2H/1T Phase Transition of Multilayer MoS2 by Electrochemical Incorporation of S Vacancies

By Xiaorong Gan, L. Lee, Kwok‐yin Wong, Tsz Wing Lo, K. Ho, D. Lei, Huimin Zhao. ACS Applied Energy Materials, 2018

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The phase transition of multilayer MoS2 nanosheets from semiconducting 2H to metallic 1T (2H/1T) has been realized mainly by chemical methods (e.g., Li intercalation). Here, we develop a simple yet effective method, cyclic voltammetry, to successfully tune the 2H/1T phase transition of multilayer MoS2 nanosheets without using intercalation species. The phase transition is triggered by the electrochemical incorporation of S vacancies (obtained by electrochemical etching), which on the one hand injects electrons into the framework of S–Mo–S and on the other hand facilitates the sliding of S planes. Density functional theory calculations show that O doping in the framework of S–Mo–S decreases the energy barrier for forming S vacancies and stabilizes the 1T-phase by occupying the 4d orbital of Mo. Our calculations further show that the presence of S vacancies and O incorporation not only reduces the bandgap of MoS2, indicating an increased conductivity, but also decreases the hydrogen adsorption free energy, ...

Subfields: Electrical and Electronic Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/33a0bc14925d1e594f0e166acfd925bf88a8b01d