Na tarde desta sexta-feira (5), a partir das 16h, acontece o Colóquio do Departamento de Física no auditório do DF, localizado no Centro de Ciências Exatas e da Natureza (CCEN). O tema do colóquio é “Understanding Co/MoS2 materials using high-resolution TEM” e será apresentado por Manuel Ramos, do Departamento de Física y Matemáticas, UACJ-Instituto de Ingeniería y Tecnología, México.

Resumo

The catalytic sites of cobalt promoted MoS2 catalytic materials is present in here by meaning of field emission transmission electron microscopy in scanning and transmission mode. The aim is to depict crystallographic and electronic structure on those materials. Our results indicate that sulfur termination sites are more idealistic (energetic favorable [eV]) for adsorption of sulfur-content molecules as reflected by density functional theory computer assisted calculations. The usage of electron microscopy to determine structure/function relationships on nano-scaled catalytic materials has brought great insights, mainly when studying cobalt-promoted MoS2 unsupported catalyst [1,2]. On the other hand, the development of computer assisted code to determine electronic structure as based in “density” methods allows to understand many aspects such as electronic donation from cobalt into molybdenum as both shared sulfur bonding [1], oxidation process and carburization aspects [3]. In that regards, we present in here two fundamental aspects: 1) Molecular structure of mixed phase of Cobalt sulfide and Molybdenum Sulfide (Co9S8/MoS2) based on experimental observations made by electron microscopy. 2) The catalytic sites of the as proposed molecular bulk model [1]. Our results indicate vertical contact between MoS2 slabs onto (111)-Co9S8 planes and the electronic structure reveals a high metallic character with sulfur termination as most active sites for adsorption of sulfur content molecules as calculated using transitional states by Halgren-Lipscomb algorithm. 3) Co/MoS2 were also synthesized by hydrothermal methods and final products highly investigated by both as mentioned techniques.