| 1. |
- Panigrahi, Puspamitra, et al.
(författare)
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Efficient Sensing of Selected Amino Acids as Biomarker by Green Phosphorene Monolayers : Smart Diagnosis of Viruses
- 2022
-
Ingår i: Advanced Theory and Simulations. - : John Wiley & Sons. - 2513-0390. ; 5:10
-
Tidskriftsartikel (refereegranskat)abstract
- Effective techniques for the detection of selected viruses detection of their amino acids (AAs) constituents are highly desired, especially in the present COVID pandemic. Motivated by this, we have used density functional theory (DFT) simulations to explore the potential applications of green phosphorene monolayer (GPM) as efficient nanobio-sensor. We have employed van der Waals induced calculations to study the ground-state geometries, binding strength, electronic structures, and charge transfer mechanism of pristine, vacancy-induced and metal-doped GPM to detect the selected AAs, such as glycine, proline and aspartic, in both aqueous and non-aqueous media. We find that the interactions of studied AAs are comparatively weak on pristine (-0.49 to -0.76 eV) and vacancy-induced GPM as compared to the metal-doped GPM (-0.62 to -1.22 eV). Among the considered dopants, Ag-doping enhances the binding of AAs to the GPM stronger than the others. In addition to appropriate binding energies, significant charge transfers coupled with measurable changes in the electronic properties further authenticate the potential of GPM. Boltzmann thermodynamic analysis have been used to study the sensing mechanism under varied conditions of temperatures and pressure for the practical applications. Our findings signify the potential of G PM based sensors towards efficient detection of the selected AAs.
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| 2. |
- Araujo, Rafael B., et al.
(författare)
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Assessing Electrochemical Properties of Polypyridine and Polythiophene for Prospective Application in Sustainable Organic Batteries
- 2017
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - 1463-9076 .- 1463-9084. ; 19:4, s. 3307-3314
-
Tidskriftsartikel (refereegranskat)abstract
- Conducting polymers are being considered promising candidates for sustainable organic batteries mainly due to their fast electron transport properties and high recyclability. In this work, key properties of polythiophene and polypyridine have been assessed through a combined theoretical and experimental study focusing on such applications. A theoretical protocol has been developed to calculate redox potentials in solution within the framework of the density functional theory and using continuous solvation models. Here, the evolution of the electrochemical properties of solvated oligomers as a function of the length of the chain is analyzed and then the polymer properties are estimated via linear regressions using ordinary least square. The predicted values were verified against our electrochemical experiments. This protocol can now be employed to screen a large database of compounds in order to identify organic electrodes with superior properties.
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| 3. |
- Araujo, Rafael B., et al.
(författare)
-
Assessing the electrochemical properties of polypyridine and polythiophene for prospective applications in sustainable organic batteries
- 2017
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 19:4, s. 3307-3314
-
Tidskriftsartikel (refereegranskat)abstract
- Conducting polymers are being considered promising candidates for sustainable organic batteries mainly due to their fast electron transport properties and high recyclability. In this work, the key properties of polythiophene and polypyridine have been assessed through a combined theoretical and experimental study focusing on such applications. A theoretical protocol has been developed to calculate redox potentials in solution within the framework of the density functional theory and using continuous solvation models. Here, the evolution of the electrochemical properties of solvated oligomers as a function of the length of the chain is analyzed and then the polymer properties are estimated via linear regressions using ordinary least square. The predicted values were verified against our electrochemical experiments. This protocol can now be employed to screen a large database of compounds in order to identify organic electrodes with superior properties.
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| 4. |
- Araujo, Rafael B., et al.
(författare)
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Designing strategies to tune reduction potential of organic molecules for sustainable high capacity batteries application
- 2017
-
Ingår i: Journal of Materials Chemistry A. - 2050-7488 .- 2050-7496. ; 5:9, s. 4430-4454
-
Tidskriftsartikel (refereegranskat)abstract
- Organic compounds evolve as a promising alternative to the currently used inorganic materials in rechargeable batteries due to their low-cost, environmentally friendliness and flexibility. One of the strategies to reach acceptable energy densities and to deal with the high solubility of known organic compounds is to combine small redox active molecules, acting as capacity carrying centres, with conducting polymers. Following this strategy, it is important to achieve redox matching between the chosen molecule and the polymer backbone. Here, a synergetic approach combining theory and experiment has been employed to investigate this strategy. The framework of density functional theory connected with the reaction field method has been applied to predict the formal potential of 137 molecules and identify promising candidates for the referent application. The effects of including different ring types, e.g. fused rings or bonded rings, heteroatoms, [small pi] bonds, as well as carboxyl groups on the formal potential, has been rationalized. Finally, we have identified a number of molecules with acceptable theoretical capacities that show redox matching with thiophene-based conducting polymers which, hence, are suggested as pendent groups for the development of conducting redox polymer based electrode materials.
