aqueous solution. Through the measurement of zeta potential and open circuit potential, the mechanism that the interfacial electrical properties may be influenced by solution chemistry and the relationship between space charge and surface potential can be illustrated. This work will also focus on the varying properties of the pore water under the influence of solution chemistry by characterizing the refractive index with ellipsometer. The experimental results of refractive index and the molecular dynamic simulation results of the hydrogen bond varying with solution chemistry will be compared in order to discuss the mechanism of pore water affected by the interfacial properties. At last, based on the physical relationship among refractive index, dielectric constant and capacitance, different dielectric constants of the metal oxide porous membrane, together with the interfacial electrical properties and the pore water properties, having a coupled influence on the double layer capacitance will be studied. On account of interfacial interaction mechanism of metal oxide porous membrane and aqueous solution depicted above, specific metal oxide porous membrane and specific adsorption ions will be selected and asymmetric capacitive deionization structure will be designed to enhance the deionization performance.

固液界面交互现象在自然界中广泛存在，金属氧化物与水溶液界面交互作用的研究对于电容去离子技术应用具有重要意义。本项目针对金属氧化物多孔薄膜与水溶液界面交互作用展开分析。通过测量Zeta电位和开路电压表征界面离子浓度和电位分布，研究溶液性质对界面电性质的影响机理，阐明表面电位和空间电荷之间的关联规律。应用椭圆偏振光谱法分析微孔水折射率在不同溶液作用下的变化趋势，通过分子动力学模拟获得微孔水中氢键密度的变化规律，对比实验与模拟结果，揭示溶液性质对微孔水性质的影响机理。基于折射率、介电常数和电容三者之间的物理关系，耦合溶液性质对界面电性质和微孔水性质的影响机理，形成界面交互作用对双电层电容的影响规律。筛选特定的金属氧化物多孔薄膜和选择性吸附离子，构建基于界面交互作用机理的不对称电容去离子结构，实现去离子性能的提升。

固液界面交互现象在自然界中广泛存在，金属氧化物与水溶液界面交互作用的研究对于电容去离子技术应用具有重要意义。本项目针对金属氧化物多孔薄膜与水溶液界面交互作用展开分析，构建了开路电压与空间电荷和表面电位之间的关联模型，分析了溶液理化特性对表面电位与开路电压的影响机理。研究了Zeta电位和开路电压随pH的变化规律，磷酸根的吸附降低了其等电点；提出了零总电荷点处的开路电压的概念，通过探讨磷酸根离子对开路电压的影响，揭示了空间电荷在等电点处不等于零的机制并通过紫外实验进行了验证。通过干燥和一定湿度状态下的椭圆偏振光谱测试研究了表面电位对微孔水性质的影响机理。预处理离子强度增加导致微孔水折射率下降；表面电位绝对值越大，折射率越大，在等电点处，微孔水的折射率达到最低值；磷酸根离子的出现极大提高了微孔水的折射率。基于溶液理化特性对Zeta电位和界面电容的影响，揭示了表面电位对界面电容的影响机制。TiO2电极电容随pH的变化趋势与Zeta电位绝对值的变化基本一致；磷酸根的吸附在酸性环境下降低了Zeta电位绝对值，碱性环境下吸附量较低，均不能提高电容，而中性环境下提高了Zeta电位绝对值，使电容有一定的提升；提出了利用磷酸根改性后的TiO2和γ-Al2O3组成新型不对称电容去离子结构，覆涂金属氧化物的电极去离子能力增强。研究结果为金属氧化物纳米薄膜材料的基础研究提供了理论依据，也对超级电容器的设计以及电容去离子技术的改进提供了指导。