Impact of residence time on bundle length distribution of carbon nanotubes in floating-catalyst chemical vapor deposition synthesis

The synthesis of long carbon nanotubes (CNTs) is crucial for translating their exceptional nanoscale properties to macroscopic applications. In this study, we report the impact of residence time on the bundle length of CNTs synthesized using a floating-catalyst chemical vapor deposition process. We analyzed the bundle length distribution of CNTs with the Schulz-Flory model, and found that CNT length increases with residence time up to a critical synthesis temperature. However, above this temperature, CNTs rapidly elongate, with the growth eventually plateauing. Further optimization of the carbon-to-catalytic iron molar ratio can enhance the bundle length.