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| 5. |
- Araujo, Rafael B., et al.
(författare)
-
Designing strategies to tune reduction potential of organic molecules for sustainable high capacity battery application
- 2017
-
Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 5:9, s. 4430-4454
-
Tidskriftsartikel (refereegranskat)abstract
- Organic compounds evolve as a promising alternative to currently used inorganic materials in rechargeable batteries due to their low-cost, environmental friendliness and flexibility. One of the strategies to reach acceptable energy densities and to deal with the high solubility of known organic compounds is to combine small redox active molecules, acting as capacity carrying centres, with conducting polymers. Following this strategy, it is important to achieve redox matching between the chosen molecule and the polymer backbone. Here, a synergetic approach combining theory and experiment has been employed to investigate this strategy. The framework of the density functional theory connected with the reaction field method has been applied to predict the formal potential of 137 molecules and identify promising candidates for the referent application. The effects of including different ring types, e.g. fused rings or bonded rings, heteroatoms, and pi bonds, as well as carboxyl groups on the formal potential, have been rationalized. Finally, we have identified a number of molecules with acceptable theoretical capacities that show redox matching with thiophene-based conducting polymers which, hence, are suggested as pendent groups for the development of conducting redox polymer based electrode materials.
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| 6. |
- Arslanov, Temirlan R., et al.
(författare)
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Pressure control of magnetic clusters in strongly inhomogeneous ferromagnetic chalcopyrites
- 2015
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 5, s. 7720-
-
Tidskriftsartikel (refereegranskat)abstract
- Room-temperature ferromagnetism in Mn-doped chalcopyrites is a desire aspect when applying those materials to spin electronics. However, dominance of high Curie-temperatures due to cluster formation or inhomogeneities limited their consideration. Here we report how an external perturbation such as applied hydrostatic pressure in CdGeP2:Mn induces a two serial magnetic transitions from ferromagnet to non-magnet state at room temperature. This effect is related to the unconventional properties of created MnP magnetic clusters within the host material. Such behavior is also discussed in connection with ab initio density functional calculations, where the structural properties of MnP indicate magnetic transitions as function of pressure as observed experimentally. Our results point out new ways to obtain controlled response of embedded magnetic clusters.
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| 7. |
- Hussain, Tanveer, et al.
(författare)
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Enriching physisorption of H2S and NH3 gases on a graphane sheet by doping with Li adatoms
- 2014
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 16:17, s. 8100-8105
-
Tidskriftsartikel (refereegranskat)abstract
- We have used density functional theory to investigate the adsorption efficiency of a hydrogenated graphene (graphane) sheet for H2S and NH3 gases. We find that neither the pristine graphane sheet nor the sheet defected by removing a few surface H atoms have sufficient affinity for either H2S or NH3 gas molecules. However, a graphane sheet doped with Li adatoms shows a strong sensing affinity for both the mentioned gas molecules. We have calculated the absorption energies with one [referred to as half coverage] molecule and two molecules [referred to as full coverage] for both gases with the Li-doped graphane sheet. We find that for both the gases, the calculated absorption energies are adequate enough to decide that the Li-doped graphane sheet is suitable for sensing H2S and NH3 gases. The Li-doped sheet shows a higher affinity for the NH3 gas compared to the H2S gas molecules due to a stronger Li(s)-N(p) hybridization compared to that of Li(s)-S(p). However, while going from the half coverage effect to the full coverage effect, the calculated binding energies show a decreasing trend for both the gases. The calculated work function of the Li-doped graphane sheet decreases while bringing the gas molecules within its vicinity, which explains the affinity of the sheet towards both the gas molecules.
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| 8. |
- Hussain, Tanveer, et al.
