Growth and Tunable Surface Wettability of Vertical MoS₂ Layers for Improved Hydrogen Evolution Reactions

Abstract

Layered materials, especially the transition metal dichalcogenides (TMDs), are of interest for a broad range of applications. Among the class of TMDs, molybdenum disulfide (MoS2) is perhaps the most studied because of its natural abundance and use in optoelectronics, energy storage and energy conversion applications. Understanding the fundamental structure-property relations is key for tailoring the enhancement in the above-mentioned applications. Here, we report a controlled powder vaporization synthesis of MoS2 flower-like structures consisting of vertically grown layers of MoS2 exhibiting exposed edges. This growth is readily achievable on multiple substrates, such as graphite, silicon, and silicon dioxide. The resulting MoS2 flowers are highly crystalline and stoichiometric. Further observations using contact angle indicate that MoS2 flowers exhibit the highest reported contact angle of ∼160 ± 10°, making the material super hydrophobic. This surface wettability was further tuned by changing the edge chemistry of the MoS2 flowers using an ozone etching treatment. Hydrogen evolution reaction (HER) measurements indicate that the surface treated with UV-ozone showed a reduction in the Tafel slope from 185 to 54 mV/dec, suggesting an increase in the amount of reactive surface to generate hydrogen.

Growth of Large‐Area SnS Films with Oriented 2D SnS Layers for Energy‐Efficient Broadband Optoelectronics

“…Orientation control is often observed in the growth of sulfides under various reaction conditions. The formation of vertical layers of MoS 2 , WS 2 , and HfS 2 grown in the presence of adequate sulfur vapor has been described by the sulfurization approach. Inclined layers of SnS grown by pyrolysis of a solution containing Sn 2+ and S 2− with adequate sulfur vapor induces vertical growth .…”

Recent Progress on Irradiation-Induced Defect Engineering of Two-Dimensional 2H-MoS2 Few Layers

“…MoS 2 layers can be significantly activated, functionalized, and modified. The irradiation-induced defects are beneficial for several applications including: solar cells [19,[194][195][196], batteries [54,197,198], supercapacitors [199], thin film transistors [15,16,80,86,110,138,[200][201][202][203][204][205], sensors [17,55,56,106,[206][207][208][209][210], hydrogen generators [8,47,50,69,134,176,177,183,211,212], and applications in thermoelectrics [213][214][215][216], piezotronics [63], valleytronics [65], and environments [45,49]. MoS 2 2D layers were damaged simultaneously under ...…”

“…Bhimanapati et al [134] treated MoS 2 vertical layers in UV-ozone. The ozone treatment increased super wettability and enhanced hydrogen evolution reaction of the material by changing edge chemistry and surface defects.…”

Activating the MoS2 Basal Plane by Controllable Fabrication of Pores for an Enhanced Hydrogen Evolution Reaction

“…Ah ighly ordered double-gyroid MoS 2 bicontinuous network with nanoscaled pores andm ultiscale structural and electronic control of MoS 2 foam was fabricatedb yas ilica template method, which showed an excellent HER activity,o wing to the large fractiono fe dge sites exposed. [19,21] In addition, the defect-rich MoS 2 , [22] hollow MoS 2 macro/nanosphere, [23] vertically grown layers of MoS 2 , [24] MoS 2 /RGO hybrid materials, [25] and oxygen-incorporated MoS 2 [26] have been successfully synthesized to improveHER performance by exposing alarge fraction of edge sites. However,a ctivating the MoS 2 basal plane could furtherenhancei ts HER activity.…”