  Electrostatic catalysis has been an exciting development in chemical
synthesis (beyond enzymes catalysis) in recent years, boosting reaction rates
and selectively producing certain reaction products. Most of the studies to
date have been focused on using external electric field (EEF) to rearrange the
charge distribution in small molecule reactions such as Diels-Alder addition,
carbene reaction, etc. However, in order for these EEFs to be effective, a
field on the order of 1 V/nm (10 MV/cm) is required, and the direction of the
EEF has to be aligned with the reaction axis. Such a large and oriented EEF
will be challenging for large-scale implementation, or materials growth with
multiple reaction axis or steps. Here, we demonstrate that the energy band at
the tip of an individual single-walled carbon nanotube (SWCNT) can be
spontaneously shifted in a high-permittivity growth environment, with its other
end in contact with a low-work function electrode (e.g., hafnium carbide or
titanium carbide). By adjusting the Fermi level at a point where there is a
substantial disparity in the density of states (DOS) between semiconducting
(s-) and metallic (m-) SWCNTs, we achieve effective electrostatic catalysis for
s-SWCNT growth assisted by a weak EEF perturbation (200V/cm). This approach
enables the production of high-purity (99.92%) s-SWCNT horizontal arrays with
narrow diameter distribution (0.95+-0.04 nm), targeting the requirement of
advanced SWCNT-based electronics for future computing. These findings highlight
the potential of electrostatic catalysis in precise materials growth,
especially for s-SWCNTs, and pave the way for the development of advanced
SWCNT-based electronics.
