Remote-Contact\nCatalysis for Target-Diameter Semiconducting\nCarbon Nanotube Arrays

Electrostatic\ncatalysis uses an external electric field (EEF) to\nrearrange the charge distribution to boost reaction rates and selectively\nproduce certain reaction products in small-molecule reactions (e.g.,\nDiels–Alder addition), requiring a 10 MV/cm field aligned with\nthe reaction axis. Such a large and oriented EEF is challenging for\nlarge-scale implementation or material growth with multiple reaction\naxes or steps. Here, we demonstrate that the energy band at the tip\nof an individual single-walled carbon nanotube (SWCNT) can be spontaneously\nshifted in a high-permittivity growth environment, with its other\nend in contact with a low-work-function electrode (e.g., hafnium carbide).\nBy adjusting the Fermi level at a point where there is a substantial\ndisparity in the density of states (DOS) between semiconducting (s-)\nand metallic (m-) SWCNTs, we achieve effective electrostatic catalysis\nfor 99.92% purity s-SWCNT growth with a narrow diameter distribution\n(0.95 ± 0.04 nm), targeting the requirement of advanced SWCNT-based\nelectronics for future computing.