(författare)
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Hydrogen storage properties of light metal adatoms (Li, Na) decorated fluorographene monolayer
- 2015
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 26:27
-
Tidskriftsartikel (refereegranskat)abstract
- Owing to its high energy density, the potential of hydrogen (H-2) as an energy carrier has been immense, however its storage remains a big obstacle and calls for an efficient storage medium. By means of density functional theory (DFT) in spin polarized generalized gradient approximation (GGA), we have investigated the structural, electronic and hydrogen storage properties of a light alkali metal (Li, Na) functionalized fluorographene monolayer (FG). Metal adatoms bind to the FG with significantly high binding energy, much higher than their cohesive energies, which helps to achieve a uniform distribution of metal adatoms on the monolayer and consequently ensure reversibility. Due to a difference of electronegativities, each metal adatom transfers a substantial amount of its charge to the FG monolayer and attains a partial positive state, which facilitates the adsorption of multiple H-2 molecules around the adatoms by electrostatic as well as van der Waals interactions. To get a better description of H-2 adsorption energies with metal-doped systems, we have also performed calculations using van der Waals corrections. For both the functionalized systems, the results indicate a reasonably high H-2 storage capacity with H2 adsorption energies falling into the range for the practical applications.
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| 9. |
- Hussain, Tanveer, et al.
(författare)
-
Sensing propensity of a defected graphane sheet towards CO, H2O and NO2
- 2014
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 25:32, s. 325501-
-
Tidskriftsartikel (refereegranskat)abstract
- We have used density functional theory to investigate the sensing property of a hydrogenated graphene sheet (graphane) towards CO, H2O and NO2 gas molecules. Though the pristine graphane sheet is found not to have sufficient affinity towards the mentioned gas molecules, the defected sheet (removing few surface H atoms) has a strong affinity towards the gas molecules. While CO and H2O are found to be weakly physisorbed, the NO2 molecules are found to be strongly chemi-sorbed to the defected graphane sheet. With NO2, the N(p) and O(p) states are found to have strong hybridization with the most active C(p) states which lie at the defected site of the graphane sheet. While increasing the coverage effect of the mentioned gas molecules toward the defected sheet, the adsorption energies do not change significantly. At the same time, the work function of the defected graphane sheet shows an increasing trend while adsorbed with CO, H2O and NO2 gas molecules, opening up the possibilities for a future gas sensor.
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| 10. |
- Ian, Jason J., et al.
(författare)
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Superalkali functionalized two-dimensional haeckelite monolayers : A novel hydrogen storage architecture
- 2022
-
Ingår i: International journal of hydrogen energy. - : Elsevier. - 0360-3199 .- 1879-3487. ; 47:78, s. 33391-33402
-
Tidskriftsartikel (refereegranskat)abstract
- Exploring efficient storage mediums is the key challenge to accomplish a sustainable hydrogen economy. Material-based hydrogen (H-2) storage is safe, economically viable and possesses high gravimetric density. Here, we have designed a novel H-2 storage architecture by decorating graphene-like haeckelite (r57) sheets with the super-alkali (NLi4) clusters, which bonded strongly with the r57. We have performed van der Waals corrected density functional theory (DFT) calculations to study the structural, electronic, energetic, charge transfer, and H-2 storage properties of one-sided (r57-NLi4) and two-sided (r57-2NLi(4)) coverage of r57 sheets. Exceptionally high H-2 storage capacities of 10.74%, and 17.01% have been achieved for r57-NLi4, and r57-2NLi(4) systems, respectively that comfortably surpass the U.S. Department of Energy's (DOE) targets. Under maximum hydrogenation, the average H-2 adsorption energies have been found as -0.32 eV/H-2, which is ideal for reversible H-2 storage applications. We have further studied the effects of mechanical strain to explore the H-2 desorption mechanism. Statistical thermodynamic analysis has been employed to study the H-2 storage mechanism at varied conditions of pressures and temperatures. Our findings validate the potential of r57-xNLi(4) as efficient H-2 storage materials.
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| 11. |
- Kaewmaraya, Thanayut, et al.
