| 1. |
- Bhojani, Amit K., et al.
(författare)
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Carbon-based monochalcogenides for efficient solar and heat energy harvesting
- 2023
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 608
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Tidskriftsartikel (refereegranskat)abstract
- A new generation of two-dimensional (2D) material has captivated significant attention in the energy conversion field owing to their promising optoelectronics and thermoelectric applications. The present work involves the systematic investigation of fundamental properties of single-layered 2D carbon-based monochalcogenides (CS, CSe, CTe) with planar, buckled and puckered geometry within the framework of density functional theory (DFT). The structural and lattice dynamics analysis disclose that puckered and buckled configurations are energetically and dynamically stable whereas planar structures depict instability. The anisotropic group velocity of longitu-dinal acoustic (LA) and transverse acoustic (TA) phonon modes in puckered systems may render the charac-teristics thermal transport properties. Additionally, for the first time, we scrutinized the thermoelectric and optical properties of these materials. At room temperature, the electron carrier mobilities are 174.698 and 160.830 m(2)V(-1)s(-1) of puckered and buckled CS systems, respectively are highest among all structures. The computed Seebeck coefficient, electrical conductivity and power factor manifests the high thermoelectric transport properties of puckered CS material. Further, the calculated solar parameters demonstrate an excep-tionally high-power conversion efficiency of 19.61 % for puckered CTe. Present work indicates that puckered phase of CS and CTe show their potential for the heat and solar energy harvesting devices, respectively.
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| 2. |
- Haman, Zakaryae, et al.
(författare)
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Computational identification of efficient 2D Aluminium chalcogenides monolayers for optoelectronics and photocatalysts applications
- 2021
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 556
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Tidskriftsartikel (refereegranskat)abstract
- The massive consumption of traditional fossil fuel like oil, coal and natural gas has led to serious environmental issues, which drove the search for cleaner renewable energy sources. One such option is photocatalytic water splitting that has attracted much attention as a viable process for the large scale production of hydrogen as a renewable fuel. Within this perspective, we methodically studied the structural, optoelectronic, and photocatalytic properties of two-dimensional aluminum monochalcogenide monolayers with the chemical formula AlX (X = O, S, Se, and Te) based on the framework of Density Functional Theory (DFT). All considered structures are full relaxed and their thermodynamic stabilities are confirmed by computing the phonon spectrum and Ab Initio Molecular Dynamics (AIMD) simulations. The electronic characteristics are also performed on the basis of both exchange correlation functional GGA-PBE and HSE06 in order to obtain the accurate electronic band gap. According to our calculations, all the four monolayers posses indirect band gaps ranging between 1.937 and 2.46 eV. Furthermore, based on desirable electronic band gaps, the optical performance features were further explored including complex refractive index, absorption coefficient and energy loss function by means of the complex dielectric function. It is found that all the four materials present a high absorption coefficient in the visible and Ultra-Violet regions. Finally, the band edge positions of our monolayers straddle the reduction potential of H2 and the oxidation potential H2O. Also, it was found that the Gibbs free energy of 2D AlO monolayer is 0.02 eV at certain applied external electric field and very close to ideal catalysts which suggest that the AlO monolayer is better candidate for hydrogen production. Our findings demonstrate that AlX monolayers are suitable materials for optoelectronics and hydrogen production via photocatalytic water splitting.
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| 3. |
- Haman, Zakaryae, et al.
(författare)
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Janus Aluminum Oxysulfide Al2OS : A promising 2D direct semiconductor photocatalyst with strong visible light harvesting
- 2022
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 589
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen production via solar light-driven water dissociation has been regarded as an artificial and effective process to overcome the environmental problem as well as solving the current energy crisis. In this regard, numerous works have mainly been devoted to developing the appropriate photocatalyst which satisfies the conditions for water splitting and understanding the photocatalysis process. In this study, we propose for the first time the potential application of the two-dimensional Janus aluminum oxysulfide Al2OS as an efficient photocatalyst material for hydrogen-production H-2 through the first-principles calculations. Janus Al2OS monolayer has been designed from the parental binary aluminum sulfide AlS by substituting one sub-layer of sulfide atoms (S) to oxygen atoms (O). The electronic properties of the pristine AlS and the derived Janus Al2OS were computed using GGA-PBE and HSE06 functionals. According to the band structure, AlS monolayer shows a semiconductor behavior with an indirect bandgap of 2.14 eV whereas, the Janus Al2OS exhibits a direct bandgap of 1.579 eV. Motivated by the desirable bandgap of the Janus Al2OS, the absorption-coefficient of Janus Al2OS shows strong visible light harvesting compared to the parental AlS. Furthermore, the photocatalytic performance of Al2OS has been investigated. Our calculations demonstrate that the band edge position of Al2OS is suitable for the hydrogen evolution reaction (HER). More importantly, based on the reaction coordinate, it was found that the Gibbs free-energy Delta G(H*) of Al2OS is 0.97 eV which is smaller than of the two-dimensional Janus Ga2XY (X, Y = S, Se, Te with X not equal Y) reported recently. Moreover, this value decreases from 0.97 eV to 0.69 eV under 0.5 V/angstrom of an external electrical field. Our results indicate that Janus Al2OS fulfills the fundamental requirements for efficient photo-catalyst under visible light and provides new guidance for hydrogen-production via water splitting.
