二氧化钛/氮掺杂石墨烯气凝胶的可控制备及电吸附脱盐性能研究

Degrading water quality problem and unreliable water supplies have been considered as major obstacles threatening the rapid urbanizing China. Water desalination is a key technology offering an appropriate route to improve the quality and quantity of pure water. Graphene aerogel is an excellent and novel candidate as a capacitive deionization (CDI) electrode material for its excellent characteristics, high surface area, environmentally safe. Incorporation of TiO2 nanoparticles into the graphene aerogel proved to be an effective approach to enhance the electro absorption, decrease polarization of the surface, and thus decrease physical adsorption of electrode. Moreover, nitrogen doped graphene has attracted intensive interest due to its good catalytic activity, high electrical conductivity, large surface area and good chemical stability. In this study, a novel TiO2/N-doped graphene aerogel (TGA) hybrid will be synthesized by a hybrid hydrothermal process. To evaluate the desalination behavior of TGA electrode, the proposed composite electrode was investigated under different factors during CDI process on NO3- solution. The influence of modifier proportion and experimental conditions on the ability of TGA electrodes will be examined. Electrochemical properties of TGA sample will be obtained by cyclic voltammetry, electrochemical impedance spectroscopy and constant current charge／discharge experiment．It is expected that TGA would have distinct performance due to unique designed of the nanofibrous morphology that avoids blocking pores surface and open interfacial pathway to increase the adsorption rate of ions from salt solution to electrode surface. The amount of incorporated TiO2 and nitride will be optimized to achieve the highest desalination efficiency. This study will be envisioned to fabricate a multifunctional graphene-based aerogel and promote their practical applications in water treatment.

我国的地下水存在大面积的硝酸盐污染问题，为防止饮用水中摄入过高的硝酸盐离子，新型、高效的脱盐处理技术的研发显得尤为重要。本研究拟针对硝酸盐离子在电极表面容易发生特性吸附而影响吸附-脱附效果的关键问题，考虑氮掺杂石墨烯对电极极大的电化学性能增强作用和半导体纳米管材料对电极空间结构调控的优点，设计二氧化钛/氮掺杂石墨烯气凝胶复合材料，对其进行结构调控，揭示气凝胶多尺度结构特性的形成机理。将新型石墨烯气凝胶与电吸附水处理技术结合，以硝酸盐离子为研究对象，揭示其物理、化学、双电层吸附和解附性能及机理，考察处理工艺的关键影响因素，为新型石墨烯气凝胶电极材料的可控制备及其电吸附水处理工程的应用提供科学依据和实验指导。

电极材料是电吸附法的基础，研究制备高性能的电极材料是电化学的前沿课题。本项目以氧化石墨烯为媒介材料，与选择的改性剂结合，通过水热还原自组装成功制备了氮掺杂石墨烯气凝胶、超长二氧化钛纳米管/氮掺杂石墨烯气凝胶、碳纳米纤维/氮掺杂石墨烯气凝胶、聚吡咯/氮掺杂石墨烯气凝胶等五种功能化石墨烯气凝胶，拓展了石墨烯基复合材料制备的途径和方法。以材料为基础，建立高效去除水中难降解污染物的三维电催化体系、双金属体系，在传统研究基础上进一步提高了反应速率，实现了石墨烯基材料在新型电催化领域应用上零的突破。通过对中间产物的定性分析，初步阐明污染物在不同体系下的降解途径与机理，提出的几种界面反应机制具有较高的学术价值，为深入理解电催化原理提供更多的理论支撑。在对多种污染物的去除研究基础上，提出污染物空间分布和源分配的生态风险评价系统，利用克里金插值方法和外推功能，表征各地质土层参数的变化规律, 对污染物的空间展布进行预测，开发出基于三维展布和重金属形态模拟的风险评价方法。