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Cheng, K., Guo, Y., Han, N., Jiang, X., Zhang, J., Ahuja, R., . . . Zhao, J. (2018). 2D lateral heterostructures of group-III monochalcogenide: Potential photovoltaic applications. Applied Physics Letters, 112(14), Article ID 143902.
Open this publication in new window or tab >>2D lateral heterostructures of group-III monochalcogenide: Potential photovoltaic applications
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2018 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, no 14, article id 143902Article in journal (Refereed) Published
Abstract [en]

Solar photovoltaics provides a practical and sustainable solution to the increasing global energy demand. Using first-principles calculations, we investigate the energetics and electronic properties of two-dimensional lateral heterostructures by group-III monochalcogenides and explore their potential applications in photovoltaics. The band structures and formation energies from supercell calculations demonstrate that these heterostructures retain semiconducting behavior and might be synthesized in laboratory using the chemical vapor deposition technique. According to the computed band offsets, most of the heterojunctions belong to type II band alignment, which can prevent the recombination of electron-hole pairs. Besides, the electronic properties of these lateral heterostructures can be effectively tailored by the number of layers, leading to a high theoretical power conversion efficiency over 20%.

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2018
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-352696 (URN)10.1063/1.5020618 (DOI)000429344100038 ()
Available from: 2018-06-08 Created: 2018-06-08 Last updated: 2018-06-08Bibliographically approved
Minakshi, M., Watcharatharapong, T., Chakraborty, S. & Ahuja, R. (2018). A combined theoretical and experimental approach of a new ternary metal oxide in molybdate composite for hybrid energy storage capacitors. APL MATERIALS, 6(4), Article ID 047701.
Open this publication in new window or tab >>A combined theoretical and experimental approach of a new ternary metal oxide in molybdate composite for hybrid energy storage capacitors
2018 (English)In: APL MATERIALS, ISSN 2166-532X, Vol. 6, no 4, article id 047701Article in journal (Refereed) Published
Abstract [en]

Sustainable energy sources require an efficient energy storage system possessing excellent electrochemical properties. The better understanding of possible crystal configurations and the development of a new ternary metal oxide in molybdate composite as an electrode for hybrid capacitors can lead to an efficient energy storage system. Here, we reported a new ternary metal oxide in molybdate composite [(Mn1/3Co1/3Ni1/3)MoO4] prepared by simple combustion synthesis with an extended voltage window (1.8 V vs. Carbon) resulting in excellent specific capacity 35 C g−1 (58 F g−1) and energy density (50 Wh kg−1 at 500 W kg−1) for a two electrode system in an aqueous NaOH electrolyte. The binding energies measured for Mn, Co, and Ni 2p are consistent with the literature, and with the metal ions being present as M(II), implying that the oxidation states of the transition metals are unchanged. The experimental findings are correlated well through density functional theory based electronic structure calculations. Our reported work on the ternary metal oxide studies (Mn1/3Co1/3Ni1/3)MoO4 suggests that will be an added value to the materials for energy storage.

National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-355692 (URN)10.1063/1.4994750 (DOI)000431141500010 ()
Available from: 2018-07-04 Created: 2018-07-04 Last updated: 2018-07-04Bibliographically approved
Hussain, T., Vovusha, H., Kaewmaraya, T., Amornkitbamrung, V. & Ahuja, R. (2018). Adsorption characteristics of DNA nucleobases, aromatic amino acids and heterocyclic molecules on silicene and germanene monolayers. Sensors and actuators. B, Chemical, 255, 2713-2720
Open this publication in new window or tab >>Adsorption characteristics of DNA nucleobases, aromatic amino acids and heterocyclic molecules on silicene and germanene monolayers
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2018 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 255, p. 2713-2720Article in journal (Refereed) Published
Abstract [en]

