Nanostellar Inc, Silicon Valley, CA, USA
题目: Mixed Phase Oxide Catalyst Based on Mn-Mullite (Sm, Gd)Mn2O5 for NO Oxidation in Diesel Exhaust
Diesel engines are attractive because of their higher fuel efficiency than gasoline engines. However, their lean exhaust with high oxygen (O2) content requires specialized devices to reduce the engine-generated nitrogen oxide (NOx,) pollutants, mostly nitric oxide (NO) to environmentally benign nitrogen (N2).
Oxidation of nitric oxide for subsequent efficient reduction in selective catalytic reduction or lean NOx trap devices continues to be a challenge in diesel engines because of the low efficiency and high cost of the currently used Pt-based catalysts. We show that mixed-phase oxide materials based on Mn-mullite (Sm, Gd)Mn2O5 are an efficient substitute for the current commercial Pt-based catalysts. Under lab simulated diesel exhaust conditions, this mixed-phase oxide material was superior to Pt in terms of cost, thermal durability and catalytic activity for NO oxidation. This oxide material is active at temperatures as low as 120oC with conversion maxima of ~45% higher than that achieved with Pt. In this contribution, Density functional theory and diffuse reflectance infrared fourier transform spectroscopy provide insights into the NO-to-NO2 reaction mechanism on catalytically active Mn-Mn sites via the intermediate nitrate species.
? The University of Texas at Dallas, U.S.A (2008 spring- 2011 spring) Ph.D in Materials Science and Engineering
Honors and Awards
? “Chinese Academy of Sciences Fellowship” Chinese Academy of Sciences (2003, 2004 and 2005)
? “McNair Graduate Scholarship” The University of Texas at Arlington (2006 and 2007)
? “Scharff Research Award” The University of Texas at Arlington (2007)
? 2011.6 -present, Scientist, Nanostellar Inc, Silicon Valley, CA, USA
Peer-reviewed journal and conference papers
1. R. Subramanian*, P. Bhadrachalam*, W. Wang* (first co-authors), V. Ray, T. Park, J. Kim, K. Cho &S. Koh, “Overcoming the intrinsic limit of Fermi-Dirac thermal smearing”, Nature, (submitted).
2. C. Gong, W. Wang, G. Lee, B. Shan and K. Cho, Electronic transport cross metal-graphene end contacts, Phys. Rev. Lett. (Under review)
3. W. Wang, G. McCool, N. Kapur, G. Yuan, B. Shan, M. Nguyen, U. M. Graham, B. Davis, G. Jacobs, K. Cho, X. Hao, “Mixed Phase Oxide Catalyst Based on Mn-Mullite (Sm, Gd)Mn2O5 for NO Oxidation in Diesel Exhaust”, Science (accepted).
4. C. Gong, D. Hinojos, W. Wang, N. Nijem, B. Shan, R. M. Wallace, K. Cho, and Y. Chabal, Hybrid Metal Electrodes for Fine-Tuning the Electronic Properties of Graphene at Contact Regions, ACS Nano, 6, 5381 (2012).
5. R. C. Longo, K. Xiong, W. Wang, K. Cho, Influence of the exchange-correlation potential on the electrochemical performance of multi component silicate cathode materials, Electrochimica Acta, (accepted).
6. Q. Bai, W. Wang, Qiming Zhang, M. Tao, J. App. Phys., 111, 023709 (2012).
7. W. Wang, W. Yang, R. Chen, X. Duan, Y. Tian, D. Zeng and B. Shan, Investigation of Band offsets of Interface BiOCl:Bi2WO6: a First-Principles Study, Physical Chemistry Chemical Physics, 14, 2450-2454(2012).
8. W. Wang, G. Lee, M. Huang, R.M. Wallace, and K. Cho, First-Principles Study of GaAs (001)-β2(2x4) Surface Oxidation, Microelectronics Engineering, 88, 3419(2011).
9. W. Wang, C. Gong, B. Shan, R.M. Wallace, and KJ Cho, S Passivation Effect on HfO2:GaAs Interface: A DFT Study., Appl. Phys. Lett. 98, 232113 (2011).
10. W. Wang, K. Xiong, R.M. Wallace, and K. Cho, Interfacial Si Effect on Atomic Bonding and Electric Structure at HfO2:GaAs Interface: A first-principles Study, J. App. Phys., 109, 063704 (2011). (selected for the April 4, 2011 issue of Virtual Journal of Nanoscale Science & Technology.)
11. W. Wang, P. Cha, S. Lee, M. Kim, and K. Cho, First Principles Study of Si Etching by CHF3 Plasma Source, Applied surface science. 257, 8767(2011).
