MoS2–carbon nanotube hybrid material growth and gas sensing

Abstract

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.

Patterned 3D hierarchical MoS₂ hexagonal nanoplates with exposed edges are synthesized on vertically aligned carbon nanotubes by a simple chemical vapor deposition technique. The as-grown hybrid heterostructure with only top contacts, shows excellent NO₂ gas-sensing properties over a few ppb to a few hundreds of ppm range.