Autonomously Moving Nanorods at a Viscous Interface

• Published in: Nano letters Vol. 6; no. 1; pp. 66 - 72
• Main Authors: Dhar, P, Fischer, Th. M, Wang, Y, Mallouk, T. E, Paxton, W. F, Sen, A
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-01-2006
• Subjects: Chemistry; Electrochemistry; Electrodes: preparations and properties; Exact sciences and technology; General and physical chemistry; Monolayer; Gold; Fluctuations; Transition metal; Surfactant; Experimental study; Inorganic compound; Shear viscosity; Bar; Asymmetry; Platinum; Dissipation; Concentration effect; Friction coefficient; Correlation function; Anomaly; Diffusion; Catalyst activity; Nanostructured materials; Nanorod; Interface
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl052027s

We study the autonomous motion of catalytic nanorods in Gibbs monolayers. The catalytic activity of the rods on a hydrogen peroxide aqueous subphase gives rise to anomalous translational and rotational diffusion. The rods perform a Levy-walk superdiffusive motion that can be decomposed into thermal orientation fluctuations and an active motion of the rods with a constant velocity along their long axis. Since interfacial dissipation increases relative to bulk phase dissipation when miniaturizing the size of objects moving in the interface, the autonomous nanorods allow for precise measurements of surface shear viscosities as low as a few nN s/m. The cross over from active motion toward passive diffusion when increasing the surfactant concentration is explained by a loss of friction asymmetry of the rods.