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
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.
Wallace Leung received his BS in Mechanical and Aerospace Engineering from Cornell, and MS and ScD in Mechanical Engineering from MIT.
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.
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