Abstract
Micro/nanomotors (MNMs) are micron to nano sized particles that can produce autonomous
motion via harvesting energy from surrounding environments. As an emerging material,
MNMs have been proposed for applications in biomedicine, environmental remediation, and
complex system modelling. Despite the considerable promise of MNMs in applicational fields,
their fundamental propulsion mechanisms are sometimes deceptively elusive, which raises
challenges in the precise control of the motion.
In this thesis, I investigate the potential relationship between propulsion mechanisms and
motion performance of MNMs. Three exemplary MNMs with different propulsion
mechanisms are prepared by advanced nanofabrication strategies. Theories and
mathematical models are proposed and discussed as to the precise nature of the mechanism
of motion. Results reveal that the propulsion mechanisms are significantly dependent on the
structural properties of MNMs, and the propulsion mechanisms can further influence the
motion behaviour of MNMs.
The first MNM is a flask-shaped carbon-Pt-fatty acids nanomotor that can switch between
self-diffusiophoresis and bubble propulsion in response to light signal. The second MNM is a
flask-shaped Pt-SiO2 nanomotor. This work aims to study the effect of structural factors on
the propulsion mechanisms. The third nanomotor is a TiO2-SiO2-carbon nanomotor that can
switch between self-diffusiophoresis and self-thermophoresis in response to wavelength of
light. During the course of a series of work, I find that the switch of propulsion mechanisms
can lead to the change of speed and motion directionality of MNMs, which provides a new
dimension for advanced motion manipulation of MNMs.
Collectively, this thesis is on the basis of synthetic development to produce MNMs with
variable propulsion mechanisms. It is hoped that this research can provide paradigmatic
insights in understanding the relationship between structures, mechanisms, and performance,
and inspire the design of novel MNMs that can bridge the gap between laboratory and
industry.