We discuss the FC-CVD synthesis of SWNTs, especially the tuning of tube atomic structure i.e. (n,m) distributions and subsequently the thin film color. By introducing various amount of CO₂ with CO as the carbon source and in-situ ferrocene decomposition generated Fe catalyst nanoparticles, we directly produced SWNT films with tunable (n,m) i.e. helicity distribution as well as tunable colors. When operating the FC-CVD reactor at the ambient pressure and at 850 ^oC temperature with 0.25 and 0.37 volume percent of added CO₂, the SWNT films display green and brown colors, respectively. We ascribed various colors to suitable diameter and narrow (n,m) distributions, which were determined in detail using the electron diffraction. We calculate the color maps for all SWNT (n,m) structures.

N. Wei et al. Adv. Mater. 2021, 33, 2006395.