CAREER: Exploring Fast Mass Transport in Carbon Nanofluidics

CBET -1653767 PI：Duan，Chuanhua最近的实验表明，与通过具有类似或更大尺寸但其他类型表面的通道的流动相比，通过具有纳米尺寸和光滑碳表面的通道的流动显著增强。然而，这些纳米通道中的流动增强机制尚未完全理解，部分原因是先前的实验产生了高度可变的结果。该奖项将支持一系列实验，以帮助调和先前实验中的模糊性，更重要的是，帮助揭示纳米尺度下流动增强的潜在机制。与之前大多数使用薄膜中纳米通道阵列的实验不同，该项目将测量通过单个纳米流体管道的水和离子的流量。一种新的纳米通道设计和制造方法，再加上毛细流动，将被用来直接测量的水力阻力，离子电导和流动性，以及水和离子流增强在单一的，明确的碳纳米管和石墨烯纳米通道。流动增强和材料性能之间的相关性，由计算模型的支持，将阐明关键因素，使通过碳纳米流体管道独特的流动。这些结果将有助于设计和制造碳纳米流体设备和结构，用于各种应用，包括水淡化，电池和燃料电池，芯片实验室，以及解释地质学，生物学和生理学中的某些流动。该奖项包括对各级学生教育活动的支持。卡通动画和动手实验室工具包，说明了独特的物理流动在纳米级将开发使用的K-12学生。该项目将为本科生，特别是来自代表性不足群体的本科生提供参与研究的机会。由于使用由多导管碳纳米管或石墨烯纳米通道组成的膜的研究由于纳米尺寸的多分散性而引入了模糊性，因此该奖项将研究具有明确尺寸，表面性质和屏障材料的单个碳纳米管和石墨烯纳米通道中的水和离子传输。实验将测试的假设，即快速的质量传输的水和离子在这些通道中的结果从独特的表面水和表面离子的相互作用，这在很大程度上取决于基板或屏障材料，以及对这些碳纳米流体管道的限制和表面特性。实验测量将与分子动力学模拟，考虑明确的基板/屏障材料，表面电荷和离子-水相互作用的影响进行比较。该项目中制造的碳纳米流体器件也将为研究人员提供一个研究选择性离子和气体传输的平台，这不仅可以提高对碳纳米流体的理解，而且可以扩展其在化学和生物分离过程中的实际应用。

CBET - 1653767PI: Duan, ChuanhuaRecent experiments indicate that flow through channels that have nanometer dimensions and smooth carbon surfaces is significantly enhanced compared with flow through channels that have similar or larger dimensions but other types of surfaces. However, the mechanism of flow enhancement in these nanochannels is not fully understood, in part because prior experiments produced highly variable results. This award will support a series of experiments to help reconcile ambiguities in prior experiments and, more importantly, to help uncover the underlying mechanisms of flow enhancement at nanoscale dimensions. Unlike most prior experiments that used flow through arrays of nanochannels in a thin membrane, this project will measure flow of water and ions through individual nanofluidic conduits. A new method of nanochannel design and fabrication, coupled with capillary flow, will be used to directly measure the hydraulic resistance, ionic conductance and mobility, as well as water and ion flow enhancement in single, well-defined carbon nanotubes and graphene nanochannels. Correlations between flow enhancement and material properties, supported by computational modeling, will elucidate key factors that make flow through carbon nanofluidic conduits unique. The results will be useful in designing and fabricating carbon nanofluidic devices and structures for a variety of applications, including water desalination, batteries and fuel cells, lab-on-a-chip, as well as in interpreting certain flows in geology, biology and physiology. The award includes support for educational activities for students at all academic levels. Cartoon animations and hands-on lab kits that illustrate the unique physics of flow at the nanoscale will be developed for use by K-12 students. The project will provide opportunities for undergraduates, especially those from underrepresented groups, to participate in the research. Since research using membranes consisting of multi-conduit carbon nanotubes or graphene nanochannels introduces ambiguities due to conduit-size polydispersity, this award will study water and ion transport in single carbon nanotubes and graphene nanochannels with well-defined sizes, surface properties and barrier materials. The experiments will test the hypothesis that fast mass transport of water and ions in these channels results from unique surface-water and surface-ion interactions, which strongly depend on the substrate or barrier material as well as on the confinement and surface properties of these carbon nanofluidic conduits. Experimental measurements will be compared with molecular dynamics simulations that consider explicitly effects of substrate/barrier material, surface charge, and ion-water interactions. The carbon nanofluidic devices fabricated in this project will also provide investigators a platform to study selective ion and gas transport, which could not only improve understanding of carbon nanofluidics, but also expand its practical applications to chemical and biological separations processes.