Improved Gas Sensing Capabilities of MoS₂/Diamond Heterostructures at Room Temperature

Abstract

Molybdenum disulfide (MoS 2 ) and nanocrystalline diamond (NCD) have attracted considerable attention due to their unique electronic structure and extraordinary physical and chemical properties in many applications, including sensor devices in gas sensing applications. Combining MoS 2 and H-terminated NCD (H-NCD) in a heterostructure design can improve the sensing performance due to their mutual advantages. In this study, the synthesis of MoS 2 and H-NCD thin films using appropriate physical/ chemical deposition methods and their analysis in terms of gas sensing properties in their individual and combined forms are demonstrated. The sensitivity and time domain characteristics of the sensors were investigated for three gases: oxidizing NO 2 , reducing NH 3 , and neutral synthetic air. It was observed that the MoS 2 /H-NCD heterostructure-based gas sensor exhibits improved sensitivity to oxidizing NO 2 (0.157%•ppm −1 ) and reducing NH 3 (0.188%•ppm −1 ) gases compared to pure active materials (pure MoS 2 achieves responses of 0.018%•ppm −1 for NO 2 and −0.0072%•ppm −1 for NH 3 , respectively, and almost no response for pure H-NCD at room temperature). Different gas interaction model pathways were developed to describe the current flow mechanism through the sensing area with/without the heterostructure. The gas interaction model independently considers the influence of each material (chemisorption for MoS 2 and surface doping mechanism for H-NCD) as well as the current flow mechanism through the formed P−N heterojunction.

Resistive gas sensors for the detection of NH3 gas based on 2D WS2, WSe2, MoS2, and MoSe2: a review

“…When compared to pure MoS 2 and pure H-NCD at RT, the heterostructured sensor responded better to oxidizing NO 2 (0.157%•ppm-1) and reducing NH 3 (0.188%•ppm-1) gases. The development of p-n heterojunctions between the two materials at the interface was the cause of this increased response [117].…”

Gas sensors based on diamond heterostructures for air quality monitoring

“…The Mo layer was annealed in sulfur vapors at a high temperature of 800 °C in an N2 atmosphere at ambient pressure. The substrate was placed together with the sulfur powder in the center of the furnace so that the temperature of the substrate and the powder were the same during the growth, unlike the standard CVD method, which uses a two-zone furnace with different temperatures for the sulfur powder and the Mo substrate [14].…”

“…The first layer is, in most cases, H-NCD and the second material is prepared on it. The prepared heterostructures were kept for a week to stabilize the sensor surface [14,15].…”

Development of Dual-Selective Chemiresistive Sensor for NH3 and NOx at Room Temperature Using MoS2/MoO2 Heterostructures

“…In particular, MoS 2 is the extensively studied gas sensing TMD material because of its inherent defect sites, thickness-dependent variable bandgap, layered structure, and large active surface area . However, achieving a higher sensing response is challenging due to the weak interaction between TMDs’ surface and gas molecules. , The higher sensitivity of TMDs is accomplished by defect engineering, decorating metal nanoparticles, and heterostructure fabrication. The simplest of these techniques is the fabrication of the heterostructure.…”