(författare)
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A new, layered monoclinic phase of Co3O4 at high pressure
- 2015
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 17:30, s. 19957-19961
-
Tidskriftsartikel (refereegranskat)abstract
- We present the crystal structures and electronic properties of a Co3O4 spinel under high pressure. Co3O4 undergoes a first-order transition from a cubic (CB) Fd (3) over barm to a lower-symmetry monoclinic (MC) P2(1)/c phase at 35 GPa, occurring after the local high-spin to low-spin phase transition. The high-pressure phase exhibits the octahedral coordination of Co(II) and Co(III), whereas the CB phase contains the fourfold coordination of Co(II) and the sixfold coordination of Co(III). The CB-to-MC transition is attributed to the charge-transfer between the di-and trivalent cations via the enhanced 3d-3d interactions.
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| 12. |
- 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
-
Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 558
-
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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| 13. |
- Panigrahi, Puspamitra, et al.
(författare)
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Capacity enhancement of polylithiated functionalized boron nitride nanotubes : an efficient hydrogen storage medium
- 2020
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : ROYAL SOC CHEMISTRY. - 1463-9076 .- 1463-9084. ; 22:27, s. 15675-15682
-
Tidskriftsartikel (refereegranskat)abstract
- By using first principles density functional theory simulations, we report detailed geometries, electronic structures and hydrogen (H-2) storage properties of boron nitride nanotubes (BNNTs) doped with selective polylithiated molecules (CLi2). We find that unsaturated bonding of Li-1s states with BNNT significantly enhances the system stability and hinders the Li-Li clustering effect, which can be detrimental for reversible H(2)storage. The H(2)adsorption mechanism is explained on the basis of polarization caused by the cationic Li(+)of CLi(2)molecules bonded with BNNT. The incident H(2)molecules are adsorbed with BNNT-nCLi(2)through electrostatic and van der Waals interactions. We find that with a maximum of 5.0% of CLi(2)coverage on BNNT, an H(2)gravimetric density of up to 4.41 wt% can be achieved with adsorption energies in the range of -0.33 eV per H-2, which is suitable for ambient condition H(2)storage applications.
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| 14. |
- Panigrahi, Puspamitra, et al.
(författare)
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Crafting ferromagnetism in Mn-doped MgO surfaces with p-type defects
- 2014
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Ingår i: Science and Technology of Advanced Materials. - : Informa UK Limited. - 1468-6996 .- 1878-5514. ; 15:3, s. 035008-
-
Tidskriftsartikel (refereegranskat)abstract
- We have employed first-principles calculations based on density functional theory (DFT) to investigate the underlying physics of unusual magnetism in Mn-doped MgO surface. We have studied two distinct scenarios. In the first one, two Mn atoms are substitutionally added to the surface, occupying the Mg sites. Both are stabilized in the Mn3+ valence state carrying a local moment of 4.3 mu(B) having a high-spin configuration. The magnetic interaction between the local moments display a very short-ranged characteristic, decaying very quickly with distance, and having antiferromagnetic ordering lower in energy. The energetics analysis also indicates that the Mn ions prefer to stay close to each other with an oxygen atom bridging the local interaction. In the second scenario, we started exploring the effect of native defects on the magnetism by crafting both Mg and O vacancies, which are p-and n-type defects, respectively. It is found that the electrons and holes affect the magnetic interaction between Mn ions in a totally different manner. The n-type defect leads to very similar magnetism, with the AFM configuration being energetically preferred. However, in the presence of Mg vacancy, the situation is quite different. The Mn atoms are further oxidized, giving rise to mixed Mn(d) ionic states. As a consequence, the Mn atoms couple ferromagnetically, when placed in the close configuration, and the obtained electronic structure is coherent with the double-exchange type of magnetic interaction. To guarantee the robustness of our results, we have benchmarked our calculations with three distinct theory levels, namely DFT-GGA, DFT-GGA+U and DFT-hybrid functionals. On the surface, the Mg vacancy displays lower formation energy occurring at higher concentrations. Therefore, our model systems can be the basis to explain a number of controversial results regarding transition metal doped oxides.
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| 15. |
- Panigrahi, Puspamitra, et al.
