CAREER: Rational Synthesis and Studies of Functionalized Carbon Nanotubes

Stanislaus S. Wong, SUNY at Stony Brook, DMR-0348239Developing near-edge X-ray absorption

fine structure spectroscopy (NEXAFS) is critical to characterizing nanoscale

systems.

(a). NEXAFS can simultaneously track both the nature of carbon nanotube

electronic structure and the chemical functional groups introduced.

Specifically, alterations in the π* and σ* transitions, indicative of extensive

sidewall functionalization, can gauge the level of oxidation and of structural modification made to these nanotubes.

(b). Solution-phase ozonolysis of multiwalled nanotubes (MWNTs) leads

to their opening of end caps and functionalization of dangling bonds

with oxygenated functional groups as

well as to their purification.

a

b

We have developed an ozonolysis protocol that purifies carbon nanotubes by removing amorphous carbon and metal impurities. In addition, ozonolysis provides a new means for generalizing traditional chemistry to nanotube sidewalls, defect sites, and surfaces. We have recently begun developing a synchrotron-based technique (NEXAFS) as a means of characterizing nanoscale samples, such as carbon nanotubes and boron nitride nanotubes.

(a). NEXAFS spectroscopy is a technique that involves the excitation of electrons from a core level to partially filled and empty states. It is an important element-specific characterization tool capable of obtaining electronic, structural, and bonding information, not only about nanotube carbons but also about those associated with surface functionalities, that are introduced by oxidative processes. We have found that NEXAFS spectroscopy can simultaneously track both the nature of the nanotube electronic structure and the chemical functional groups introduced. Specifically, the appearance of π* and σ* transitions, corresponding to C=O and C-O oxygenated groups respectively, as well as the attenuation of the ring π* transition, indicative of extensive sidewall functionalization, can be used to gauge the level of oxidation and of structural modification made to these nanotubes. Ref.: Sarbajit Banerjee†, Tirandai Hemraj-Benny†, Mahalingam Balasubramanian, Daniel A. Fischer, James A. Misewich, and Stanislaus S. Wong, Chem. Commun., (7), 772-773 (2004).

(b). We have presented a systematic study of the chemical and electronic structure as well as the purity of ozonized multiwallec carbon nanotubes (MWNTs). These tubes have been structurally characterized by transmission electron microscopy (TEM). This study demonstrates the use of Raman, infrared, and NEXAFS spectroscopies to comprehensively determine the presence and distribution of oxygenated moieties on these ozonized nanotubes.Ref.: Sarbajit Banerjee, Tirandai Hemraj-Benny, Mahalingam Balasubramanian, Daniel A. Fischer, James A. Misewich, and Stanislaus S. Wong, ChemPhysChem, 5, 1416-1422 (2004)

CAREER: Rational Synthesis and Studies of Functionalized Carbon Nanotubes

Stanislaus S. Wong, SUNY at Stony Brook, DMR-0348239

Education:- Two undergraduates (V. Masson and J. Dargan) and five graduate students (T. Hemraj-Benny, Y. Mao, H. Zhou, F. Zhang, and T-J. Park) contributed substantially to this work. S. Banerjee (Ph.D. ‘04) also was a key player in all of the projects.

- Masson was a summer student, supported by NSF.

- Mao obtained a Sigma Xi Grant-in-Aid of Research in 2004 and Travel Award in 2005.

- Park received a Sigma Xi Travel Award and an American Chemical Society Division of Inorganic Chemistry Travel Award in 2005.

Outreach:- Hosted Stephen Mui (below, right) on a DOE Summer Undergraduate Laboratory Internship (SULI). In his project, he used NSF-funded facilities. - Primary organizer of Brookhaven National Lab Open House for incoming 1st year Chemistry departmental graduate students. Tours of the Chemistry and Materials Sciences Departments as well as the National Synchrotron Light Source.

CAREER: Rational Synthesis and Studies of Functionalized Carbon Nanotubes

Stanislaus S. Wong, SUNY at Stony Brook, DMR-0348239

Two undergraduates (Vicki Masson and J. Dargan) and six graduate students (Sarbajit Banerjee, Tirandai Hemraj, Yuanbing Mao, Tae Jin Park, Hongjun Zhou, and Fen Zhang) contributed to the work presented. Banerjee was the key player in all of the experiments. Hemraj-Benny and Park participated in NEXAFS and NMR experiments, respectively. Dargan performed large scale chemical functionalization procedures, associated with optimizing ozonolysis conditions. He was involved in spectroscopic analyses of samples. Mao, Zhou, Zhang, and Park also worked on an off-shoot of these efforts towards understanding the chemistry and physics of non-carbon nanomaterials.

One of the PI’s outreach initiatives was to generate added intellectual exposure to BNL facilities for graduate and undergraduate students. The PI hosted Stephen Mui (undergraduate from Columbia University) on a Department of Energy Summer Undergraduate Laboratory Internship to perform research using various instrumentation and facilities at Brookhaven National Laboratory. The PI also organized a tour for first-year Chemistry graduate students in which they visited a range of facilities, including the NSLS beam lines, the Positron Emission Tomography Facility, a host of spectroscopy and magnetic resonance imaging labs in the Chemistry Department, and an AFM lab in the Materials Science Department, many of which they ended up utilizing during their subsequent research.

CAREER: Rational Synthesis and Studies of Functionalized Carbon Nanotubes

Stanislaus S. Wong, SUNY at Stony Brook, DMR-0348239