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- Title
Hydrogen Sensing Mechanism of WS 2 Gas Sensors Analyzed with DFT and NAP-XPS.
- Authors
Minezaki, Tomoya; Krüger, Peter; Annanouch, Fatima Ezahra; Casanova-Cháfer, Juan; Alagh, Aanchal; Villar-Garcia, Ignacio J.; Pérez-Dieste, Virginia; Llobet, Eduard; Bittencourt, Carla
- 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.
- Subjects
GAS detectors; CHEMICAL bonds; HYDROGEN; DENSITY functional theory; POINT defects; CHARGE transfer
- Publication
Sensors (14248220), 2023, Vol 23, Issue 10, p4623
- ISSN
1424-8220
- Publication type
Article
- DOI
10.3390/s23104623