(författare)
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Density Functional Theory Studies of Si2BN Nanosheets as Anode Materials for Magnesium-Ion Batteries
- 2020
-
Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970 .- 1944-8244 .- 1944-8252. ; 3:9, s. 9055-9063
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Tidskriftsartikel (refereegranskat)abstract
- The unique structural characteristics make the 2D materials potential candidates for designing negative electrodes for rechargeable energy storage devices. Here, by employing density functional theory (DFT) calculations, we study the precise viability of using Si2BN, a graphene-like 2D material, as a high-capacity anode material for Mg-ion battery (MIB) application. The favorable Mg-adsorption sites with maximum possible coverage effect are explored in detail. It is found that the Si2BN sheet can be adsorbed to a configuration of Mg8Si16B8N8, which proposes a theoretical capacity of 647.896 mA h g(-1) for divalent Mg2+-ion battery applications. The average open-circuit voltage of 0.6-0.7 V and intercalation migration energy barrier in the range of 0.08-0.35 eV make Si2BN one of the most promising anode materials for MIB applications. The porous Si2BN with high structural stability and metallic electronic structures along with the low Mg2+-ion migration barrier energies predict high electron and Mg-ion conductivity, ensuring fast charge/discharge cyclic performance. The above-mentioned findings validate that the Si2BN sheet can work as an excellent high-performance anode material for MIBs.
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| 16. |
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| 17. |
- Panigrahi, Puspamitra, et al.
(författare)
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Elemental Substitution of Two-Dimensional Transition Metal Dichalcogenides (MoSe2 and MoTe2) : Implications for Enhanced Gas Sensing
- 2019
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Ingår i: ACS Sensors. - : American Chemical Society (ACS). - 2379-3694. ; 4:10, s. 2646-2653
-
Tidskriftsartikel (refereegranskat)abstract
- The quest for a suitable material with the potential of capturing toxic nitrogen-containing gases (NH3, NO, and NO2) has motivated us to explore the structural, electronic, and gas-sensing properties of transition metal dichalcogenides (TMDs); MoSe2 and MoTe2. Spin-polarized density functional theory (DFT) calculations demonstrate weak binding of nitrogen-containing gases (NCGs) with the pristine TMDs, which limits the use of the latter as efficient sensing materials. However, suitable elemental substitutions improve the binding mechanism enormously. Our dispersion-corrected DFT calculations revealed that Se (Te) substitution with Ge (Sb) in MoSe2 (MoTe2) not only enhances the binding energies but also causes a significant variation in the electronic properties and work functions. A charge-transfer mechanism based on Bader analysis indicates that transfer of charges from MoSe2-Ge (MoTe2-Sb) to the NCGs is responsible for the improvement in the binding characteristics. Based on our findings, it is evident that 2.08% of elemental substitutional makes both MoSe2 and MoTe2 promising materials for NH3, NO, and NO2 gas sensing.
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| 18. |
- Panigrahi, Puspamitra, et al.
(författare)
-
Enhancing energy storage efficiency of lithiated carbon nitride (C7N6) monolayers under co-adsorption of H-2 and CH4
- 2021
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 46:38, s. 19988-19997
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Tidskriftsartikel (refereegranskat)abstract
- There is a great interest in the design of innovative concepts and strategies of nitrogen rich carboneous materials for exploring their hydrogen (H-2) storage properties. Methane (CH4) storage can be an alternative to H-2 because the combustion energy of the former is around three times higher than the latter. However, strong inter-molecular repulsion between the CH4 molecules is a major bottleneck to achieve a high gravimetric density. In this study, we use first principles density functional calculations to investigate the coadoption of H-2 and CH4 on Li decorated carbon nitride (Li-C7N6) monolayer. The repulsion between CH4 molecules has been avoided by keeping them in asymmetric configuration whereas the repulsion between CH4-H-2 is in moderation due to the exploitation of open Li doped sites on C7N6 surface. Though Li-C7N6 has a lower H-2 or CH4 storage capacity due to weak van der Waals interactions, the capacity could be doubled with a novel strategy of co-mixing of H-2 with CH4 which results into a significantly high gravimetric density of 8.1 wt%. This clearly shows that the CH4-H-2 co-mixing strategies have the potential to further propel the prospects of C7N6 monolayers for reversible clean energy storage applications.
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| 19. |
- Panigrahi, Puspamitra, et al.
