Combining Theory and Experiment: Growth and Structure of 2D Cobalt Sulfide on Au(111)
- Tuesday 31 March 2020
- Hotel NH Noordwijk Conference Centre Leeuwenhorst
Dajo Bodena, Mahesh K. Prabhua, Marcel J. Rostb, Jörg Meyera and Irene M.N. Groota
aLeiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
bLeiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
Since the discovery of graphene, the interest in atomically-thin 2-dimensional (2D) materials with unique mechanical and electronic properties has skyrocketed. One important class of 2D materials involves transition metal dichalcogenides (TMDCs), consisting of a transition metal sandwiched between two layers of chalcogenides (S, Se, Te). TMDCs often exhibit a unique electronic structure interesting for both catalysis and semi-conductor industries.1
TMDCs containing cobalt were previously overlooked, as bulk CoS2 is not layered like MoS2 or graphite. DFT-investigations of freestanding 2D TMDCs reported 2D CoS2 as not stable.2 Nevertheless, our STM results indicate the presence of 2D CoS2 on Au(111), which can only be supported by DFT if the gold surface is also included explicitly in the DFT calculations. In H2S-rich gas atmosphere, a reconstructed 2D CoS2-x sheet forms beyond the thiol desorption temperature. After cooling down it undergoes further sulfidation and becomes 2D CoS2 sheet. With DFT, we show the CoS2 sheet is metallic and has a structure similar to TiS2 and ReS2.3 Based on these results, CoS2 can be added to the list of TMDCs available for development of new materials with novel electronic and mechanical properties.
The authors would like to thank NWO for computer time on the Cartesius facility (grant number: 17216).
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