Date of Award

2018-01-01

Degree Name

Master of Science

Department

Physics

Advisor(s)

Srinivasa R. Singamaneni

Abstract

Magnetism and catalytic activity of nanoscale layered two-dimensional (2D) transition metal dichalcogenides (TMDs) have gained an increasing research interest in the recent past. To broaden the current knowledge and understanding on this subject, in this work, together with my collaborators, I study the magnetic and electrocatalytic properties of hydrothermally grown pristine and transition metal doped (10% of Co, Ni, Fe and Mn) 2H-MoS2 nanosheets/nanocrystals (NCs), with the particle size of 25-30 nm. A broad range of experimental measurements such as x-ray diffraction, transmission electron microscopy, x-ray photo absorption spectroscopy, Raman spectroscopy, magnetic, catalytic and electron spin resonance have been employed to characterize these materials. It has been shown that the room temperature magnetic properties of these nanostructures strongly depend on the nature of dopant, in which, Co, Ni, and Fe doping produces characteristic room temperature ferromagnetism, whereas, Mn doping exhibits stronger paramagnetic features. All the materials showed features related to canted antiferromagnetism at lower temperatures. Among all, Co doped MoS2 NCs showed stronger catalytic activity and Mn doped MoS2 NCs showed weaker catalytic activity. These experimental findings combined with electron spin resonance measurements infer that the increasing number of catalytically active sites in Co doped MoS2 NCs might be responsible for its superior electrocatalytic activity. The present results show that the magnetic order-disorder behavior and catalytic activity can be modulated by choosing the suitable dopants in NCs of 2D materials.

Language

en

Provenance

Received from ProQuest

File Size

59 pages

File Format

application/pdf

Rights Holder

Luis Martinez

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