Highly ordered, electrically modulatable, conductive mesoporous separation layers

• Applicant: Professorin Dr. Annette Andrieu-Brunsen
• Subject Area: Fluid Mechanics ; Synthesis and Properties of Functional Materials
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 509491635

Modeling shows the potential of transient separation concepts to increase selectivity and to reduce energy consumption in membrane-based separation. In subproject A3, a specific configuration of the lead experiment "Electrically Modulatable Nanopores" will be established, investigating the possibility of experimentally improving separation performance by using conductive, continuously switching, structurally stable, asymmetric mesopores. Applying a continuously oscillating potential to a conductive and asymmetrically designed mesoporous layer is expected to continuously vary the mesopore wall charge and thus the ionic pore mass transport. This effect is expected to be further adjusted by using redox responsive pore wall chemistry. To date various studies on gated/ responsive (polymer) functionalized mesopores and their ionic transport gating exist. In most cases gating remains slow in the range of seconds to minutes. This is mainly due to the applied responsive polymers. Using conductive nanopores gating is expected to be sufficiently fast. A few studies on conductive indium tin oxide (ITO) mesoporous layers represent a promising route towards conductive nanopores. To realize continuous fast gating at the time scale of ionic mass transport and thus transient mass transport through conductive nanopores, the first objective will consist of fabrication and optimization of conductive mesoporous ITO layers and their functionalization with respect to porous structure, conductivity, and pore wall charge. As a second objective, transport properties in dependence of process parameters, such as the gating frequency, will be investigated. As a third objective we will identify possibilities and limits of such transient nanopores in the context of separation, especially considering medium sized molecules or small ions. Thereby, the first funding period explicitly does not focus on a separation problem but attempts to understand possibilities and limits of transient mesopores and to focus on material and process parameter (frequency) optimization. Based on these insights with respect to mechanistic understanding and separation potential, future funding periods aim to use the gained understanding and the achieved proof of concept to further develop a rational design of transient nanopore performance with respect to selectivity and energy consumption, including application relevant process parameters such as solution composition and ion mixtures as well as concentration. Based on the knowledge of the material characteristics and process parameter influence, mainly referring to the applied gating frequency, investigated within the first funding period, we aim for rational design criteria for transient pores.

• DFG Programme: Research Units
• Subproject of: FOR 5584: Transient Sieves