Data-driven understanding of collective carbon nanotube growth by in situ characterization and nanoscale metrology

Mostafa Bedewy

doi:10.1557/jmr.2016.498

Abstract

Aligned carbon nanotubes (CNTs) possess great potential for transforming the fabrication of advanced interfacial materials for energy and mass transport as well as for structural composites. Realizing this potential, however, requires building a deeper understanding and exercising greater control on the atomic scale physicochemical processes underlying the bottom-up synthesis and self-organization of CNTs. Hence, in situ nanoscale metrology and characterization techniques were developed for interrogating CNTs as they grow, interact, and self-assemble. This article presents an overview of recent research on characterization of CNT growth by chemical vapor deposition (CVD), organized into three categories based on the growth stage, for which each technique provides information: (I) catalyst preparation and treatment, (II) catalytic activation and CNT nucleation, and (III) CNT growth and termination. Combining all three categories together provides insights into building the process–structure relationship, and paves the way for producing tailored CNT structures having desired properties for target applications.

Highlights

Aligned carbon nanotubes (CNT), referred to as CNT forests, have repeatedly been shown to possess great potential for transforming the fabrication of thermal interfaces, electrical interconnects, nanoporous membranes, and structural fibers/composites.[1,2] realizing this potential has proven to be challenging
Bedewy: Data-driven understanding of collective carbon nanotube growth by in situ characterization and nanoscale metrology alignment, and density, as shown schematically in Fig. 1.5–8 These variations arise from the dynamics of growth, which are dominated by time-varying kinetics of chemical decomposition, catalytic activation, catalyst poisoning/deactivation, and atomic diffusion.[9,10,11,12,13,14,15,16]
This review focuses on chemical vapor deposition (CVD) growth of CNTs using acetylene and ethylene feedstock, and does not focus on the chemistry of growth enhancers

Summary

INTRODUCTION

Aligned carbon nanotubes (CNT), referred to as CNT forests, have repeatedly been shown to possess great potential for transforming the fabrication of thermal interfaces, electrical interconnects, nanoporous membranes, and structural fibers/composites.[1,2] realizing this potential has proven to be challenging. M. Bedewy: Data-driven understanding of collective carbon nanotube growth by in situ characterization and nanoscale metrology alignment, and density, as shown schematically in Fig. 1.5–8 These variations arise from the dynamics of growth, which are dominated by time-varying kinetics of chemical decomposition, catalytic activation, catalyst poisoning/deactivation, and atomic diffusion.[9,10,11,12,13,14,15,16] Importantly, the non-uniform morphology of CNT forests influences their properties, such as in mechanical compression for example, which was shown to be affected by density gradients.[17] revealing the process–structure and structure–property relationships requires a comprehensive understanding of the atomic scale physicochemical processes underlying the bottom-up synthesis and selforganization of aligned CNTs. To that end, a large number of in situ nanoscale metrology and characterization techniques were explored over the past two decades for interrogating a large number of individual CNTs simultaneously as they grow, interact with each other, and self-assemble into the aligned morphology.

CATALYST PREPARATION AND TREATMENT

CNT GROWTH AND TERMINATION

OUTLOOK ON REMAINING CHALLENGES

CONCLUSIONS