Souped-Up Nanomotors

Drop a bimetal nanowire, composed of a segment of gold and a segment of platinum, into a solution of aqueous hydrogen peroxide and the tiny rod will chug along at about 8 μm/second. These catalytic nanomotors propel themselves because the platinum segment catalyzes the decomposition of hydrogen peroxide; the resulting oxygen provides thrust to drive the nanowire through the solution. By incorporating carbon nanotubes into the platinum end of the nanowires, Joseph Wang, Rawiwan Laocharoensuk, and Jared Burdick of Arizona State University have managed to get a nanomotor to zip around at about 50 μm/second, a speed that approaches that of biomolecular motors, such as kinesin (ACS Nano, DOI: 10.1021/nn800154g). According to the researchers, the nanotubes enhance the decomposition reaction, generating more oxygen and, consequently, providing a speed boost. Adding hydrazine to the hydrogen peroxide gives the nanomotors even more oomph, making them zoom along at 200 μm/second in some cases. "We expect that the development of highly efficient and controllable nanomotors will open the door to powerful nanovehicle systems performing diverse operations of increasing complexity," the researchers write.