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Highly Sensitive and Selective Defect WS₂ Chemical Sensor for Detecting HCHO Toxic Gases

by Zhen Cui, Hanxiao Wang, Kunqi Yang, Yang Shen, Ke Qin, Pei Yuan and Enling Li

Sensors 2024, 24(3), 762; https://doi.org/10.3390/s24030762 - 24 Jan 2024

Cited by 44 | Viewed by 2857

The gas sensitivity of the W defect in WS₂ (V_W/WS₂) to five toxic gases—HCHO, CH₄, CH₃HO, CH₃OH, and CH₃CH₃—has been examined in this article. These five gases were [...] Read more.

The gas sensitivity of the W defect in WS₂ (V_W/WS₂) to five toxic gases—HCHO, CH₄, CH₃HO, CH₃OH, and CH₃CH₃—has been examined in this article. These five gases were adsorbed on the V_W/WS₂ surface, and the band, density of state (DOS), charge density difference (CDD), work function (W), current–voltage (I–V) characteristic, and sensitivity of adsorption systems were determined. Interestingly, for HCHO-V_W/WS₂, the energy level contribution of HCHO is closer to the Fermi level, the charge transfer (B) is the largest (0.104 e), the increase in W is more obvious than other adsorption systems, the slope of the I–V characteristic changes more obviously, and the calculated sensitivity is the highest. To sum up, V_W/WS₂ is more sensitive to HCHO. In conclusion, V_W/WS₂ has a great deal of promise for producing HCHO chemical sensors due to its high sensitivity and selectivity for HCHO, which can aid in the precise and efficient detection of toxic gases. Full article

(This article belongs to the Special Issue Chemical Sensors for Toxic Chemical Detection)

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17 pages, 4297 KB

Open AccessArticle

Hydrogen Sensing Mechanism of WS₂ Gas Sensors Analyzed with DFT and NAP-XPS

by Tomoya Minezaki, Peter Krüger, Fatima Ezahra Annanouch, Juan Casanova-Cháfer, Aanchal Alagh, Ignacio J. Villar-Garcia, Virginia Pérez-Dieste, Eduard Llobet and Carla Bittencourt

Sensors 2023, 23(10), 4623; https://doi.org/10.3390/s23104623 - 10 May 2023

Cited by 19 | Viewed by 4821

Abstract

Nanostructured tungsten disulfide (WS₂) is one of the most promising candidates for being used as active nanomaterial in chemiresistive gas sensors, as it responds to hydrogen gas at room temperature. This study analyzes the hydrogen sensing mechanism of a nanostructured WS₂ layer using near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) and density functional theory (DFT). The W 4f and S 2p NAP-XPS spectra suggest that hydrogen makes physisorption on the WS₂ active surface at room temperature and chemisorption on tungsten atoms at temperatures above 150 °C. DFT calculations show that a hydrogen molecule physically adsorbs on the defect-free WS₂ monolayer, while it splits and makes chemical bonds with the nearest tungsten atoms on the sulfur point defect. The hydrogen adsorption on the sulfur defect causes a large charge transfer from the WS₂ monolayer to the adsorbed hydrogen. In addition, it decreases the intensity of the in-gap state, which is generated by the sulfur point defect. Furthermore, the calculations explain the increase in the resistance of the gas sensor when hydrogen interacts with the WS₂ active layer. Full article

(This article belongs to the Section Chemical Sensors)

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