We describe an efficient, bubble-free nanoscale motor consisting of a copper-platinum (Cu-Pt) segmented rod that operates as a nanobattery in dilute aqueous Br(2) or I(2) solutions. The motion of the rod is powered by self-electrophoresis caused by redox reactions occurring on the two different metal segments. Asymmetric ratchet-shaped pure copper nanorods were also found to rotate and tumble in aqueous Br(2) solution because of the ion gradient arising from asymmetric dissolution of copper.