Date: August 5, 2010
Time: 1:30 p.m.
Location: Wallberg Memorial Building, Room 116
Speaker: Professor Peidong Yang, University of California, Berkeley
Abstract: Direct solar energy conversion to storable fuels such as hydrogen offers a promising route toward less reliance on fossil fuels. Photoelectrolysis of water to generate H2 on a semiconductor/electrolyte interface has the attractive advantages of clean processing and energy savings over steam reforming of natural gas. One of the most critical issues in solar water splitting is the development of a photoanode with high efficiency and long-term durability in an aqueous environment. Semiconductor nanowires represent an important class of nanostructure building block for photovoltaics as well as direct solar-to-fuel application because of their high surface area, tunable bandgap and efficient charge transport and collection. In this talk, I will highlight several recent examples in this lab using semiconductor nanowires and their heterostructures for the purpose of solar energy harvesting. In addition, we have also discovered that the thermoconductivity of the silicon nanowires can be significantly reduced due to phonon scattering, pointing to a very promising approach to design better thermoelectrical materials. It is important to note that the engines that generate most of the world’s power typically operate at only 30–40 per cent efficiency, releasing roughly 15 terawatts of heat to the environment. If this “wasted heat” could be recycled, the impact globally would be enormous. The silicon nanowire thermoelectric work should have a significant impact in alternative energy generation.
Biography: Peidong Yang received a B.S. in chemistry from University of Science and Technology of China in 1993 and a Ph.D. in chemistry from Harvard University in 1997. He did postdoctoral research at University of California, Santa Barbara before joining the faculty in the department of Chemistry at the University of California, Berkeley in 1999. He is currently Miller professor in the Department of Chemistry, Materials Science and Engineering; and a senior faculty scientist at the Lawrence Berkeley National Laboratory. He is the deputy director for the Center of Integrated Nanomechanical Systems. He is an associate editor for Journal of the American Chemical Society and also serves on editorial advisory board for number of journals including Acct. Chem. Res. and Nano. Lett. He was the first chairperson for the Nanoscience subdivision within American Chemical Society. He is the recipient of Alfred P. Sloan research fellowship, the Arnold and Mabel Beckman Young Investigator Award, National Science Foundation Young Investigator Award, MRS Young Investigator Award, Julius Springer Prize for Applied Physics, ACS Pure Chemistry Award, and Alan T. Waterman Award. His main research interest is in the area of one dimensional semiconductor nanostructures and their applications in nanophotonics, energy conversion and living cell interface.