Catalytic locomotion of Au/Ru core-shell nanowire motors

Bumjin Jang, (1) , Wang Wei (2) , Samuel Wiget, (1) , Petruska J. Andrew (1) , Xiangzhong Chen, (1) , Chengzhi Hu, (1) , Ayoung Hong, (1) , David Folio (3) , Antoine Ferreira (3) , Salvador Pané (1) , Nelson J Bradley (1)

1 IRIS - Institute of Robotics and Intelligent Systems
2 Center for Soft and Living Matters
3 INSA CVL - Institut National des Sciences Appliquées - Centre Val de Loire

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 H2O2 is 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.

Mots clés: nanorobotics; core-shell nanowires; self-diffusiophoresis; self- electroosmosis; catalytic nanorod

Domaines: Automatique / Robotique

Bumjin Jang,, Wang Wei, Samuel Wiget,, Petruska J. Andrew, Xiangzhong Chen,, et al.. Catalytic locomotion of Au/Ru core-shell nanowire motors. ACS Nano, 2016, 10 (11), ⟨10.1021/acsnano.6b04224⟩. ⟨hal-01410107⟩