Binding of DNA/RNA nucleobases, aromatic amino acids and heterocyclic molecules on two-dimensional silicene and germanene sheets have been investigated for the application of sensing of biomolecules using first principle density functional theory calculations. Binding energy range for nucleobases, amino acids and heterocyclic molecules with both the sheets have been found to be (0.43-1.16 eV), (0.70-1.58 eV) and (0.22-0.96 eV) respectively, which along with the binding distances show that these molecules bind to both sheets by physisorption and chemisorption process. The exchange of electric charges between the monolayers and the incident molecules has been examined by means of Bader charge analysis. It has been observed that the introduction of DNA/RNA nucleobases, aromatic amino acids and heterocyclic molecules alters the electronic properties of both silicene and germanene nano sheets as studied by plotting the total (TDOS) and partial (PDOS) density of states. The DOS plots reveal the variation in the band gaps of both silicene and germanene caused by the introduction of studied molecules. Based on the obtained results we suggest that both silicene and germanene monolayers in their pristine form could be useful for sensing of biomolecules.

Keywords
Adsorption characteristics, DNA nucleobases, Aromatic amino acids, Heterocyclic molecules
National Category
Materials Engineering
Identifiers
urn:nbn:se:uu:diva-341967 (URN)10.1016/j.snb.2017.09.083 (DOI)000414686500032 ()
Funder
Swedish Research CouncilCarl Tryggers foundation StandUp
Available from: 2018-02-19 Created: 2018-02-19 Last updated: 2018-02-19Bibliographically approved
Das, S., Swain, D., Araujo, R. B., Shi, S., Ahuja, R., Row, T. N. G. & Bhattacharyya, A. J. (2018). Alloying in an Intercalation Host: Metal Titanium Niobates as Anodes for Rechargeable Alkali-Ion Batteries. Chemistry - An Asian Journal, 13(3), 299-310
Open this publication in new window or tab >>Alloying in an Intercalation Host: Metal Titanium Niobates as Anodes for Rechargeable Alkali-Ion Batteries
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2018 (English)In: Chemistry - An Asian Journal, ISSN 1861-4728, E-ISSN 1861-471X, Vol. 13, no 3, p. 299-310Article in journal (Refereed) Published
Abstract [en]

We discuss here a unique flexible non-carbonaceous layered host, namely, metal titanium niobates (M-Ti-niobate, M: Al3+, Pb2+, Sb3+, Ba2+, Mg2+), which can synergistically store both lithium ions and sodium ions via a simultaneous intercalation and alloying mechanisms. M-Ti-niobate is formed by ion exchange of the K+ ions, which are specifically located inside galleries between the layers formed by edge and corner sharing TiO6 and NbO6 octahedral units in the sol-gel synthesized potassium titanium niobate (KTiNbO5). Drastic volume changes (approximately 300-400%) typically associated with an alloying mechanism of storage are completely tackled chemically by the unique chemical composition and structure of the M-Ti-niobates. The free space between the adjustable Ti/Nb octahedral layers easily accommodates the volume changes. Due to the presence of an optimum amount of multivalent alloying metal ions (50-75% of total K+) in the M-Ti-niobate, an efficient alloying reaction takes place directly with ions and completely eliminates any form of mechanical degradation of the electroactive particles. The M-Ti-niobate can be cycled over a wide voltage range (as low as 0.01V) and displays remarkably stable Li+ and Na+ ion cyclability (>2 Li+/Na+ per formula unit) for widely varying current densities over few hundreds to thousands of successive cycles. The simultaneous intercalation and alloying storage mechanisms is also studied within the density functional theory (DFT) framework. DFT expectedly shows a very small variation in the volume of Al-titanium niobate following lithium alloying. Moreover, the theoretical investigations also conclusively support the occurrence of the alloying process of Li ions with the Al ions along with the intercalation process during discharge. The M-Ti-niobates studied here demonstrate a paradigm shift in chemical design of electrodes and will pave the way for the development of a multitude of improved electrodes for different battery chemistries.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2018
Keywords
alloying, anode, intercalation, rechargeable battery, synergy
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-345713 (URN)10.1002/asia.201701602 (DOI)000424106500016 ()29280560 (PubMedID)
Funder
Swedish Research CouncilStandUp
Available from: 2018-03-14 Created: 2018-03-14 Last updated: 2018-03-14Bibliographically approved
Smazna, D., Rodrigues, J., Shree, S., Postica, V., Neubueser, G., Martins, A. F., . . . Mishra, Y. K. (2018). Buckminsterfullerene hybridized zinc oxide tetrapods: defects and charge transfer induced optical and electrical response. Nanoscale, 10(21), 10050-10062
Open this publication in new window or tab >>Buckminsterfullerene hybridized zinc oxide tetrapods: defects and charge transfer induced optical and electrical response
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2018 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 21, p. 10050-10062Article in journal (Refereed) Published
Abstract [en]

