Optimization of Chemical Vapor Deposition Method for Growth of MoS2 Nanoflower Structures

Transition metal dichalcogenides (TMD) and their layered structures have recently become the focus of a growing body of academic research for their unique properties and versatility.  One TMD in particular, MoS_2, has shown potential in catalytic surfaces for hydrogen evolution reactions (HER), ^[1] lithium ion battery (LiB) electrodes, ^[2] and semiconductors. ^[3] This increased interest has resulted in a growing need for facile synthesis methods in a variety of morphologies; specifically MoS₂ structures with high density of exposed epitaxial edges are preferred due to their increased electrochemical activity. ^[4]  Nanoflowers allow for high density of the edges while maintaining small facial areas arranged in self-assembling and self-supporting structure without the need for other materials.   

Current methods of synthesis such as mechanical and chemical exfoliation ^[5] as well as autoclave growth ^[6]are plagued with issues including low sample size, exotic and hazardous reagents, and extensive growth times for often imperfect samples with minimal exposure of edge sites. 

High density MoS₂ nanoflowers were synthesized using simple chemical vapor deposition with relatively low purity precursors and minimal growth time on a variety of substrates.  The effect of different temperature profiles, pressure, atmospheric composition, flow rate, precursor ratios, and substrate effects were studied. The samples were characterized via FSEM, Raman, EDS, Auger Electron Spectroscopy, and XDS. Low furnace ramp rates up to relatively high temperatures produced the densest growth. The grown MoS₂nanoflowers show potential as promising surfaces for HER catalysis, electrodes, and hydrophobic coatings.