Catalyst design for (n,m)-targeted carbon nanotube syntheses

William Marsh Rice University, Houston TX

Investigators

Abstract

Carbon nanotubes (CNTs) have failed to fulfill long-held expectations of high-surface-area coupled with outstanding electronic properties. This owes primarily to an inability to catalytically synthesize the nanotubes as single-walled entities in a patterned "chiral" (n,m)-structure; and is despite theoretical arguments by the principal investigator that such structures should be possible if the proper combination of catalyst, support and chemical vapor deposition conditions can be achieved. Recently, experimental success in producing such chiral CNTs has been demonstrated. The project will draw upon the experimental achievement to develop refined and expanded theoretical predictions that should guide further developments of catalytic chemical vapor deposition (CCVD) toward optimal catalytic materials and processing conditions. The ability to produce single-wall carbon nanotubes of high purity at industrial scale could have profound effects on commercial applications of CNT technology, ideally with U.S. researchers leading the way. The project will evolve a critical recent breakthrough in the PI's group revealing that the origin of CNT chirality can be described by a set of guidelines that will aid design of catalysts for (n,m)-targeted CNT synthesis. The researchers now clearly recognize that this complex phenomenon lies at the intersection of two large and mature fields: heterogeneous catalysis and crystal growth. Bringing together these paradigms from chemistry and materials science is expected to result in a transformative theoretical framework that should enable finding ways to engineer chiral selective CNT production, thus advancing a variety of long-awaited applications, all pending availability of single (n,m) type material. This will be achieved by a comprehensive atomistic investigation of structure and energetics of various metal-nanoparticle catalysts combined with state-of-the-art quantitative analysis of the thermodynamics and kinetics of ruling processes at the catalyst-CNT interface. To enable a higher probability of significantly new understanding, hypotheses based on such microscopic results will be validated through a continuing comparison with experimental data in the literature and through contacts with several experimental labs. The cross-disciplinary nature of the project will provide educational opportunities to both graduate and undergraduate students in computational chemistry, molecular dynamics, and statistical physics. Research results will be organized in a curated public materials property database. The project will also involve outreach to Houston high school students through Rice University and close ties to the Houston Museum of Natural Sciences.