Density Functional Theory Analysis of Gas Adsorption on Monolayer and Few Layer Transition Metal Dichalcogenides: Implications for Sensing

Babar, Vasudeo Pandurang; Vovusha, Hakkim; Schwingenschlögl, Udo

doi:10.1021/acsanm.9b01642

Cited by 63 publications

(56 citation statements)

References 37 publications

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“…Moreover, among the four considered configurations, NH 3 adsorbed on the ‘O-top-ii MoO 3 surface’ having the lowest E ads (−0.344 eV) reflects that the NH 3 molecule is physically adsorbed (−33.191 kJ mol –1 ) on the MoS 2 /MoO 3 surface. Furthermore, it has been seen that the interaction of the NH 3 molecule with the MoS 2 /MoO 3 surface is stronger than that with the MoSe 2 surface, monolayer and bilayer MoS 2 and WS 2 surfaces, and the MoS 2 /WS 2 hetero-bilayer surface but weaker than that with the MoS 2 /WO 3 surface . Next, to investigate the sensitivity of the NH 3 molecule on the MoS 2 /MoO 3 surface, band structure analysis has been performed.…”

Section: Resultsmentioning

confidence: 99%

MoS₂/MoO₃ Nanocomposite for Selective NH₃ Detection in a Humid Environment

Singh

Deb

Sarkar

et al. 2021

ACS Sustainable Chem. Eng.

113

110

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Designing a material with novel sensing properties under extreme working conditions has remained a challenging task. Here, we report a facile two-step approach to develop a MoS 2 /MoO 3 composite with enhanced surface properties. When used as a gas sensor at 25 °C, it displayed superior sensing properties, selectivity, and a stable response toward ammonia against various reducing and oxidizing gases under highly humid conditions (relative humidity ≈ 95%). The composite exhibited a relative response of ≈55% (15% for 1 ppm) toward 50 ppm of NH 3 with smaller response τ res. and recovery τ rev. times of 45 and 53 s, respectively. It also displayed complete recovery without any external optical or thermal stimulus. The enhanced sensing properties of the composite are attributed to the synergistic effect arising from heterostructure formation between two base materials. The sensor displayed a decrease in resistance when exposed to NH 3 , a reducing gas, thus indicating its n-type character, which was further confirmed by performing Mott−Schottky (MS) measurements on MoS 2 and the MoS 2 /MoO 3 composite, both displaying n-type behavior with increased electron densities of the composite. Further, to understand the adsorption process and the resulting sensing properties, density functional theory simulations were performed using a pristine and a defect-enriched MoS 2 /MoO 3 surface. Large negative adsorption energies (for NH 3 ) of −344 and −519 meV, respectively, reflect that the adsorption process is feasible, and mechanism change from physisorption to chemisorption is predicted. Bader scheme was employed to evaluate the charge transfer between the NH 3 molecule and the pristine (defect-enriched) MoS 2 /MoO 3 surface and gave an amount of 0.073e (0.010e). Therefore, these results collectively justify the use of the MoS 2 /MoO 3 composite as a selective NH 3 sensor that can operate in humid air and environmental monitoring applications where such conditions exist.

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Section: Resultsmentioning

confidence: 99%

MoS₂/MoO₃ Nanocomposite for Selective NH₃ Detection in a Humid Environment

Singh

Deb

Sarkar

et al. 2021

ACS Sustainable Chem. Eng.

113

110

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“…Tables and summarize previous results for the adsorption of representative small molecules (NO 2 , an electron acceptor, − and NH 3 , an electron donor ,,− ,, ) on an isolated monolayer of MoS 2 that is free of strain and defects. Although such a system may be viewed as idealized, it is a necessary first step in studying more complex issues such as the effects of supporting underlayers.…”