Buckminster fullerene (C-60) based hybrid metal oxide materials are receiving considerable attention because of their excellent fundamental and applied aspects, like semiconducting, electron transfer, luminescent behaviors, etc. and this work briefly discusses the successful fabrication of C-60 decorated ZnO tetrapod materials and their detailed structure-property relationships including device sensing applications. The electron microscopy investigations indicate that a quite dense surface coverage of ZnO tetrapods with C-60 clusters is achieved. The spectroscopy studies confirmed the identification of the C-60 vibrational modes and the C-60 induced changes in the absorption and luminescence properties of the ZnO tetrapods. An increased C-60 concentration on ZnO results in steeper ZnO bandgap absorption followed by well-defined free exciton and 3.31 eV line emissions. As expected, higher amounts of C-60 increase the intensity of C-60-related visible absorption bands. Pumping the samples with photons with an energy corresponding to these absorption band maxima leads to additional emission from ZnO showing an effective charge transfer phenomenon from C-60 to the ZnO host. The density of states model obtained from DFT studies for pure and C-60 coated ZnO surfaces confirms the experimental observations. The fabricated C-60-ZnO hybrid tetrapod based micro- and nanodevices showed interesting ethanol gas sensing characteristics.

National Category
Condensed Matter Physics Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-357683 (URN)10.1039/c8nr01504j (DOI)000434313200027 ()29781017 (PubMedID)
Funder
EU, Horizon 2020Swedish Research Council, 2016-06014
Available from: 2018-08-20 Created: 2018-08-20 Last updated: 2018-08-20Bibliographically approved
Li, J., He, X., Peng, C. & Ahuja, R. (2018). Chemical Bonding of Unique CO on Fe(100). The Journal of Physical Chemistry C, 122(16), 9062-9074
Open this publication in new window or tab >>Chemical Bonding of Unique CO on Fe(100)
2018 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 16, p. 9062-9074Article in journal (Refereed) Published
Abstract [en]

At low coverage, CO molecules are known to preferentially occupy the hollow sites of Fe(100) with considerably inclined molecular orientations. This CO configuration serves as the precursor state of CO dissociation, which is particularly important in several important catalytic reactions. In this study, we present a unique bonding picture of the precursor state from the spin, charge, and orbital perspectives. From the spin and orbital views, we show the antiferromagenetic nature of the adsorbate–metal coupling, where 2π magnetism prevails with a dominant spin-down channel. However, contrasting tendencies are found for the two 1π orbitals in two orthogonal directions: the 1π orbital in the vertical plane loses its symmetry, whereas the other 1π orbital remains intact with a preserved symmetry. The 1π symmetry in the vertical plane favors the 1π → 2π* excitation mechanism owing to the partial opening up of the 1π symmetry. In the charge perspective, we have identified a charge transfer mechanism involving the local structural IFeC–C–O motif, in which the surface slightly charges the adsorbate with additional partial electrons located at the surface Fe atoms bonded to the carbon end, whereas the charges of the metallic atoms beneath the IFeC–C–O motif are found to be depleted. In both the adsorbate and metal sides, the depletion of s electrons serves as a good measure of orbital repulsion and delocalization. Interestingly, the carbon and oxygen ends exhibit contrasting electron affinity with the metal surface: the carbon end is attractive, whereas the oxygen end is repulsive in terms of the contrasting charge rearrangement in the bonded metallic atoms.

