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

Abstract

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.