Catalytic Locomotion of Core-Shell Nanowire Motors

Bumjin Jang; Wang, Wei; Wiget, Samuel; Petruska, Andrew; Chen, Xiangzhong; Hu, Chengzhi; Hong, Ayoung; David Folio; Antoine Ferreira; Salvador Pané; Nelson Bradley

doi:10.1021/acsnano.6b04224

Abstract

We report the partial 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 Au/Ru core-shell nanowires show both a noticeable decrease in rotational diffusivity and increase in motor speed with nanowire length. Numerical modelling based on self-electroosmosis attributes the 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 peculiar speed increase of Au/Ru core-shell nanomotors with length, but also the large variation in speeds 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.

Keywords: electrodeposition, core−shell nanowires, catalytic nanomotors, self-electroosmosis, self-diffusiophoresis, net propulsive force

Acknowledgements

Funding support from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement 296679 (MANAQA) is acknowledged. S.P. acknowledges financial support by the European Research Council Starting Grant “Magnetoelectric Chemonanomotorics for Chemical and Biomedical Applications (ELECTROCHEMBOTS)”, by the ERC grant agreement no. 336456. W.W. is grateful for the ﬁnancial support from National Natural Science Foundation of China (grant no. 11402069) and the city government of Shenzhen (grant no. KQCX20140521144102503). We especially thank Prof. Mahmut Selman Sakar from the Mechanical Engineering (School of Engineering, EPFL), and Carlos C. J. Alcantara from the Multi-Scale Robotics Lab (ETH Zürich) for constructive discussions.

Supporting Information

The Supporting Information is available free of charge on the ACS Publications website at 10.1021/acsnano.6b04224.

Movie S1: A motion comparison of Au/Ru core-shell nanowires at different lengths
Movie S2: A motion comparison among Au/Rh, Rh/Au and Au/Ru core-shell nanowires
Supplement file: Numerical modeling procedures and additional numerical modeling results of the effect of core protrusion on the speed of nanomotors and supporting figures

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Citation

BibTeX citation:

@article{jang2016,
  author = {Jang, Bumjin and Wei , Wang and Samuel , Wiget and Andrew ,
    Petruska and Xiangzhong , Chen and Chengzhi , Hu and Ayoung , Hong
    and Folio, David and Ferreira, Antoine and Pané, Salvador and
    Bradley, Nelson},
  publisher = {American Chemical Society (ACS)},
  title = {Catalytic {Locomotion} of {Core-Shell} {Nanowire} {Motors}},
  journal = {ACS Nano},
  volume = {10},
  number = {11},
  pages = {9983-9991},
  date = {2016-10-18},
  url = {https://dfolio.fr/publications/articles/2016jangACS.html},
  doi = {10.1021/acsnano.6b04224},
  issn = {2640-4567},
  langid = {en},
  abstract = {We report the partial 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 Au/Ru
    core-shell nanowires show both a noticeable decrease in rotational
    diffusivity and increase in motor speed with nanowire length.
    Numerical modelling based on self-electroosmosis attributes the
    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 peculiar speed increase of Au/Ru
    core-shell nanomotors with length, but also the large variation in
    speeds 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.}
}

For attribution, please cite this work as:

Jang B., Wei W., Samuel W., Andrew P., Xiangzhong C., Chengzhi H., Ayoung H., Folio D., Ferreira A., Pané S., and Bradley N., “Catalytic Locomotion of Core-Shell Nanowire Motors,” ACS Nano, vol. 10, pp. 9983–9991, October 2016. [Online]. Available: https://dfolio.fr/publications/articles/2016jangACS.html