12. W. Wang, K.Xiong, R. Wallace, K. Cho, First-Principles Study of Initial Growth of GaΧO Layer on GaAs-β2(2×4) Surface and Interface Passivation by F, J. App. Phys., 110, 103714 (2011).
13. W. Wang, C.L. Hinkle, E.M. Vogel, K. Cho, R.M. Wallace, Is interfacial chemistry correlated to gap states for high-k/III–V interfaces?, Microelectronics Engineering, 88, 1061(2011).
14. H. Yamaguchi, K. Murakami,G. Eda, T. Fujita, P. Guan, W. Wang, C. Gong, J. Boisse, S. Miller, M. Acik, K. Cho, Y. Chabal, M. Chen, F. Wakaya, M. Takai, M. Chhowalla, Field Emission from Atomically Thin Edges of Reduced Graphene Oxide, ACS Nano, 5, 4945(2011).
15. K. Xiong, S. Sobhani, R. P. Gupta, W. Wang, B. E. Gnadeand Kyeongjae Cho,First principles study of electronic structures of dopants in Mg2Si, Mater. Res. Soc. Symp. Proc.,Vol. 1329 (2011), DOI: 10.1557/opl.2011.1239.
16. K. Xiong, W. Wang, R.Pazos and K.Cho, First principles study of defects in solid electrolyte lithium thiophosphate Li7P3S11, Mater. Res. Soc. Symp. Proc. Vol. 1331(2011), DOI: 10.1557/opl.2011. 423.
17. W. Wang, K. Xiong, R.M. Wallace, and K. Cho, Impact of Interfacial Oxygen Content on Bonding, Stability, Band offsets and Interface States of GaAs:HfO2 Interfaces, J. Phys. Chem. C, 114, 22610(2010) (ASAP).
18. W. Wang, K. Xiong, R.M. Wallace, and K. Cho, Origin of HfO2:GaAs Interface States and Interface Passivation: a First Principles Study, Applied surface science, 256(2010) 6569.
19. W. Wang, G. Lee, M. Huang, R.M. Wallace, and K. Cho, First-Principles Study of GaAs (001)-β2(2x4) Surface Oxidation and Passivation with H, Cl, S, F, and GaO, J. App. Phys. 107 (2010), 103720.
20. W. Wang, D. Wu, Q. Zhang, L. Wang and M. Tao, Mechanism of Conduction Type in Cuprous Oxide Synthesized from Solution, J. App. Phys.107, 123717 (2010).
21. W. Wang, R.M. Wallace, and K. Cho, Interfacial Oxygen Content Impact on Band Offsets of GaAs:HfO2 Interface, Mater. Res. Soc. Symp. Proc., 1252-I06-04, 2010.
22. C. Gong, G. Lee, W. Wang, B. Shan, E. M. Vogel, R. M. Wallace and K. Cho, First-Principles and Quantum Transport Studies of Metal-Graphene End Contacts, Mater. Res. Soc. Symp. Proc.，1259-S14-35, 2010.
23. K. Xiong, W. Wang, H. N. Alshareef, R. P. Gupta, J. B. White, B. E. Gnade and KJ Cho, Band Offsets and Stability of Metal/Bi2Te3 Interfaces, Journal of Physics D: Applied Physics,43(2010),115303.
24. K. Xiong, R. P. Gupta, H. N. Alshareef, J. B. White, W. Wang, B. E. Gnade and K. Cho, Behavior of group IIIA impurities in PbTe: implications to improve thermoelectric efficiency, Journal of Physics D: Applied Physics, 43(2010),115303.
25. W. Wang, K. Xiong, G. Lee, M. Huang, R.M. Wallace, and K. Cho, First Principles Study of HfO2:GaAs Interface Passivation by Si and Ge, Mater. Res. Soc. Symp. Proc. 1155-C09-15, 2009.
26. W. Wang, K. Xiong, G. Lee, M. Huang, R.M. Wallace, and K. Cho, Impact of Native Oxides on GaAs/HfO2 Interfaces: A First principles Study, TECHCON in Austin, 2009, 1464.002 (8.09).
27. K. Xiong, W.Wang, H. N. Alshareef, R. P. Gupta, J. B. White, B. E. Gnade and K. Cho, MATERIALS AND DEVICES FOR THERMAL-TO-ELECTRIC ENERGY CONVERSION,1166(2009),103-108.
28. K.Xiong, W. Wang, H. N Alshareef, R. P Gupta, J. B White, B. E Gnade and K. Cho，First Principles Study of Metal/Bi2Te3 Interfaces: Implications to Improve Contact Resistance, Mater. Res. Soc. Symp. Proc.，1166-N05-01，2009.
W. Wang, R.M. Wallace, and K. Cho, “Theoretical progress on GaAs surface and GaAs/high-κ interface” in High-k Gate Dielectrics for CMOS Technology, Gang He editor, Wiley-VCH.