“…Hence, for large-scale CNTs production, the role of the catalyst is one of the major factors, while for this, only expensive transition metals such as Ni, Fe, Pt, V, Mo, Co, Y, and La are being actively used [57][58][59]. For example, in the case of CNTs in ancient items, the catalyst iron (Fe) might have originated from the soil, and then it could have favored the growth of CNTs upon heating the pottery at high temperatures [2]. Any go-ahead factor that reduced the cost of CNTs on a large scale will help in the CNTs applications for the end-user.…”