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| 4. |
- Hussain, T., et al.
(författare)
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Efficient and selective sensing of nitrogen-containing gases by Si2BN nanosheets under pristine and pre-oxidized conditions
- 2019
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Ingår i: Applied Surface Science. - : ELSEVIER SCIENCE BV. - 0169-4332 .- 1873-5584. ; 469, s. 775-780
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Tidskriftsartikel (refereegranskat)abstract
- Motivated by the promise of two-dimensional nanostructures in the field of gas sensing, we have employed van der Waals corrected density functional theory calculations to study the structural, electronic and gas sensing propensities of the recently designed Si2BN monolayer. Our rigorous simulations reveal that the representative members of nitrogen-containing gases (NCGs) such as NO, NO2 and NH3 binds extremely strongly on pristine Si2BN monolayer. However, a strong dissociative adsorption in case of NO and NO2 would poison the Si2BN and ultimately reversibility of the monolayer would be compromised. Exploring the sensing mechanism in more realistic pre-oxidized conditions, the binding characteristics of O-2@Si2BN changed dramatically, resulting into much lower adsorption in associative manner for all NO, NO2 and NH3. A visible change in work function indicates the variation in conductivity of O-2@Si2BN upon the exposure of incident gases. Sustainable values of binding energies would also ensure a quick recovery time that makes O-2@Si2BN an efficient nano sensor for pollutants like NCGs.
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| 5. |
- Lakhani, Krupa, et al.
(författare)
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Dissociation of air pollutants on the uniform surface of pentagonal BeP2
- 2021
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 570
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Tidskriftsartikel (refereegranskat)abstract
- In this present work, the investigation was carried out using density functional theory (DFT) for the dissociation of noxious gas molecules such as carbon and nitrogen-based molecules (CO, CO2, N-2, NH3, NO, and NO2) on a pentagonal two-dimensional beryllium diphosphide (BeP2). The pentagonal BeP2 monolayer has a similar band structure as graphene. Here, some carbon and nitrogen-based noxious gases such as CO, CO2, N-2, NH3, NO, and NO2 with Van der Waals (vdW) interaction behave like physisorbed, while strong covalent (Be-O) interactions of O-2 on BeP2 formed chemisorption. Due to the chemisorption of O-2 gas molecules, the bandgap at Dirac point at P-site on BeP2 opens. While CO, CO2, N-2, NO, and NO2 are dissociated at the C-site, only CO, N-2, and NO are dissociated at the P-site. Beryllium diphosphide's band-gap shifts resulting from interactions with CO, N-2, and O-2 molecules are just 6%, 12.1%, and 22.2%, respectively, meaning that the BeP2 material has a moderate and high sensitivity towards CO, N-2, and O-2 molecules. BeP2 appears to be a potential catalyst for the dissociation of CO, CO2, N-2, NO, NO2, and O-2 gas molecules, which is even more interesting.
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| 6. |
- Majumdar, Arnab, et al.
(författare)
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High exothermic dissociation in van der Waals like hexagonal two dimensional nitrogene from first-principles molecular dynamics
- 2020
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 529
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Tidskriftsartikel (refereegranskat)abstract
- Mono and multilayered two dimensional (2D) nitrogene in which nitrogen atoms are single bonded are studied for energy applications. The structures are observed to be dynamically and thermally stable at room temperature but dissociate into triple bonded N-2 molecules at higher temperatures. From ab initio molecular dynamics simulations, the dissociation temperature is found to be decreasing with increasing number of layers (1500 K for single layer and 500 K for six layers). The energy released for the different layered cases is large due to the energy difference between single and triple-bonded nitrogen (similar to 0.88 - 1.8 eV/atom). Significantly high energy densities calculated for the multilayered structures (similar to 6 - 12.3 kJ/gm) can secure these materials an important position amongst non-nuclear and inorganic high energy density materials known today. We believe that this work will shed light on synthesizing next generation non-nuclear environmentally clean high energy density materials using multi-layer nitrogene that detonate at not very high temperatures.
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| 7. |
- Naqvi, Syeda R., et al.
