Electronic Theses and Dissertations

Identifier

6408

Date

2019

Document Type

Thesis

Degree Name

Master of Science

Major

Physics

Concentration

Computational Physics

Committee Chair

Xiao Shen

Committee Member

Chenhui Peng

Committee Member

Sanjay Mishra

Abstract

Single-layer MoS2 has been shown to excel in many applications like as a catalyst, supercapacitor, transistor, and biosensor. It has been shown that there is a correlation between the catalytic activity and the metallic character of the surface. Consequently, the metallic phase of MoS2 has been shown to surpass the performance of the semiconducting phase. However, the metallic phase is less energetically favorable than the semiconducting 2H phase, and it is unstable in air. Recently, it has beenshown that a metallic phase of MoS2 is stable in water. This metallic phase is also found to be hydrophilic which provides additional advantages in applications as a supercapacitor or biosensor. We attribute this metallic phase to 1T'-MoS2 and investigate the origin of the hydrophilic behavior. Through first-principles calculations, we found that, with a sulfur vacancy on the surface, dissociative adsorption of a water molecule is favorable only on the 1T' surface. The water dissociation on the surface not only increases the hydrophilicity of the surface, but it also explains the enhanced stability of 1T'-MoS2 in water by reducing the energy difference between the 1T' and 2H phases.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.

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