TITLE:
Experimental and Theoretical Properties of MoS2+x Nanoplatelets
AUTHORS:
D. H. Galvan, A. Posada Amarillas, N. Elizondo, M. José-Yacamán
KEYWORDS:
Hydrodesulfurization; Tight-Binding; Catalyst; Tem; Clusters
JOURNAL NAME:
Modern Research in Catalysis,
Vol.2 No.4,
October
30,
2013
ABSTRACT:
The synthesis and the catalysis in the HDS of DBT
reaction of nanostructured self-supported catalyst containing MoS2+x nanoplatelets have been investigated. Enhancement of higher activity observed
in sulfide catalyst sample (d) with respect to the ex situ and in situ references is more closely related to the morphology change of particles
(nanoplatelets). In this work, we suggest that certain structures present in
model catalysts maybe related to low dimensional structures and present a
theoretical study of two MoS2 clusters (one made of 34 atoms/cluster
and the second one made of 41 atoms/cluster), to these clusters seven sulfur
atoms were randomly located at the surface of the sulfur layer, in order to
simulate certain structures resembling arrow shaped nanoplatelets that were
found in a High Resolution TEM analysis performed in some MoS2 samples. Additionally, one of the goals is to enquire about the electronic
properties presented in such structures when the clusters terminated as Moor
S-edge and if it could be correlated to the catalyst 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 Conductions bands respectively. Moreover,
to the same clusters enunciated formerly, when the sulfur atoms
were located at the surface of the S-layer, for the first cluster (34
atoms/cluster) yielded a more metallic behavior, while the second one (41
atoms/cluster) yielded an isolator behavior. Our results agree with the
experimental and theoretical results presented by several groups in
different laboratories arriving to the conclusion that the S-Mo-S Mo-edge arrow
heads structures could be responsible to the enhancement of the catalytic
activity on the MoS2 studied samples.