title: Catalytically powered dynamic assembly of rod-shaped nanomotors and passive tracer particles.
abstract: Nano- and microscale motors powered by catalytic reactions exhibit collective behavior such as swarming, predator-prey interactions, and chemotaxis that resemble those of biological microorganisms. A quantitative understanding of the catalytically generated forces between particles that lead to these behaviors has so far been lacking. Observations and numerical simulations of pairwise interactions between gold-platinum nanorods in hydrogen peroxide solutions show that attractive and repulsive interactions arise from the catalytically generated electric field. Electrokinetic effects drive the assembly of staggered doublets and triplets of nanorods that are moving in the same direction. None of these behaviors are observed with nanorods composed of a single metal. The motors also collect tracer microparticles at their head or tail, depending on the charge of the particles, actively assembling them into close-packed rafts and aggregates of rafts. These motor-tracer particle interactions can also be understood in terms of the catalytically generated electric field around the ends of the nanorod motors.
authors.affiliation: Department of Chemistry, Pennsylvania State University, University Park, PA 16802.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Wentao
authors.initials: W
authors.lastname: Duan
authors.forename: Ayusman
authors.initials: A
authors.lastname: Sen
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Mallouk
mesh_terms: D032701:Biomimetics; D002384:Catalysis; D004560:Electricity; D020342:Finite Element Analysis; D006046:Gold / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D008956:Models, Chemical; D043942:Nanotubes / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry
chemical_list: D010984:Platinum; D006046:Gold; D006861:Hydrogen Peroxide
keywords: colloidal transport; dynamic interactions; self-assembly