基于零电荷电位调控的荷电炭材料用于逆电容去离子脱盐性能研究

Capacitive deionization (CDI) technology for desalination has drawn much attention because of its potential as an environmentally-friendly yet energy-efficient alternative to membrane desalination and thermal processes currently available for producing fresh water from salted water sources. However, the co-ion expulsion effect resulted from oxidation of anode electrode in CDI can lead to reduced salt removal capacity and charge efficiency, limiting its development. To overcome this difficulty, carbon electrodes based on the coordination of natural polyacids with completely different surface charge states were employed to develop a novel desalination system, called the inverted capacitive deionization (i-CDI) system. This project aims to deliver techniques that can greatly improve the adsorptive capacity and the regeneration of the carbon electrodes used in i-CDI processes. For this project, the main issues to be addressed include, but not limited: (1) to clarify the facile and sustainable synthetic strategy based on the coordination of natural polyphenols with metal ions, and develop for the textural engineering of mesocrystals and hierarchical carbon nanomaterials; (2) to clarify the co-ion expulsion effect and its controlled mechanism by modified potential of zero charge; (3) to use oxidation treatment, SiO2 modification and metal oxide, ionic liquid modificaiton to introduce negatively charged species and positively shift the Epzc of CDI electrode, respectively; (4) to study the interaction of the ions with microstructure, surface properties, potential of zero charge in the charged carbon electrodes and to understand the transport mechanism in the pore structures, and develop and establish strategies for the design and large scale fabrication of the charged carbon electrodes with different yet tuned structure and interface. The advantages achieved through this innovative work will lead to more efficient separation technologies across many sectors, such as desalination of saline, treatment of heavy metal ions in waste water and freshwater application.

电容去离子技术（CDI）是一种低耗高效环保的脱盐高新技术，然而由于阳极氧化产生的同名离子效应严重影响炭电极的循环再生性能，限制了其发展。本项目提出基于零电荷电位调控原理的逆电容去离子（I-CDI）新技术，并通过金属锌络合多元酸以及表面电荷的调控来构筑高性能荷电炭材料电极，从根本上消除同名离子效应，提高循环再生性能。研究内容主要包括:（1）金属锌络合多元酸制备层次孔炭材料的技术原理及其方法；（2）零电荷电位调控原理及消除同名离子效应的机制；（3）采用氧化法、SiO2包覆法制备荷负电炭材料作为I-CDI的阳极材料，并利用离子液体、双金属氧化物修饰法来构筑荷正电炭材料作为I-CDI的阴极材料，深入研究表面电荷控制的新型荷电炭材料电极构筑策略；（4）荷电炭材料电极物化性质与I-CDI脱盐构效关系、能量回收之研究及其相应调控技术策略的建立。项目的实施与发展有着重要的学术价值和广阔的应用前景。

电容去离子技术(Capacitive deionization, CDI) 是基于电化学原理的新型脱盐技术，然而由于阳极氧化产生的同名离子效应严重影响炭电极的循环再生性能，限制了其发展。本课题开展与发展了两种改进型电容去离子技术，一种是提出基于零电荷电位调控原理的逆电容去离子（I-CDI）新技术，主要通过表面电荷的调控来构筑高性能荷电炭材料电极，从根本上消除同名离子效应，提高循环再生性能。代表性文章发表在ACS Sustainable Chem. Eng (2019, 718, 15715); Desalination (2021, 505, 114979); 化工学报 (2022, 73, 1763)上。另外一种是采用可逆的法拉第赝电容原理进行杂化电容去离子技术(HCDI)的设计与构筑，典型的如采用HC@MnO2纳米线复合物并作为HCDI的阴极，所制备的HC@MnO2不仅具有高的电导率，又促进盐溶液渗透能力和扩散，从而增强了双电层与法拉第存储的协同效应。代表性文章发表在Environm. Sci. Technol.(2019, 53, 6292); ACS Nano(2021, 16, 1239)；Environm. Sci.: Nano(2019, 6, 2379)上。此外，本课题还针对水体中的氟离子(ACS Applied Mater. Interfaces, 2019, 11, 31200)，电镀废水中的铜离子(ACS EST Engineering, 2022, 2, 1722)等进行了选择性的脱除与资源化利用。总体上，本项目在探索电容去离子分离与资源化方面，从电化学角度上提出了两类改善电容去离子性能的策略，并在实践中充分挖掘适用与不同应用场所的关键材料制备方法，极大的推动了电容去离子脱盐技术的工业化进程；共计发表24篇论文，专利授权3件；培养6名研究生，两人次获得国家研究生奖学金。