Proposed Project I: Ion/Molecule Transport in sub-2 nm Nanochannels
Protein ion channels have exhibited various unique transport characteristics, such as selective K+ transport and ultra high proton mobility. Understanding and realizing these transport properties in artificial nanostructures could yield significant progress in energy conversion/storage and water desalination. Currently, 2-D confined sub-2nm nanotubes are the closest candidates to mimic the function of protein ion channels. These nanotubes can be fabricated based on SWCNT or using e-beam lithography coupled with atomic layer deposition technique. We propose to experimentally study ion/molecule transport in such nanotubes in the following three aspects: enhanced ion transport, selective Li+ transport and selective and fast water transport.
Proposed Project II: Nanostructured Materials for Energy Conversion and Storage
Batteries have been widely used in portable electronic devices, urgent power supply and vehicle starting-lighting-ignition. Recent increasing concerns on energy and environment further expand their applications in renewable energy storage and electric vehicles. Although the theoretical energy density of current batteries is high enough to satisfy these new demands, their practical energy density (which is around 30% percent of the theoretical energy density) is generally too low for such new applications due to the usage of inactive components (e.g. cover and separator ) and internal energy loss. To improve practical energy density, one needs to either develop new batteries with higher theoretical energy density or optimize the structure of current batteries. It has been shown that controlled nanostructures have potential applications on both aspects. We propose to design and synthesize new controlled nanostructures for two separate projects: new light nanostructured materials as current collectors and separators and new air cathode for Lithium-Air batteries.
Proposed Project III: Patterned Micro/Nano Structures for Phase Change Heat Transfer
About 40% of the total power generated in the US by heat engines is through the Rankine cycle, where water vapor is used to drive steam turbines. Boiling heat transfer plays an important role in these energy conversion devices since the critical heat flux (CHF) in the pool boiling curve limits the power density and efficiency. Although enhancing the CHF has great impact on many energy conversion and utilization systems, significant progress has remained elusive due to the complex mechanism of boiling heat transfer. It is generally believed that the far field limit (hydrodynamic limit) determines the CHF, but recent studies based on certain nanostructured surfaces also showed that surface related near-field limits (nucleation site density, surface wettability and capillary force) could enhance CHF. We propose to use a patterned micro/nano structure to systematically study and improve boiling heat transfer. Such a patterned micro/nano structure considers both far-field and near field limits. It can also be used in evaporation heat transfer to improve the heat transfer coefficient.
Proposed Project IV: Nanofluidic Devices for Biomedical Applications
One of the most important application areas of Nanofludics is bio-medicine. Since its length scale (~1-100 nm) is not only comparable with single biomolecule but also compatible with the range of several intermolecular forces, nanofluidics has been found lots of applications in genomics/proteomics, drug discovery, cancer diagnostics etc. Most of these new applications take the advantage of enhanced electrostatic interaction and steric interaction at the nanoscale. There have been few applications based on anomalous transport phenomena caused by enhanced van der Waals force/hydration force, surface interaction and surface-energy. We plan to develop new nanofluidic devices that harness these features for the following three applications: single ion/molecule detection, continuous protein separation and focusing; highly sensitive abel-free enzyme assay.