(författare)
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Superior sensitivity of metal functionalized boron carbide (BC3) monolayer towards carbonaceous pollutants
- 2020
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 512
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Tidskriftsartikel (refereegranskat)abstract
- The sensitivity of light metal functionalized boron carbide (BC3) sheets towards selected carbonaceous gases like CO, CO2, and CH4 is investigated by using first principles density functional theory calculations. We find that functionalization with alkali (Li, Na, K) and alkaline earth metals (Be, Mg, Ca), is a useful strategy to improve the sensitivity of graphene-like BC3 towards the mentioned gases. A semiconductor-to-metal transformation of BC3 is observed upon the introduction of metal dopants. Gas molecules are adsorbed on the metallized BC3 through weak chemisorption, which is an ideal scenario for gas sensing under practical working conditions. We find that the adsorption energies (Eads) of CO molecule are found to be 1.71, 0.48, 0.34, 0.35, 0.96, and 0.84 eV on Be-, Li-, Na-, K-, Mg-, and Ca-doped BC3, respectively. Similarly, CO2 binds to Li-, Be-, Mg-, and Ca- doped BC3 with Eads of 0.54, 0.87, 0.61, and 0.43 eV, respectively. For CH4, an Eads value of 0.74 eV turns out to be the strongest in case of Be-BC3. Bader charge analysis divulges that the transfer of charges results in the adsorption mechanism of the gases to the metallized BC3. In addition to feasible Eads, change in the work function upon the adsorption of gas molecules further confirms good sensitivity of the metallized BC3 towards CO, CO2and CH4. Based on our findings, we deduce that metal-doped BC3 is an excellent candidate for the efficient sensing of harmful pollutants.
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| 8. |
- Ouyang, Tianhong, et al.
(författare)
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Effect of defects on adsorption characteristics of AlN monolayer towards SO2 and NO2 : Ab initio exposure
- 2018
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Ingår i: Applied Surface Science. - : ELSEVIER SCIENCE BV. - 0169-4332 .- 1873-5584. ; 462, s. 615-622
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Tidskriftsartikel (refereegranskat)abstract
- Density functional theory (DFT) calculations have been employed to explore the adsorption properties of pristine and vacancy-defective AlN monolayer towards SO2 and NO2 in terms of their adsorption energies and electronic structures. The calculations with van der Waals effect are performed to study the binding mechanism of pristine and vacancy-defective AlN nanosheet with SO2 and NO2. Three types of vacancy defects are considered including Al-monovacancy, N-monovacancy and divacancy. The adsorption energies of vacancy-defective AlN monolayer towards SO2 and NO2 are found to be much higher than that of pristine nanosheet. The equilibrium adsorption sites and configurations of the gas molecules on AlN nanosheets are determined. The Bader charge transfer analysis reveals that a considerable amount of charge is transferred from the vacancy-defective AlN nanosheets to the gases leading to the increase of adsorption energies. The results of difference charge densities, band structures, electronic density of states and work function further give insight into adsorption energies. The dramatical changes of electronic band structures after gas interaction suggest the excellent adsorption properties of vacancy-defective AlN monolayer towards SO2 and NO2.
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| 9. |
- Ouyang, Tianhong, et al.
(författare)
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First-principles investigation of CO adsorption on pristine, C-doped and N-vacancy defected hexagonal AlN nanosheets
- 2018
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 439, s. 196-201
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Tidskriftsartikel (refereegranskat)abstract
- The optimized atomic structures, energetics and electronic structures of toxic gas CO adsorption systems on pristine, C-doped and N-vacancy defected h-AlN nanosheets respectively have been investigated using Density functional theory (DFT-D2 method) to explore their potential gas detection or sensing capabilities. It is found that both the C-doping and the N-vacancy defect improve the CO adsorption energies of AlN nanosheet (from pure -3.847 eV to -5.192 eV and -4.959 eV). The absolute value of the system band gap change induced by adsorption of CO can be scaled up to 2.558 eV or 1.296 eV after C-doping or N-vacancy design respectively, which is evidently larger than the value of 0.350 eV for pristine material and will benefit the robustness of electronic signals in potential gas detection. Charge transfer mechanisms between CO and the AlN nanosheet have been presented by the Bader charge and differential charge density analysis to explore the deep origin of the underlying electronic structure changes. This theoretical study is proposed to predict and understand the CO adsorption properties of the pristine and defected h-AlN nanosheets and would help to guide experimentalists to develop better AlN-based two-dimensional materials for efficient gas detection or sensing applications in the future.
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| 10. |
- Panigrahi, Puspamitra, et al.
(författare)
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Application of germanene monolayers as efficient anchoring material to immobilize lithium polysulfides in Li-S batteries
- 2021
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 558
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Tidskriftsartikel (refereegranskat)abstract
- The Lithium-sulfur (Li-S) battery chemistries have so far been plagued with difficulties such as the dissolution of intermediate lithium-polysulfides (LPSs) into the electrolyte, the so-called shuttle-effect, causing the capacity loss. Using van der Waals corrected density functional theory approach, we report the outstanding anchoring effect of germanene monolayer (GeM), which can trap the LPSs sturdily without disturbing their integrity. The persistent electrical conductivity of GeM upon adsorption of LPSs demonstrates an effective strategy for the enhanced cyclic performance of Li-S batteries while avoiding the shuttling effect and preventing agglomeration at the battery electrodes. It is found that the LPSs adsorbed to GeM with a moderate assortment between -1.8. to -2.6 eV. In addition to the efficient anchoring performance, the electronic properties of GeM also improve upon the adsorption of LPSs. The diffusion barrier energies of LPSs are very small, thus ensuring their ultrafast diffusion and smooth transition during the charge/discharge process of the Li-S battery.
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