Kirk J. Ziegler
Ph.D., 2001, University of Texas at Austin
Ph : 352-392-3412
421 CHE
Faculty Web Page
Single-walled carbon nanotube dispersion and separations
Nanowire and nanotube synthesis and applications
As technology rapidly shrinks toward the nanometer length-scale, understanding how dimensionality affects materials properties has become increasingly important. At the nanoscale, electron interactions are restricted resulting in unique properties that differ from the macroscopic world. Our goal is to synthesize nanomaterials exhibiting unique properties, understand and manipulate their properties, and integrate them into critical new devices and inventions that will affect microelectronics, manufacturing, healthcare, biotechnology, energy, and materials science.
Single-walled carbon nanotube dispersion and separations

Keywords : Nano-sciences, Materials/Devices, Surface Science, Transport Phenomena


Researchers have envisioned many applications for single-walled carbon nanotubes (SWCNTs) that take advantage of their astounding physical properties. SWCNTs are single atom thick sheets of graphene that are rolled into a seamless cylinder defined by the unit vectors (n,m). The different (n,m) vectors give rise to SWCNTs with specific properties governed by the crystalline structure. Theoretically, metallic SWCNTs should make up one third of all possible nanotubes while the rest are semiconducting SWCNTs with varying band gaps. Currently, all SWCNT synthetic approaches produce a variety of SWCNT (n,m) types that limit their use in many applications. Although considerable progress has been made in controlling the diameters and types of SWCNTs produced, a variety of post-synthesis separations are still required to produce nanotubes of specific length, diameter and electronic type.

It is becoming increasingly clear that SWCNT-surfactant and surfactant-surfactant interactions are important in defining dispersion, photoluminescence (PL) properties of SWCNTs, and their separation. Our group focuses on the role that the surfactant structure surrounding the nanotubes has on these processes and properties. Of particular interest over the last several years has been the development of a simple and scalable technique for the separation of SWCNTs. Of the various techniques capable of separating SWCNTs, selective adsorption on agarose or dextran gels is currently one of the most promising methods for large-scale, high-throughput separations. Our group has shown that the surfactant structure dictates both enthalpic and entropic effects that yield selective adsorption of SWCNTs. Our work aims to use this knowledge to develop a single-column, single-elution profile separation process that is capable of separating all (n,m) types within the mixture.

Nanowires and Nanotubes in Energy Applications
Keywords : Nano-sciences, Electrochemical, Energy, Materials/Devices, Surface Science

Nanowires are structures that have unique properties that make them advantageous for many energy storage and generation applications. For example, nanowires are easily integrated into device structures because they can maintain good electrical connections. This improves their charge transport within devices. These features have made nanowires or nanotubes attractive components of solar cells, batteries, fuel cells, thermoelectrics, and ultracapacitors.

Surface area is critical in many photovoltaic and charge storage applications since it either defines the amount of electrons that are transferred or the amount of charge stored. In the development of energy devices based on nanostructures, there has been a compromise between the electron transport and surface area. Typically, nanoparticles offer high surface area but poor charge transport because of the grain boundaries between particles. Traditionally, nanowires have good charge transport but very low surface area. Our group has been focusing on new methods to prepare nanowire arrays with ultrahigh surface areas that can take advantage of the enhanced electron transport.

Fabricating nanowire and nanotube devices with the dimensions and materials required to maximize surface area remains challenging. Although CVD is the most popular technique for growing nanowire arrays, it fails to provide the density of nanowires needed to achieve ultrahigh surface areas. Therefore, the use of templates, such as anodized aluminum oxide (AAO), remains a promising method to achieve the surface area required for many energy generation and storage applications.

Recent Publications
1. J.G. Clar, C.A. Silvera-Batista, S. Youn, J.-C. J. Bonzongo, and K.J. Ziegler. Interactive forces between SDS-suspended single-wall carbon nanotubes and agarose gels. J. Am. Chem. Soc., DOI: 10.1021/ja4052526.
2. S. Youn, R.K. Wang, J. Gao, A. Hovsepyan, K.J. Ziegler, J.-C. Bonzongo, and G. Bitton. Mitigation of the impact of single-walled carbon nanotubes on a freshwater green algae: Pseudokirchneriella subcapitata. Nanotoxicology, 2012, 6, 161.
3. J.J. Hill, N. Banks, K. Haller, M.E. Orazem, and K.J. Ziegler. An interfacial and bulk charge transport model for dye-sensitized solar cells based on photoanodes consisting of core-shell nanowire arrays. J. Am. Chem. Soc., 2011, 133, 18663.
4. C. Silvera-Batista, D. Scott, S. McLeod, and K.J. Ziegler. A mechanistic study of the selective retention of SDS-suspended single-wall carbon nanotubes on agarose gels. J. Phys. Chem. C, 2011, 115, 9361.
5. J.J. Hill, K. Haller, B. Gelfand, and K.J. Ziegler. Eliminating capillary coalescence of nanowire arrays with applied electric fields. ACS Appl. Mater. Inter. 2010, 2, 1992.