(författare)
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Exploring the Full Potential of Functional Si2BN Nanoribbons As Highly Reversible Anode Materials for Mg-Ion Battery
- 2021
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 35:15, s. 12688-12699
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Tidskriftsartikel (refereegranskat)abstract
- Efficient energy storage devices like rechargeable batteries have a vital role in the modern society to cater for an ever-increasing demand of energy. In this context, magnesium-ion batteries (MIBs) have emerged as high-capacity energy storage systems. However, the progress in this area is hindered due to the lack of suitable anode materials for efficient Mg2+ ion storage and diffusion. In this study, using state-of-the-art density functional theory (DFT) simulations, we have systematically investigated novel one-dimensional Si2BN nanoribbons as anode materials for MIBs applications. Our calculations confirm the structural stability and metallic character of pristine (Si2BN) and hydrogen functionalized (Si2BN-H) nanoribbons upon Mg adsorptions. We find Mg adsorption energies in the ranges of -1.2 to -1.8 (-1.8 to -2.0) eV for 25% (20%) coverages in Si2BN (Si2BN-H), respectively, which are strong enough to mitigate the Mg aggregation. Maximum specific capacities of 661.865 (550.421) mAh g(-1) and open-circuit voltages of 0.7-1.1 (0.6-0.8) V are found for Si2BN (Si2BN-H), respectively. Diffusion barrier calculations based on nudge elastic band (NEB) methods reveal a relatively low barrier of 0.14 eV, which guarantees a robust diffusion of Mg ions and faster charge/ discharge capability of Si2BN nanoribbons. These intriguing features confirm the potential of functional Si2BN nanoribbons as promising anode materials for MIBs.
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| 20. |
- Panigrahi, Puspamitra, et al.
(författare)
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Hole induced Jahn Teller distortion ensuing ferromagnetism in Mn-MgO : bulk, surface and one dimensional structures
- 2014
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 26:26, s. 265801-
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Tidskriftsartikel (refereegranskat)abstract
- Using density functional theory, we investigate the magnetic properties of Mn doped MgO in its bulk (3D), surface (2D) and one dimensional (1D) structures. At a low dilute limit (1.5 %), the Mn impurity behaves indifferent to its position in 3D but energetically prefers to be on one of the surfaces of 2D and 1D structures. At a higher dilute limit (3.1 %), the Mn impurities stabilizing at Mn-d((3+)) ionic states prefer to be in a close configuration (4.2 angstrom compared to 5.95 angstrom) and the antiferromagnetic ordering (AFM) between them is preferred over the ferromagnetic ordering. The n-type extrinsic defects (O vacancy), when introduced to Mn doped MgO structures, also result in similar AFM exchanges as between the Mn impurities. However, the p-type defects (Mg vacancy) in the Mn doped MgO structures result in a reduced magnetic moment for the Mn atoms and bring a significant Jahn Teller (JT)-type of distortion to the e(g) and t(2)g degenerate states of Mn-d((3+)) ions. The strong hybridization between distorted Mnd states and O-2p states results in a FM exchange coupling between the Mn ions, in all the three mentioned Mn doped MgO structures. As we move from 3D to 2D, to 1D structures, the influence of JT distortion decreases, reflecting a decreasing trend for the strength of the FM
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| 21. |
- Panigrahi, Puspamitra, et al.
(författare)
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Remarkable improvement in hydrogen storage capacities of two-dimensional carbon nitride (g-C3N4) nanosheets under selected transition metal doping
- 2020
-
Ingår i: International journal of hydrogen energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0360-3199 .- 1879-3487. ; 45:4, s. 3035-3045
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Tidskriftsartikel (refereegranskat)abstract
- We have performed DFT simulations to quest for an optimal material for onboard hydrogen (H-2) storage applications. Using first-principles calculations, we established that the selected transition metals (M: Sc, Ti, Ni, V) decorated two-dimensional (2D) g-C3N4 sheets as optimal materials with reversible and significantly high H-2 gravimetric densities. By effectively avoiding metal-metal (M-M) clustering effect in case of mono doping, up to four molecules of H-2 per dopant could be adsorbed with an average binding energy of around 0.30-0.6 eV/H-2, which is ideal for practical applications. Decorating the g-C3N4 sheet with (M-M) dimers, the systems are found to be even more efficient for H-2 binding than single dopant decoration. The stability of these M decorated g-C3N4 sheets have been confirmed with ab-initio molecular dynamics simulations. We have further calculated the H-2 desorption temperatures of metal decorated g-C3N4 sheets, which confirms the practical application of these metal decorated sheets at ambient working conditions.
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| 22. |
- Panigrahi, Puspamitra, et al.