National Category
Theoretical Chemistry Physical Chemistry Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-356094 (URN)10.1021/acs.jpcc.8b01825 (DOI)000431151200041 ()
Available from: 2018-07-19 Created: 2018-07-19 Last updated: 2018-07-19Bibliographically approved
Hussain, T., Kaewmaraya, T., Chakraborty, S., Vovusha, H., Amornkitbamrung, V. & Ahuja, R. (2018). Defected and Functionalized Germanene-based Nanosensors under Sulfur Comprising Gas Exposure. ACS SENSORS, 3(4), 867-874
Open this publication in new window or tab >>Defected and Functionalized Germanene-based Nanosensors under Sulfur Comprising Gas Exposure
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2018 (English)In: ACS SENSORS, ISSN 2379-3694, Vol. 3, no 4, p. 867-874Article in journal (Refereed) Published
Abstract [en]

Efficient sensing of sulfur containing toxic gases like H2S and SO2 is of the utmost importance due to the adverse effects of these noxious gases. Absence of an efficient 2D-based nanosensor capable of anchoring H2S and SO2 with feasible binding and an apparent variation in electronic properties upon the exposure of gas molecules has motivated us to explore the promise of a germanene nanosheet (Ge-NS) for this purpose. In the present study, we have performed a comprehensive computational investigation by means of DFT-based first-principles calculations to envisage the structural, electronic, and gas sensing properties of pristine, defected, and metal substituted Ge-NSs. Our initial screening has revealed that although interaction of SO2 with pristine Ge-NSs is within the desirable range, H2S binding however falls below the required values to guarantee an effective sensing. To improve the binding characteristics, we have considered the interactions between H2S and SO2 with defected and metal substituted Ge-NS. The systematic removals of Ge atoms from a reasonably large super cell lead to monovacancy, divacancies, and trivacancies in Ge-NS. Similarly, different transition metals like As, Co, Cu, Fe, Ga, Ge, Ni, and Zn have been substituted into the monolayer to realize substituted Ge-NS. Our van der Waals corrected DFT calculations have concluded that the vacancy and substitution defects not only improve the binding characteristics but also enhance the sensing propensity of both H2S and SO2. The total and projected density of states show significant variations in electronic properties of pristine and defected Ge-NSs before and after the exposure to the gases, which are essential in constituting a signal to be detected by the external circuit of the sensor. We strongly believe that our present work would not only advance the knowledge towards the application of Ge-NS-based sensing but also provide motivation for the synthesis of such efficient nanosensor for H2S and SO2 based on Ge monolayer.

Keywords
binding characteristics, nano sheets, substitution, nanostructures, nanosensors
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-355689 (URN)10.1021/acssensors.8b00167 (DOI)000431165200018 ()29582648 (PubMedID)
Funder
Swedish Research CouncilStandUpCarl Tryggers foundation
Available from: 2018-07-05 Created: 2018-07-05 Last updated: 2018-07-05Bibliographically approved
Srivastava, A., Khan, M. S. S. & Ahuja, R. (2018). Electron transport in NH3/NO2 sensed buckled antimonene. Solid State Communications, 272, 1-7
Open this publication in new window or tab >>Electron transport in NH3/NO2 sensed buckled antimonene
2018 (English)In: Solid State Communications, ISSN 0038-1098, E-ISSN 1879-2766, Vol. 272, p. 1-7Article in journal (Refereed) Published
Abstract [en]

