Research Terms
Energy Solar Energy Composite Materials Materials Synthesis Colloid Chemistry Surface Chemistry Photovoltaics
Industries
Advanced Materials & Products Solar
Nanoscale Science and Engineering Forum of AIChE, Chairperson; 2013 - present
Electrochemical Society (ECS), Member; 2008 - present
Nanoscale Science and Engineering Forum of AIChE, Board of Directors; 2007 - 2012
American Society for Engineering Education (ASEE), Member; 2006 - present
American Chemical Society (ACS), Member; 2004 - present
Materials Research Society (MRS) , Member; 2003 - present
American Institute of Chemical Engineers (AIChE), Member; 1995 - present
Center for Surface Science and Engineering
Director |
Kirk Ziegler |
Phone | (352) 392-3412 |
Website | http://csse.che.ufl.edu/ |
Mission | 1) Enhance the knowledge on interfaces and utilize this knowledge for the benefit of the world through innovative technological applications; 2) educate scientists and engineers with a better understanding of fundamental aspects of molecular and macroscopic phenomena occurring at interfaces; and 3) collaborate with industries for technological advances using surface science and engineering knowledge and provide the state of the art short courses and symposia for upgrading scientific knowledge of R&D staff of industry. |
This Anodized Alumina template (AAO) constructs ordered Particle-In-Cavity (PIC) nanostructures that are thermally stable and high in nanocavity density. These nanostructures may be employed large-scale in fields such as nanoplasmonics, photochemical catalysts, batteries, photovoltaics, and biological sensors. The annual global revenue for photovoltaics alone is projected to grow to over $78 billion by 2017. Current fabrication methods of nanocavity and Particle-In-Cavity (PIC) nanostructures use inconsistent transfer processes and yield nanoparticles prone to Ostwald ripening at high temperatures, resulting in ineffective PIC nanosystems. Additionally, existing processes generally require harsh, toxic chemicals and therefore must be handled by researchers and manufacturers with great caution. Researchers at the University of Florida have created a systematic and cost-effective fabrication method for PIC nanostructures that eliminates the nanopore-related inconsistencies of existing nanostructures in addition to improving the safety, simplicity, and efficacy of the nanostructure fabrication process.
AAO template coupled with nanoparticle insertion produces highly ordered PIC nanostructures for large-area applications
This nanostructure fabrication using anodized alumina templates introduces a simple yet inexpensive and versatile technique for creating large-area nanoparticle assembly, nanocavity and particle-in-cavity nanostructures that have tunable dimensions below 100 nm with perfect hexagonal ordering on various substrates. The resulting nanostructure is extremely thermally stable and maintains the same density even after high temperature processing. Since the nanowires are embedded in the conductive interlayer, the particle-in-cavity nanostructure provides much better electrical contact for nanowire-based devices. The nonlithographic nanopatterning uses anodized alumina as a mask to produce structures with perfect ordering on various substrates. The technology also opens up more opportunities for high temperature applications that are hindered by Ostwald ripening for conventional nano-devices.
These anodized alumina nanowires are vertically aligned, feature ultra-high density and are easily deposited into templates through a variety of existing methods. They are transferable onto flexible substrates, offering an inexpensive way of manufacturing flexible nanowires. Integrating nanowires onto flexible devices to enhance efficiency has gained considerable research interest in recent years. The wearable device and flexible electronics market is worth over $8 billion. Current technologies are limited by the inability to manufacture efficient, cost-effective flexible devices. University of Florida researchers are able to produce flexible nanowires by using anodized alumina, resulting in nanowires with high density and vertically aligned morphology with perfect ordering. These nanowires can also be used in electronics, such as photovoltaics and sensors.
Production of flexible nanowires for wearable electronics, flexible displays, and energy conversion devices.
The anodized alumina acts as an ultra-high density, nanoporous template to produce flexible, inexpensive nanowires. The pore size, density, pore ordering, and inter-pore distance can be changed by altering the types and concentration of electrolytes, temperature, or anodization voltage in the template. The nanowires are synthesized by depositing material into the vertical pores of the template. The diameter of the nanowires is tunable on the nanometer scale while the length of the nanowires is dependent upon the template thickness, deposition conditions and deposition time. The template is then removed using a solvent. A thin film of conductive interlayer material may be deposited onto the nanowires to reduce contact resistance between the nanowire and electrode interface. The technology is extremely versatile; the deposition method, metals, semiconductors, and polymers used in processing these nanowires can be altered to achieve the desired results.
This cryogenic heat transfer surface made of aluminum and an anodized aluminum oxide layer is capable of substantial heat transfer enhancement in all three boiling and quenching regimes. The surface layer features nanoscopic pores that effectively trap moisture to grant it substantial heat transfer enhancements. These enhancements can be applied effectively to a variety of engineering applications including power production, advance electronics, and cryogenic fluid systems. Cryogenic fluids are widely used in industrial applications, space explorations, and cryosurgery devices, and systems that use them require a "chilldown" process to adjust the system to low operating temperatures. Power production devices and advanced electronic systems rely on efficient heat transfer mechanisms to maintain an optimal temperature level to maximize power density for higher system efficiency. But as conventional convective heat transfer technologies reach their limits, researchers are looking for modern phase-change thermal energy transport mechanisms for solutions. Researchers at the University of Florida have developed a solution with this surface layer of anodized aluminum oxide nanopores that significantly enhances heat transfer.
Nanoporous aluminum oxide surface that enhances heat transfer efficiency to improve various industrial systems
The anodized aluminum oxide nanoporous texture of the surface layer creates a highly wettable and superhydrophilic property that drastically alters boiling and quenching properties. The pores are created by first electrically increasing the thickness of aluminum substrate, then using acid to create a pattern of nanopores on the aluminum surface. The nanoporous alumina substrates can be modified to have different pore sizes, distribution, and morphologies that in turn affect the heat exchange properties. For cryogenic applications, the nanoporous surface can shorten the chilldown time up to 20 percent, which can reduce cryogenic fluid consumption by nearly 30 percent and increase safely with reduced boil-off and venting points. This surface also significantly increases the Leidenfrost point, maintaining a higher level of heat transfer in a larger range of surface temperature.