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Here, we report on the synthesis of MoS2 nanosheets using a simple two-step additive-free growth technique. The as-synthesized nanosheets were characterized to determine their structure and composition, as well as their optical properties. The MoS2 nanosheets were analyzed by scanning electron microscopy, transmission electron microscopy (TEM), including high-resolution scanning TEM imaging and energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy (XPS), Raman spectroscopy and photoluminescence (PL). The as-produced MoS2 nanosheets are vertically aligned with curved edges and are densely populated. The TEM measurements confirmed that the nanosheets have the 2H-MoS2 crystal structure in agreement with the Raman results. The XPS results revealed the presence of high purity MoS2. Moreover, a prominent PL similar to mechanically exfoliated few and mono-layer MoS2 was observed for the as-grown nanosheets. For the thin (≤50 nm) nanosheets, the PL feature was observed at the same energy as that for a direct band-gap monolayer MoS2 (1.83 eV). Thus, the as-produced high-quality, large-area, MoS2 nanosheets could be potentially useful for various optoelectronic and catalysis applications.

Hexagonal‐shaped nanoplates (HNPs) of MoS2 on vertically aligned carbon nanotubes (CNTs) over a patterned area (a circular area of 1 cm2 diameter) are produced by chemical vapor deposition technique. With an optimized initial Mo film thickness, a uniform coverage of MoS2 HNPs with a thickness around 20 nm is achieved. The results confirm that the CNT template plays an important role in the MoS2 HNPs growth. Each MoS2 HNP consists of abundant exposed edges, interesting for sensing and catalysis applications. High crystallinity and quality of the as‐produced material are revealed by X‐ray photoelectron and Raman spectroscopies. Furthermore, NO2 gas‐sensing studies show better sensitivity and recovery for MoS2/CNT samples as compared to pristine CNTs. The detection of NO2 gas in a few tens of parts per million to a few hundreds of parts per billion range, at room temperature, is achieved. Density‐functional theory calculation indicates that the exposed edges of MoS2 play a significant role in the NO2 sensing as compared to horizontally aligned MoS2 layers. The present report can promote the research toward the fabrication of efficient and reliable MoS2‐based hybrid materials for toxic gas‐sensing applications for air quality monitoring in various environments.