Highly selective and reversible NO₂ gas sensor using vertically aligned MoS₂ flake networks

Abstract

We demonstrate a highly selective and reversible NO resistive gas sensor using vertically aligned MoS (VA-MoS) flake networks. We synthesized horizontally and vertically aligned MoS flakes on SiO/Si substrate using a kinetically controlled rapid growth CVD process. Uniformly interconnected MoS flakes and their orientation were confirmed by scanning electron microscopy, x-ray diffraction, Raman spectroscopy and x-ray photoelectron spectroscopy. The VA-MoS gas sensor showed two times higher response to NO compared to horizontally aligned MoS at room temperature. Moreover, the sensors exhibited a dramatically improved complete recovery upon NO exposure at its low optimum operating temperatures (100 °C). In addition, the sensing performance of the sensors was investigated with exposure to various gases such as NH, CO, H, CH and HS. It was observed that high response to gas directly correlates with the strong interaction of gas molecules on edge sites of the VA-MoS. The VA-MoS gas sensor exhibited high response with good reversibility and selectivity towards NO as a result of the high aspect ratio as well as high adsorption energy on exposed edge sites.

Controlled synthesis of ultrathin MoS2nanoflowers for highly enhanced NO2sensing at room temperature

“…This result can be explained by the stronger electronic interaction of NO 2 gas with MoS 2 owing to the higher adsorption energy of NO 2 on the active sites of the MoS 2 nanoowers compared with the other tested gases. 16,17 This result is consistent with previous theoretical calculations on the adsorption energy of various gases on MoS 2 materials. 54 The sensors based on the MoS 2 -48 h sample have good selectivity.…”

“…[13][14][15] Using the same method, Kumar et al synthesised nanostructures of vertically aligned MoS 2 akes and nanowire networks. 16,17 A previous study also formed MoS 2 nanoakes through sonication-assisted exfoliation. 9 Several 3D MoS 2 nanostructures, such as spheres and nanosheets, were synthesised using a hydrothermal approach, [18][19][20] which is a simple and low-cost mass-production synthesis method with growth parameters that can be easily controlled.…”

Effect of Flower‐Like and Spherical Nanostructured MoS2 on the Adsorption Properties of Cr(VI) Ions

“…For the Mo 3d spectra (Figure (b)), two distinct peaks at 228.5 eV and 231.7 eV correspond to the Mo 3d5/2 and Mo 3d3/2, respectively, indicating the characteristic of Mo 4+ state in MoS 2 . The peaks of S 2p3/2 and S 2p1/2 were located at 161.2 eV and 162.4 eV with a spin‐orbit splitting of 1.2 eV, revealing the S 2− in MoS 2 . This result further proves that the high purity MoS 2 was successfully prepared by hydrothermal method.…”

Gas Sensors Based on Mechanically Exfoliated MoS2 Nanosheets for Room-Temperature NO2 Detection

“…After removing the NO 2 from the gas sensor, the resistance of the gas sensor can return completely each time with almost no drift. The recovery behavior is very fast and recovery time constants are as short as 2–4 s. As the MoS 2 gas sensors reported in the previous works often fail to recover [28,29,30], the degree of recovery is an important indicator of the quality of the gas sensor. Herein, the recovery characteristic of the MoS 2 gas sensor is investigated by calculating the recovery rate, defined as follows [31,32].…”