title: Catalytic Locomotion of Core-Shell Nanowire Motors.
abstract: We report Au/Ru core-shell nanowire motors. These nanowires are fabricated using our previously developed electrodeposition-based technique, and their catalytic locomotion in the presence of H2O2is investigated. Unlike conventional bimetallic nanowires that are self-electroosmotically propelled, our open-ended Au/Ru core-shell nanowires show both a noticeable decrease in rotational diffusivity and increase in motor speed with increasing nanowire length. Numerical modeling based on self-electroosmosis attributes decreases in rotational diffusivity to the formation of toroidal vortices at the nanowire tail, but fails to explain the speed increase with length. To reconcile this inconsistency, we propose a combined mechanism of self-diffusiophoresis and electroosmosis based on the oxygen gradient produced by catalytic shells. This mechanism successfully explains not only the speed increase of Au/Ru core-shell nanomotors with increasing length, but also the large variation in speed among Au/Ru, Au/Rh, and Rh/Au core-shell nanomotors. The possible contribution of diffusiophoresis to an otherwise well-established electroosmotic mechanism sheds light on future designs of nanomotors, at the same time highlighting the complex nature of nanoscale propulsion.
authors.affiliation: Institute of Robotics and Intelligent Systems, ETH Zurich , Zurich, CH-8092, Switzerland.
authors.forename: Bumjin
authors.initials: B
authors.lastname: Jang
authors.affiliation: Shenzhen Key Laboratory for Advanced Materials, School of Material Sciences and Engineering, Shenzhen Graduate School, Harbin Institute of Technology , University Town, Shenzhen 518055, China.|Center for Soft and Living Matter, Institute for Basic Science (IBS) , Ulsan 44919, Republic of Korea.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Institute of Robotics and Intelligent Systems, ETH Zurich , Zurich, CH-8092, Switzerland.
authors.forename: Samuel
authors.initials: S
authors.lastname: Wiget
authors.affiliation: Institute of Robotics and Intelligent Systems, ETH Zurich , Zurich, CH-8092, Switzerland.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Petruska
authors.affiliation: Institute of Robotics and Intelligent Systems, ETH Zurich , Zurich, CH-8092, Switzerland.
authors.forename: Xiangzhong
authors.initials: X
authors.lastname: Chen
authors.affiliation: Institute of Robotics and Intelligent Systems, ETH Zurich , Zurich, CH-8092, Switzerland.
authors.forename: Chengzhi
authors.initials: C
authors.lastname: Hu
authors.affiliation: Institute of Robotics and Intelligent Systems, ETH Zurich , Zurich, CH-8092, Switzerland.
authors.forename: Ayoung
authors.initials: A
authors.lastname: Hong
authors.affiliation: INSA Centre Val de Loire, Universite d'Orléans , PRISME EA, Bourges 4229, France.
authors.forename: David
authors.initials: D
authors.lastname: Folio
authors.affiliation: INSA Centre Val de Loire, Universite d'Orléans , PRISME EA, Bourges 4229, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Ferreira
authors.affiliation: Institute of Robotics and Intelligent Systems, ETH Zurich , Zurich, CH-8092, Switzerland.
authors.forename: Salvador
authors.initials: S
authors.lastname: Pané
authors.affiliation: Institute of Robotics and Intelligent Systems, ETH Zurich , Zurich, CH-8092, Switzerland.
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Nelson
keywords: catalytic nanomotors; core−shell nanowires; electrodeposition; net propulsive force; self-diffusiophoresis; self-electroosmosis