期刊
ACS NANO
卷 10, 期 11, 页码 9983-9991出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.6b04224
关键词
electrodeposition; core-shell nanowires; catalytic nanomotors; self-electroosmosis; self-diffusiophoresis; net propulsive force
类别
资金
- European Community [296679]
- European Research Council
- ERC [336456]
- DGIST-ETH Microrobotics Centre
- National Natural Science Foundation of China [11402069]
- city government of Shenzhen [KQCX20140521144102503]
- European Research Council (ERC) [336456] Funding Source: European Research Council (ERC)
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.
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