The Waterloo Institute for Nanotechnology (WIN) and the Faculty of Engineering are pleased to present a Distinguished Lecture Series talk by Professor Wallace Leung, Chair Professor of Innovative Products and Technologies and a distinguished professor of mechanical engineering at Hong Kong Polytechnic University.
Novel Nanofiber Technologies for Energy and Environment
Abstract
Applications of nanofibers, made of organic and inorganic materials in various novel configurations, can address the global challenges in clean energy, air and water.
The immense magnitude of the solar energy available can be many times that of our annual global energy demand. Unfortunately, the high-cost, low-efficiency photovoltaics render the technology from being considered. An environmentally friendly Dye Sensitized Solar Cell (DSSC) uses an organic dye to effectively harvest solar energy and convert efficiently photons to electrons. Three novel nanofiber technologies for the photoanode of DSSC will be discussed for improving energy harvest, energy trapping, and charge transport, respectively. Nanofiber for improving crystal quality and electron transport are also used for the perovskite solar cells, resulting in efficiency that tops 20%.
Pollutants
in
form
of
gas
and
particulate
have
been
responsible
for
pollution
leading
to
chronic
health
problems.
Filtration
using
nanofibers
arranged
in
a
multiple-layer
configuration
can
realize
low
pressure
drop
yet
high
filtration
efficiency
for
nano-aerosols
(about
100
nm).
Recently,
electrostatic
charged
nanofibers
have
been
developed
that
induce
electrical
dipoles
on
neutrally
charged
particles,
thereby
improving
capture.
For
nanofibers
that
have
been
loaded
with
aerosols,
effective
cleaning
can
be
realized
to
remove
trapped
aerosols
for
filter
reuse.
A
suite
of
nanofiber-based
photocatalysts
has
been
developed
to
convert
harmful
gases
(VOC,
NOx)
to
harmless
gases.
The
composite
nanofibers
photocatalysts
are
made
primarily
of
N-type
semiconductors
that
work
synergistically
to
harvest
the
entire
light
spectrum
producing
effectively
radicals
to
oxidize
the
adsorbed
gaseous
pollutant
molecules,
viruses
and
bacteria.
The
photocatalyst
works
equally
well
to
breakdown
harmful
organics
dissolved
in
water.
Finally, a semi-conductor nanofiber with 80-nm diameter embedded with graphene in a roll-up form, that eliminates edge effect associated with 2D graphene sheet, is discussed. The hybrid material has both semiconductor and conductor properties that proved advantageous for solar cells, photocatalysis and sensors.
Biography
Since 2005, Wallace is Chair Professor of Innovative Products and Technologies in Mechanical Engineering at Hong Kong Polytechnic University (PolyU). He has developed novel nanofiber technologies for photovoltaics and air/water purification, resulting in a start-up company. In 2005, Dr. Leung was the Founder and Director of the new Research Institute of Innovative Products and Technologies collaborating with various PolyU’s departments and hospital physicians developing health technologies on decision support systems, blind navigation, smart osteoarthritis treatment, and interactive robots for stroke rehabilitation.
Previously, Professor Leung has worked in the United States for 25 years, respectively, for Gulf R&D, Schlumberger, and Baker-Hughes/Bird, for which he has developed various separation technologies. Later, he found Advantech with focus on biopharmaceutical separation.
Professor Leung has published 32 SCI papers on nanofibers alone and numerous papers on other topics. He is author of two texts and holds 52 United States patents. Prof. Leung is transdisciplinary with expertise in mechanical, chemical, material science, environmental, mineral processing, biotechnology and aerospace engineering. He a fellow of ASME, AICHE, AFS, HKIE and the Hong Kong Academy of Engineering Sciences.