(författare)
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Stacked Si2BN monolayers as ultra-high-capacity anode material for divalent Mg-ion batteries
- 2022
-
Ingår i: FlatChem. - : Elsevier. - 2452-2627. ; 36
-
Tidskriftsartikel (refereegranskat)abstract
- In pursuit of developing next-generation energy storage systems, there has been increasing effort in multivalent rechargeable batteries, such as magnesium-ion batteries (MgIBs). Non-toxicity, earth abundance, and high storage capacity due to their divalent nature make MgIBs an ideal alternative to the existing lithium-ion batteries (LIBs). However, exploring efficient electrode materials capable of storing large quantities of Mg ions is one of the biggest challenges in actualizing MgIBs. Here first-principles density functional theory (DFT) simulations are employed to explore the potential of Si2BN monolayers as a novel anode material for MgIBs. We find that under the maximum coverage effect, the stacked Si2BN could attain a specific capacity of 359.94 mAh g-1, which further enhances to 1418.45 mAh g-1 with a defect concentration of 12 %. The open-circuit voltages fall in the ranges of 0.42-0.46 V and 0.88-0.98 V for the pristine and defected Si2BN, respectively. Diffusion barrier calculations reveal that Mg ions diffuse 125 times faster on pristine Si2BN than the defected one. Our simulations determine that the electronic structures, binding mechanism, equilibrium cell voltages, ionic mobilities, and thermal stabilities of stacked Si2BN make it an excellent anode material for MgIBs.
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| 23. |
- Panigrahi, Puspamitra, et al.
(författare)
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Two-Dimensional Bismuthene Nanosheets for Selective Detection of Toxic Gases
- 2022
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 5:2, s. 2984-2993
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Tidskriftsartikel (refereegranskat)abstract
- An in-depth understanding of the practical sensing mechanism of two-dimensional (2D) materials is critically important for the design of efficient nanosensors toward environmentally toxic gases. Here, we have performed van der Waals-corrected density functional theory (DFT) simulations along with nonequilibrium Green’s function (NEGF) to investigate the structural, electronic, transport, thermodynamic, and gas-sensing properties of pristine and defect-crafted bismuthene (bBi) sheets toward sulfur- (H2S, SO2) and nitrogen-rich (NH3, NO2) toxic gases. It is revealed that the electrical conductivities of pristine and defective bBi sheets are altered upon the adsorption of incident gases, which have been verified through transport calculation coupled with the work function and electronic density of states. Our calculations disclose that bBi sheets show superior and selective gas-sensing performance toward NO2 molecules among the studied gases due to a significant charge redistribution and more potent adsorption energies. We find that the mono- and divacancy-induced bBi sheets have enhanced sensitivity because the adsorption behavior is driven by a considerable change in the electrostatic potential difference between the sheets and the gas molecules. We further performed statistical thermodynamic analysis to quantify the gas adsorption abilities at the practical temperature and pressures for the studied gas samples. This work divulges the higher sensitivity and selectivity of bBi sheets toward hazard toxins such as NO2 under practical sensing conditions of temperature and pressure.
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| 24. |
- Panigrahi, Puspamitra, et al.
(författare)
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Two-dimensional Janus monolayers of MoSSe as promising sensor towards selected adulterants compounds
- 2021
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 542
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Tidskriftsartikel (refereegranskat)abstract
- Selective detection of different types of adulterants present in food items is necessary and efficient nano sensors for such applications are of vital importance. In this study, recently synthesized two-dimensional (2D) Janus monolayer of MoSSe has been explored to detect various food adulterants like formalin (CH2O), histamine (C5H9N3) and hydrogen peroxide (H2O2). By using first principles density functional theory calculations, we find that the incident adulterants weakly bind with pristine MoSSe, however the adsorption energies (E-ads) are significantly improved upon vacancy defects and foreign elements substitutions. Furthermore, the sensing mechanism is studied in presence of water for the applications in practical working conditions. Energetic evaluation shows that both H2O2 and histamine result into stronger E(ads )as compared to formalin over defect induced MoSSe; whereas, the presence of water further enhances the adsorption of H2O2. In addition to the adsorption characteristics, charge transfer mechanism and electronic structures of pristine and defect induced MoSSe monolayers upon the exposure of studied adulterants have also been studied. Boltzmann thermochemical statistics further verified the explicabilities of pristine and defected MoSSe monolayers for in vitro test of adulterants in food products. Suitable E-ads values and measurable changes in the electronic properties indicate the potential of MoSSe monolayers as efficient nano sensors towards selected adulterants for their applications in food processing, biotechnology, healthcare and medical laboratories.
