Aligned Carbon Nanotubes as Porous Materials for Selective Gas Adsorption and Desorption

我们在第三资助期的努力将继续致力于对高度有序的碳纳米管（CNTs）阵列中气体的吸附有深入的了解。技术上的激励因素是这种阵列有潜力作为烟道气中有害成分的吸附剂，如二氧化碳、二氧化硫、氮氧化物和硫化氢，即用于气体净化。然而，在基础科学水平上，碳纳米管阵列也是研究碳材料中气体吸附的完美模型系统。我们可以在控制良好的几何参数（管径，管间距离，长度）的情况下重复制造它们，这使它们成为与理论模拟研究比较的理想选择。基于第一和第二资助期的成果，我们将继续使用实验技术（目标制备、光谱表征和环境和高压下的特定吸附测量）与理论方法（吸附热力学的大规范蒙特卡罗模拟、传输过程的分子动力学和分析模型）相结合，在分子水平上获得吸附机制的统一图像。科学问题的范围和使用的方法将会扩大。我们在资助第三期的研究重点将是：混合物的吸附。这包括从分离和净化过程的角度解释某些组分的吸附选择性，以及对多种气体吸附中的正、负相互干扰的理解。作为本副标题的一部分，我们还将研究一种成分为水的混合物，因为湿度在技术应用中无处不在。带电纳米管阵列。我们的理论研究预测二氧化碳的吸附可以通过放置在碳纳米管阵列上的电荷来调节。现在，我们将尝试在实验装置中验证这些预测，以测量电荷可以外部控制的电接触碳纳米管阵列的气体吸附性。同时，还将对其他气体进行进一步的模拟。我们还将研究使用碳纳米管阵列的电接触块作为静电摆动吸附/解吸装置的可能性。化学修饰的CNTs。我们已经证明等离子体处理和高温CO2处理能够对碳纳米管表面进行化学修饰，有时会导致气体吸附量急剧增加。这些研究将继续进行，并伴随着现实的模拟，目的是获得对单个表面基团和缺陷的吸附能力、它们的相互作用和它们的选择性的分子理解。这些共同努力的结果将用于建议目标表面功能化与定制的吸附和选择性概况。

Summary Our efforts during funding period three will continue to be aimed at gaining a solid understanding of the adsorption of gases in highly ordered arrays of carbon nanotubes (CNTs). The technological incentive is the potential of such arrays as adsorbents for noxious components of flue gases, such as CO2, SO2, NOx and H2S, i.e. for gas purification. On a fundamental scientific level, however, CNT arrays are also perfect model systems for the investigation of gas adsorption in carbon materials. We can manufacture them reproducibly with well-controlled geometry parameters (tube diameter, intertube distance, length), which makes them ideal for comparison with theoretical simulation studies. Building on our results from funding periods 1 and 2, we will continue to use experimental techniques (targeted preparation, spectroscopic characterization and specific adsorption measurements under ambient and high pressure) in tandem with theoretical methods (grand-canonical Monte Carlo simulations of adsorption thermodynamics, molecular dynamics for transport processes, and analytical models) to obtain a unified picture of the adsorption mechanisms at the molecular level. The range of scientific questions and the methods to be used will be expanded. The specific foci of our research in funding period three will be on: Adsorption of mixtures. This includes the explanation of adsorption selectivities for certain components with a view to separation and purification processes, as well as an understanding of positive and negative mutual interference in the adsorption of multiple gases. As part of this subtopic, we will also investigate mixtures with one component being water, as humidity is omnipresent in technical applications. Charged nanotube arrays. Our theoretical studies have predicted that the adsorption of CO2 can be modulated by electrical charges placed on the CNT arrays. We will now try and verify these predictions in an experimental set-up to measure gas adsorptivity of electrically contacted CNT arrays whose charge can be externally controlled. Simultaneously, further simulations for other gases will be performed. We will also investigate the possibility of using electrically contacted blocks of CNT arrays as electrostatic swing adsorption/desorption devices. Chemically modified CNTs. We have shown that plasma treatment and high-temperature CO2 treatment are able to chemically modify the CNT surfaces, sometimes leading to drastically increased gas adsorption. These studies will be continued and accompanied by realistic simulations with the aim of obtaining a molecular understanding of the adsorption capability of individual surface groups and defects, their mutual interaction and their selectivity. The results of these combined efforts will be used to suggest target surface functionalisations with tailored adsorption and selectivity profiles.