Disk-like nanojets with steerable trajectory using platinum nozzle nanoengines

Abstract

Self-propelled disk-like nanojets are proposed and illustrated, consisting of non-catalytic gold (Au), central magnetic nickel (Ni) and catalytic nozzle platinum (Pt). This innovative type of Au–Ni–Pt nanojet with either one off-center or two identically and symmetrically distributed Pt nozzle nanoengines is for the first time designed and fabricated using an easy-operation layer-by-layer deposition method based on nano-electro-mechanical systems (NEMS) technology, whereby Pt functions as the chemical catalyst for the decomposition of hydrogen peroxide (H₂O₂) to produce oxygen (O₂) bubbles detaching from the surface and water (H₂O), which in turn generates a recoil force thrusting the nanojets to propel forward. The propulsion mechanism originated from the momentum change of a Au–Ni–Pt nanojet-oxygen bubble integral system and the steerable trajectories of the two different shaped nanojets are investigated. Moreover, the nanojet's motion is characterized and recorded in diluted H₂O₂ solution under an optical microscope, revealing that the O₂ bubbles are generated and detached from the surface of Pt catalyzing H₂O₂ decomposition. In addition, the novel Au–Ni–Pt nanojets with one off-center Pt nanoengine can autonomously propel forward circularly, while the Au–Ni–Pt nanojets with two identically and symmetrically distributed Pt nozzle nanoengines can move forward in a linear way.