Enhancing Carbon Nanotube Growth in Large Scale Production: A Multifaceted Investigation of Key Factors in the CVD Process

Abstract

Electrification of transportation and personally owned vehicles has revitalized the need for enhanced power systems. Moreover, renewable energy systems' harvesting times and load peak times are sometimes incoherent. This necessitates large and efficient energy storage devices to compensate for the sudden increase in demand. Supercapacitors, known for their formidable power density, are ideal energy storage devices. They leverage the unprecedented surface area of carbon nanotubes (CNTs) as charge storage sites, making them highly effective for this purpose. Despite their potential, the growth of CNTs has faced numerous challenges since their discovery a few decades ago.

This project investigates two chemical vapor deposition (CVD) reactors, comparing them to enhance the parameters that promote CNTs growth. It examines the gas dynamics and concentrations within these reactors, as well as various gas compositions and their effects on CNT deposition. The performance of these gas compositions is analyzed, identifying areas for improvement. Through simulation, it was determined that halving the current gas flow improves temperature preservation and velocity. Experimentation confirmed these findings, achieving similar results and reducing gas consumption by half.

The study also explores suggestions for enhancing gas composition performance by adjusting the composition or modifying the underlying conditions. Novel designs and ideas for gas confinement, such as an aluminum frame, better gas mixing, and uniform gas composition using an internal fan, are analyzed. Another experiment, guided by simulation, achieved a significant CNT yield of 30 mg/cm², demonstrating effective atmospheric control and consistent carbon supply.

Finally, a separate project investigated replacing argon with nitrogen as a carrier gas. A control experiment revealed that nitrogen produced the same amount of CNTs as argon. However, the composition that yielded the highest CNT production was found to be 150:100:20 (N2:H2:C2H2).