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| 25. |
- Panigrahi, Puspamitra, et al.
(författare)
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Two-Dimensional Nitrogenated Holey Graphene (C2N) Monolayer Based Glucose Sensor for Diabetes Mellitus
- 2022
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 573
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Tidskriftsartikel (refereegranskat)abstract
- Real-time monitoring of sugar molecules is crucial for diagnosis, controlling, and preventing diabetes. Here, we have proposed the potential of porous C2N monolayer-based glucose sensor to detect the sugar molecules (glucose, fructose, and xylose) by employing the van der Waals interactions corrected first-principles density functional theory and non-equilibrium Green’s function methods. The binding energy turns out to be -0.93 (-1.31) eV for glucose, -0.84 (-1.23) eV for fructose, and -0.81 (-1.30) eV for xylose in gas phase (aqueous medium). The Bader charge analysis reveals that the C2N monolayer donates charge to the sugar molecules. The dimensionless electron localization function highlights that glucose, fructose, and xylose bind through physisorption. The adsorption of sugar molecules on the C2N monolayer increases the workfunction compared to 3.54 eV (pristine C2N) with about 2.00 eV, indicating a suppressed probability of electron mobility. The electronic transport properties of C2N based device reveals distinct characteristics and zero-bias transmissions. The distinctive properties of the C2N monolayer can be indexed as promising identifiers for glucose sensors to detect blood sugar.
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| 26. |
- Sagynbaeva, Myskal, et al.
(författare)
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Complementing the adsorption energies of CO2, H2S and NO2 to h-BN sheets by doping with carbon
- 2015
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Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 109:5
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Tidskriftsartikel (refereegranskat)abstract
- We predict the adsorption proficiency of hexagonal boron nitride (h-BN) sheets to toxic gas molecules like CO2, H2S and NO2 on the basis of first-principles density functional theory calculations. The computed energies predict the pristine h-BN sheet to have very little affinity towards the mentioned gas molecules. However, while doping C at the N site of the h-BN sheet brings a significant enhancement to the estimated adsorption energies, doping C at B site of the sheet is found to be energetically not so favorable. To have a higher coverage effect, the concentration of C doping on the h-BN sheet is further increased which resulted in upsurging the adsorption energies for the mentioned gas molecules. Among the three, CO2, H2S are found to be physisorbed to the C-doped h-BN sheets, where as the C-doped sheets are found to have strong affinity towards NO2 gas molecules. Copyright (C) EPLA, 2015
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| 27. |
- Sagynbaeva, Myskal, et al.
(författare)
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Tweaking the magnetism of MoS2 nanoribbon with hydrogen and carbon passivation
- 2014
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 25:16, s. 165703-
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Tidskriftsartikel (refereegranskat)abstract
- Using density functional theory (DFT), we report the modulated electronic and magnetic properties of MoS2 nanoribbon by passivating the ribbon edges with H and C separately. For the modeled symmetric MoS2 nanoribbon with a zig-zag type edge, one side is terminated at Mo and the other side is terminated at S. For the zig-zag type, we have studied two ribbons of width similar to 3 angstrom and 6 angstrom respectively. Both of these pristine zig-zag type nanoribbons are found to be metallic and also ferromagnetic. However, the increase in the ribbon width results in a decrease in the net magnetic moment of the nanoribbon. Thereafter, we study the modulated electronic and magnetic properties of the nanoribbon of similar to 3 angstrom width by saturating the ribbon edges with H and C. In one case, by passivating the zig-zag type ribbon with H at the S terminated edge, we find a net increase in magnetic moment of the ribbon when compared with the pristine one. Furthermore, when the ribbon is passivated with H at both of the edges, the net magnetic moment shows a decreasing trend. In another case, the zig-zag nanoribbon is passivated with C in a similar fashion to H and we find with one edge passivation the net magnetic moment of the ribbon decreases, whereas with both edges C passivated the ribbon magnetism increases significantly. However, the nanoribbon modeled with the armchair type of edge and terminated with Mo at both sides is found to be non-magnetic and semiconducting. Passivating the armchair type nanoribbon with H and C, we find the band gap shows an increasing trend when going from one side to both sides passivation. In all cases, the armchair type nanoribbons show non-magnetic behavior.
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