Electronic properties of the S-Mo-S cluster

PETR 8

D. H. Galvan, donald@ccmc.unam.mx1, A. Posada-Amarillas Sr., posada@cajeme.cifus.uson.mx2, G. A. Camacho, camacho@che.utexas.edu3, N. Elizondo3, L. Allerd4, D. Blom4, and M. Jose-Yacaman, yacaman@che.utexas.edu5. (1) Department of Chemical Engineering, Department of Chemical Engineering, University of Texas at Austin, Austin TX, 78712 and On Sabbatical from CCMC-UNAM, 1 University Station MC:C0400, Austin, TX 78712, (2) Departamento de Investigaciones en Fisica, universidad de Sonora, Apartado Postal 5-088, Hermosillo, 83190, Mexico, (3) Chemical Engineering, Department of Chemical Engineering, University of Texas at Austin, Austin TX, 78712, 1 University Station MC:C0400, Austin, TX 78712, (4) HTML, HTML Oak Ridge National Laboratory, P. O. Box 2008, Oak Ridge, TN 37831, (5) Department of Chemical Engineering, Department of Chemical Engineering, University of Texas at Austin, Austin TX, 78712, 1 University Station MC:C0400, Austin, TX 78712
In this work we suggest that certain structures present in model catalysts may be related to low dimensional structures and present a theoretical study on MoS2 clusters (one made of 34 atoms/cluster and the second one made of 41 atoms/cluster), in order to simulate certain structures resembling arrow heads that were found in a High Resolution TEM analysis performed on MoS2 samples. Furthermore, the main interest is to enquire about the electronic properties presented in such structures when the clusters terminated as Mo- or S-edge, and if it could be correlated to the catalytic behavior of these compounds. To the 34 atoms/cluster Mo-edge yielded metallic behavior while the second cluster the 41 atoms/cluster S-edge yielded a semiconductor behavior with a forbidden energy gap Eg of the order of 3.6 eV between the Valence and Conduction bands respectively. Our results agree with the experimental-theoretical results presented by several groups in different laboratories, arriving to the conclusion that the S-Mo-S Mo-edge arrow heads structure could be responsible to the enhancement of the catalytic activity on the MoS2 studied samples.
 

2nd International Symposium on Hydrotreating/Hydrocracking Technologies
8:30 AM-11:50 AM, Sunday, 10 September 2006 Palace -- Presidio Room, Oral

Division of Petroleum Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006