Controlling the Diffusive Motion of Fullerene-Wheeled Nanocars Utilizing a Hybrid Substrate

In the previous years,
a few types of nanocars have been built
with the promising potential to transport other molecules, to provide
bottom-up assembly, or to perform other mechanical tasks. In this
study, we propose a method to convert the diffusive displacement of
nanocars to a guided motion in a desired path by adding some impurity
atoms in the substrate. We investigated the motion of C60 as well as the nanotruck and the nanocar on a flat gold substrate
containing silver contamination and conversely a silver substrate
containing gold contamination at the different temperatures. The results
showed that silver impurity on the gold substrate act as a repellent
obstacle in the path of C60 making it unable to enter the
silver region even at high temperatures, although at 600 K and higher
temperatures, it was finally able to enter the silver segment. Nevertheless,
a big enough silver impurity proved to be an impenetrable barrier
for the nanocar and the nanotruck even at 600 K. The study of motion
on the silver substrate containing gold impurity revealed that despite
the fact that C60 had a longer range motion on the pure
silver surface than on the pure gold one, it preferred to move around
on the small gold impurity rather than the silver surface. Although
C60 was able to escape from the gold impurity at a temperature
of 400 K or higher, at a temperature of 300 K or less, the C60 was completely confined by the gold impurity boundary. Even when
the C60 managed to escape from one gold segment at high
temperatures, it quickly became entrapped in another gold zone. Finally,
we study the motion on a specially designed striped gold–silver
substrate at different temperatures. We found that the striped substrate
completely confined the motion of the nanocar and the nanotruck, even
at 600 K. Although C60 was able to leave the gold lane
at temperatures of 300 K or higher, most of the time, it moves on
the gold path. We predict that a combination of many other pairs of
face-centered cubic metals could be employed to synthesize a similar
pathway. In addition, the presence of impurity in the substrate severely
restricts the motion range of nanocars or other molecular machines
by acting either as a repellent obstacle or a snatching trap.