Pseudocapacitive deionization with nanolamellar metal carbides (MXene CDI)

使用纳米层状金属碳化物 (MXene CDI) 进行赝电容去离子

• 批准号: 404260730
• 负责人: Professor Dr. Volker Presser
• 金额: --
• 依托单位: Leibniz-Institut für Neue Materialien gGmbH (INM)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/404260730?language=en
• 关键词: Pseudocapacitive; deionization; nanolamellar; metal; carbides

Capacitive deionization (CDI) is an emerging technology, promising high efficiency and low energy consumption for the removal of ions from aqueous media with low molar concentration (below 100 mM). By this virtue, CDI is particularly attractive for deionization of brackish water or industrial water streams. The process of CDI is similar to the operation of double-layer capacitors (supercapacitors): ions are electrosorbed onto the surface of highly porous electrodes and effectively removed from the feed water stream. Regeneration of the electrodes is then accomplished by discharging or voltage reversal. Until now, the majority of works in the field of CDI has been limited to the synthesis, analysis, and application of nanoporous carbon considering the high surface area and relatively high chemical stability. With the focus on carbon, most works have explored purely electrostatic deionization by ion immobilization via electrochemical double layers. This is why mostly carbon as a capacitive material has been applied for CDI so far.The proposed project will, for the first time, explore a purely pseudocapacitive material for capacitive deionization, namely MXene. Pseudocapacitance is distinguished by a capacitor-like electric response (linear charge-vs.-voltage), while charge storage is accomplished by a Faradaic process (ion intercalation). MXenes are a novel class of two-dimensional metal carbides, carbonitrides, and nitrides, first described in 2011. They are derived by chemical treatment of MAX phases, which are ternary metal carbides, carbonitrides, and nitrides - a large family of nanolamellar materials with over 60 members. Chemical etching by HF selectively removes atoms from the A-layer in MAX, leaving only M and X atoms left in the structure. Without the interlayer A-atoms, the three-dimensional MAX structure is transferred to two-dimensional nanolamellar MXene.The requested funding for one PhD student position will combine the two core topics of material science and aqueous electrochemical application. The PhD student will optimize the synthesis of V2C MXene from the MAX phase V2AlC and chemically modify its surface functionalities (oxidation / removal of surface functional groups etc.) by thermal methods. The impact of structure and surface chemistry on the electrochemical behavior of MXene (with / without modification) in aqueous media with NaCl as the salt will be explored. Besides CDI salt removal capacity and desalination rate, the longevity and structural changes during electrochemical cycling (including in situ methods) will be studied and a qualitative statement on the relations between MXene properties and CDI performance will be derived.

电容去离子（CDI）是一种新兴的技术，具有高效率和低能耗的优点，可用于从低摩尔浓度（低于100 mM）的水介质中去除离子。由于这一优点，CDI对于微咸水或工业水流的去离子特别有吸引力。CDI的过程类似于双层电容器（超级电容器）的操作：离子被电吸附到高度多孔的电极表面上，并有效地从给水流中去除。然后通过放电或电压反转来实现电极的再生。到目前为止，CDI领域的大部分工作都局限于纳米多孔碳的合成，分析和应用，考虑到高表面积和相对高的化学稳定性。随着对碳的关注，大多数工作已经探索了通过电化学双层固定离子的纯静电去离子。这就是为什么到目前为止，大多数碳作为电容材料已被应用于CDI。拟议的项目将首次探索用于电容去离子的纯赝电容材料，即MXene。赝电容通过类似电容器的电响应（线性电荷对线性电荷）来区分。电压），而电荷存储通过法拉第过程（离子嵌入）完成。MXenes是一类新型的二维金属碳化物、碳氮化物和氮化物，于2011年首次描述。它们是由MAX相的化学处理衍生的，MAX相是三元金属碳化物、碳氮化物和氮化物-一个拥有60多个成员的纳米层材料大家族。通过HF的化学蚀刻选择性地从MAX中的A层去除原子，仅在结构中留下M和X原子。在没有层间A原子的情况下，三维MAX结构被转移到二维纳米层MXene。一个博士生职位的申请资金将联合收割机结合材料科学和水电化学应用两个核心课题。博士生将优化从MAX相V2 AlC合成V2 C MXene，并对其表面功能进行化学修饰（氧化/去除表面官能团等）。通过热方法。将探索结构和表面化学对MXene（改性/未改性）在以NaCl为盐的水性介质中的电化学行为的影响。除了CDI盐去除能力和脱盐率之外，还将研究电化学循环（包括原位方法）过程中的寿命和结构变化，并将得出关于MXene性能与CDI性能之间关系的定性陈述。