Time：April 26，2014 9：00 a.m.
Location：No. 2 conference room, Energy Conference Center
Lecturer：Dr. Yimin Chao
Energy Materials Lab, School of Chemistry, University of East Anglia, Norwich NR4 7TJ, UK
Introduction：
Yimin Chao obtained his PhD in Nanosciences from Newcastle University in 2004 with a thesis titled Electronic and optical properties of nanostructured materials. He held postdoctoral research fellowship at the Wolfson Chemical Nanosciences Centre at Newcastle between 2004 and 2007 on Nanoscale sensors for genomic and proteomic analysis inside the living cell. He joined UEA in 2007.
Yimin Chao’s research interest is in investigating nanostructured systems, from the basic physical and chemical mechanisms of synthesis, through their optical and electronic properties to energy conversion and biomedical applications. Current research themes include functionalization and characterization of Si quantum dots (Si-QDs); biomedical applications of QDs in targeted and monitored drug delivery; and applications in thermoelectric modules. His research is carried out both at his laboratories at the University of East Anglia and in central facilities in Europe. These include Diamond Light Source (DLS) in the UK, Max-lab in Sweden and European Synchrotron Radiation Facility (ESRF), France.
Abstract:
Over the past 20 years there has been increasing pressure for the development of technologies which take advantage of renewable energy sources. This is a result of the environmental impacts and future availability of fossil fuels.1 There has also been an emphasis on the recycling of waste energy (energy scavenging) to improve the efficiency of many industrial and commercial processes.2
The most common thermoelectric materials used today are based on bismuth telluride.3 ZT values of 2.4 at room temperature have been recorded for thin films, using bismuth telluride alloys, Bi2Te3/Sb2Te3.4 The major drawback with these materials is that the tellurium required to produce them is toxic and also expensive, due to its low abundance. As a consequence there has been a lot of focus on producing thermoelectric materials from alternative sources such as silicon,5 conductive polymers,6 and magnesium silicide.7Silicon is a promising alternative to current thermoelectric materials (Bi2Te3). Silicon nanoparticle based materials show especially low thermal conductivities due to the high number of interfaces, which increases the observed phonon scattering. The major obstacle with these materials is maintaining a high electrical conductivity. Surface functionalization with phenylacetylene shows an electrical conductivity of 18.1 S m-1 and seebeck coefficient of 3228.8 μV K-1 as well as maintaining a thermal conductivity of 0.1 W K-1 m-1. This gives a ZT of 0.6 at 300 K which is significant for a bulk silicon based material and is similar to that of other thermoelectric materials such as Mg2Si, PbTe and SiGe alloys.
Nanosize silicon (10 nm diameter) reacts with water to generate hydrogen 1000 times faster than bulk silicon, 100 times faster than previously reported Si structures, and 6 times faster than competing metal formulations. The H2production rate using 10 nm Si is 150 times that obtained using 100 nm particles, dramatically exceeding the expected effect of increased surface to volume ratio.These results imply that nanosilicon could provide a practical approach for on-demand hydrogen production without addition of heat, light, or electrical energy.8
Keywords: Silicon nanoparticles; Thermoelectrics; Hydrogen generation; Water splitting; Fuel cell
1. (a) Schneider, S. H., Science 1989,243 (4892), 771-781; (b) Solomon, S.; Plattner, G.-K.; Knutti, R.; Friedlingstein, P., Proceedings of the National Academy of Sciences 2009,106 (6), 1704-1709.
2. Hora？k, D.; Babi？, M.; Jendelova？, P.; Herynek, V.; Trchova？, M.; Pientka, Z.; Pollert, E.; Ha？jek, M.; Sykova？, E., Bioconjugate Chemistry 2007,18 (3), 635-644.
3. Poudel, B.; Hao, Q.; Ma, Y.; Lan, Y.; Minnich, A.; Yu, B.; Yan, X.; Wang, D.; Muto, A.; Vashaee, D.; Chen, X.; Liu, J.; Dresselhaus, M. S.; Chen, G.; Ren, Z., Science 2008,320 (5876), 634-638.
4. Venkatasubramanian, R.; Siivola, E.; Colpitts, T.; O'Quinn, B., Nature 2001,413 (6856), 597-602.
5. (a) Tang, J.; Wang, H.-T.; Lee, D. H.; Fardy, M.; Huo, Z.; Russell, T. P.; Yang, P., Nano Letters 2010,10 (10), 4279-4283; (b) Boukai, A. I.; Bunimovich, Y.; Tahir-Kheli, J.; Yu, J. K.; Goddard, W. A.; Heath, J. R., Nature 2008,451, 168-171; (c) Hochbaum, A. I.; Chen, R. K.; Delgado, R. D.; Liang, W. J.; Garnett, E. C.; Najarian, M.; Majumdar, A.; Yang, P. D., Nature 2008,451, 163-167.
6. Bubnova, O.; Crispin, X., Energy & Environmental Science 2012,5 (11), 9345-9362.
7. Zaitsev, V. K.; Fedorov, M. I.; Gurieva, E. A.; Eremin, I. S.; Konstantinov, P. P.; Samunin, A. Y.; Vedernikov, M. V., Physical Review B 2006,74 (4), 045207.
8. Erogbogbo, F.; Lin, T.; Tucciarone, P. M.; LaJoie, K. M.; Lai, L.; Patki, G. D.; Prasad, P. N.; Swihart, M. T., Nano Letters 2013,13 (2), 451-456.