Section: Introductionmentioning

confidence: 85%

Computational Study of the Adsorption of NO₂ on Monolayer MoS₂

Bermudez

2020

J. Phys. Chem. C

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The potential energy surface for NO 2 physisorbed on a MoS 2 monolayer, acting as a chemical sensor, is complex with several configurations having similar adsorption energies (ΔE ads ) and charge-transfer characteristics. Hence, this can be considered to be a difficult system to model. A careful exploration of the energy surface is necessary in order to identify any sites at which strong adsorption and/or enhanced charge transfer can occur, which would affect sensor operation. Beyond this, a general computational approach is needed that can efficiently identify the lowest-energy configuration for a molecule weakly adsorbed on MoS 2 since this pertains to many potential sensor applications. In the present study, the computational methods are first carefully tested. Then ab initio molecular dynamics simulations are employed for an unbiased sampling of configuration space, which makes use of the approximate correlation between increasing ΔE ads and decreasing NO 2 -MoS 2 separation. A simulation temperature of ∼225 K, which promotes surface diffusion of NO 2 but not rapid desorption, appears to be nearly ideal. A series of simulations identified several transient configurations with relatively small separations, and each of these was evaluated and compared with previously reported adsorption models. A well-defined structure with the highest ΔE ads is thus identified and characterized, and further insight into adsorption and surface structure is obtained by computing the charge density at the valence band maximum and the effects of NO 2 on charge density. These results were extended to a preliminary investigation of the intercalation of NO 2 between MoS 2 layers. This is found to be energetically unfavorable and to destabilize a 2H MoS 2 bilayer at 300 K. However, when relaxed at 0 K, intercalated NO 2 is seen to affect the layer stacking and to increase the charge transfer relative to adsorption on a monolayer. The implications of these results for sensor applications are briefly discussed.

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“…Due to their large surface area, graphene, [ 23–25 ] other 2D materials [ 26–28 ] , and transition metal dichalcogenides [ 29–33 ] are widely explored both experimentally and theoretically for utilization in gas‐sensing devices. MXenes are also promising for sensing applications due to the important facts that i) MXenes have a large surface to volume ratio which helps to provide stable binding properties upon gas adsorption, ii) the metallic or semi‐metallic characteristics of MXenes ensures a superior charge transfer which is essential for the working of sensors, and iii) they have a superior signal‐to‐noise ratio which can be efficiently used for the detection of very small concentrations of air‐pollutants.…”

Section: Introductionmentioning

confidence: 99%

Phosgene Gas Sensing of Ti₂CT₂ (T = F⁻, O⁻, OH⁻) MXenes

Thomas

Zaeem

2021

Advcd Theory and Sims

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The phosgene gas sensing properties of experimentally produced 2D titanium carbide MXenes with surface terminations (Ti2CT2: T = F−, O−, OH−) are studied by first‐principles calculations. The effect of Ti and C vacancy defects, which are frequently created in synthesizing MXenes, on the structural, mechanical, electronic, and gas adsorption properties are studied to analyze the phosgene gas sensing performance of Ti2CT2 MXenes. Pristine and defective Ti2C, Ti2CF2, and Ti2C(OH)2 show metallicity, making them ideal for gas sensing. Ti (C) vacancy defects in Ti2CO2, Ti2CF2, and Ti2C(OH)2 cause an increase (decrease) in work function, resulting in enhanced interaction between the MXene surface and a gas molecule. When a phosgene gas molecule is exposed on the surface of MXenes, only Ti2C(OH)2 shows stable adsorption and charge transfer. An ultra‐low recovery time, the time between adsorption and desorption of a phosgene gas molecule, is achieved for both pristine and defective Ti2C(OH)2 with Ti vacancy. The results elucidate that a Ti2C(OH)2 based sensor has a high potential for efficient reversible phosgene detection.

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Density Functional Theory Analysis of Gas Adsorption on Monolayer and Few Layer Transition Metal Dichalcogenides: Implications for Sensing

Cited by 63 publications

References 37 publications

MoS₂/MoO₃ Nanocomposite for Selective NH₃ Detection in a Humid Environment

MoS₂/MoO₃ Nanocomposite for Selective NH₃ Detection in a Humid Environment

Computational Study of the Adsorption of NO₂ on Monolayer MoS₂

Phosgene Gas Sensing of Ti₂CT₂ (T = F⁻, O⁻, OH⁻) MXenes

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Density Functional Theory Analysis of Gas Adsorption on Monolayer and Few Layer Transition Metal Dichalcogenides: Implications for Sensing

Cited by 63 publications

References 37 publications

MoS2/MoO3 Nanocomposite for Selective NH3 Detection in a Humid Environment

MoS2/MoO3 Nanocomposite for Selective NH3 Detection in a Humid Environment

Computational Study of the Adsorption of NO2 on Monolayer MoS2

Phosgene Gas Sensing of Ti2CT2 (T = F−, O−, OH−) MXenes

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Product

Resources

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MoS₂/MoO₃ Nanocomposite for Selective NH₃ Detection in a Humid Environment

MoS₂/MoO₃ Nanocomposite for Selective NH₃ Detection in a Humid Environment

Computational Study of the Adsorption of NO₂ on Monolayer MoS₂

Phosgene Gas Sensing of Ti₂CT₂ (T = F⁻, O⁻, OH⁻) MXenes