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Identifier

000432856

Title

Theoretical study of MoS2 defects and dopants for hydrogen evolution reaction

Alternative Title

Θεωρητική μελέτη ατελειών και προσμίξεων διθειούχου μολυβδαινίου (ΜΘS2) για την αντίδραση παραγωγής υδρογόνου

Author

Μινωτάκη, Μαρία

Thesis advisor

Κοπιδάκης, Γεώργιος

Reviewer

Αρματάς, Γεράσιμος
Ρεμεδιάκης, Ιωάννης

Abstract

Hydrogen is one of the predominant clean and renewable alternatives to fossil fuels. Effi¬cient and sustainable hydrogen production is key to its widespread use as an energy carrier in the near future. Catalysts based on precious metals are currently used in hydrogen evolu¬tion reaction (HER). Molybdenum disulfide (MoS2) is an earth-abundant, low cost, layered material with a variety of interesting properties, which depend on its dimensionality and structure. Previous work has established that while basal planes of MoS2 nanostructures are inert, their edges are catalytically active in HER. In an effort to increase the number of active sites for HER in MoS2 nanoparticles, Density Functional Theory (DFT) calculations were performed to examine the hydrogen adsorption ability of MoS2 basal plane when mod¬ified by defects and dopants. The hydrogen adsorption free energy (AGH) was employed as the main activity descriptor. Introduction of a sulfur vacancy in combination with a nearby Mo-atom substitution by a transition metal enhance basal plane activity. Parameters such as hydrogen adsorption sites, hydrogen coverage, hydrogen molecule desorption mechanisms, and stability, are examined. Our findings suggest that the combination of a single Ni atom dopant and a sulfur vacancy formation in the MoS2 basal plane has the maximum perfor¬mance compared to several other metal dopants. Results with other transition metals provide insight into the activation mechanism of the MoS2 basal plane. A volcano relationship exists between activity descriptor and exchange current density. The relationship between activity and stability descriptors for these systems is also examined. Finally, guidelines for the design of efficient and stable MoS2-based catalysts for HER using DFT calculations are outlined.

Language

English

Subject

Density functional theory calculatios

transition metals

Διθειούχο μολυβδαίνιο

Μεταβάτικά μέταλλα

Issue date

2020-11-27

Collection

School/Department--School of Sciences and Engineering--Department of Materials Science and Technology--Post-graduate theses

Type of Work--Post-graduate theses