The structural and electronic properties of buckled antimonene have been analysed using density functional theory based ab-initio approach. Geometrical parameters in terms of bond length and bond angle are found close to the single ruffle mono-layer of rhombohedral antimony. Inter-frontier orbital analyses suggest localization of lone pair electrons at each atomic centre. Phonon dispersion along with high symmetry point of Brillouin zone does not signify any soft mode. With an electronic band gap of 1.8eV, the quasi-2D nano-surface has been further explored for NH3/NO2 molecules sensing and qualities of interaction between NH3/NO2 gas and antimonene scrutinized in terms of electronic charges transfer. A current-voltage characteristic has also been analysed, using Non Equilibrium Green's function (NEGF), for antimonene, in presence of incoming NH3/NO2 molecules.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2018
Keywords
Antimonene, Sensor, DFT, Adsorption energy, Bandstructure, Transmission spectra
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-350486 (URN)10.1016/j.ssc.2018.01.006 (DOI)000425845300001 ()
Available from: 2018-05-17 Created: 2018-05-17 Last updated: 2018-05-17Bibliographically approved
Panigrahi, P., Naqvi, S. R., Hankel, M., Ahuja, R. & Hussain, T. (2018). Enriching the hydrogen storage capacity of carbon nanotube doped with polylithiated molecules. Applied Surface Science, 444, 467-473
Open this publication in new window or tab >>Enriching the hydrogen storage capacity of carbon nanotube doped with polylithiated molecules
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2018 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 444, p. 467-473Article in journal (Refereed) Published
Abstract [en]

In a quest to find optimum materials for efficient storage of clean energy, we have performed first principles calculations to study the structural and energy storage properties of one-dimensional carbon nanotubes (CNTs) functionalized with polylithiated molecules (PLMs). Van der Waals corrected calculations disclosed that various PLMs like CLi, CLi2, CLi3, OLi, OLi2, OLi3, bind strongly to CNTs even at high doping concentrations ensuring a uniform distribution of dopants without forming clusters. Bader charge analysis reveals that each Li in all the PLMs attains a partial positive charge and transform into Li+ cations. This situation allows multiple H-2 molecules adsorbed with each Li+ through the polarization of incident H-2 molecules via electrostatic and van der Waals type of interaction. With a maximum doping concentration, that is 3CLi(2)/3CLi(3) and 3OLi(2)/3OLi(3) a maximum of 36 H-2 molecules could be adsorbed that corresponds to a reasonably high H-2 storage capacity with the adsorption energies in the range of -0.33 to -0.15 eV/H-2. This suits the ambient condition applications. (C) 2018 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Carbon nanotubes, Polylithiated molecules, Hydrogen storage, Energetics analysis, Charge transfer, Adsorption energies
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-352558 (URN)10.1016/j.apsusc.2018.02.040 (DOI)000429343200056 ()
Funder
Swedish Research Council
Available from: 2018-08-08 Created: 2018-08-08 Last updated: 2018-08-08Bibliographically approved
Jiang, G., Qian, Z., Bououdina, M., Ahuja, R. & Liu, X. (2018). Exploring pristine and Li-doped Mg2NiH4 compounds with potential lithium-storage properties: Ab initio insight. Journal of Alloys and Compounds, 746, 140-146
Open this publication in new window or tab >>Exploring pristine and Li-doped Mg2NiH4 compounds with potential lithium-storage properties: Ab initio insight
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2018 (English)In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 746, p. 140-146Article in journal (Refereed) Published
Abstract [en]

In this work, pure and Li-doped Mg2NiH4 hydrides are explored for potential Li-ion battery conversion anode materials applications from state-of-the-art Density functional theory. The most thermodynamically stable Li-doped Mg2NiH4 structure is determined, which possesses a smaller band gap than pure material and owns a theoretical specific capacity of 975.35 mA h g(-1) and an average voltage of 0.437 V (vs. Li+/Li-0). The Li-doping also improves the diffusion behavior of Li-ion in electrode material especially at 300 K, which implies the promising rate capability of the device at room temperature when the anode material is doped utilizing Li element. The non-empirical values of diffusion coefficients of Li-ion in both pure and Li-doped Mg2NiH4 system are also quantitatively determined from ab initio molecular dynamics. After Li-doping, the diffusion coefficient of Li-ion in the electrode is evidently increased to 1.791 x 10(-9) m(2) s(-1) from the pristine 1.431 x 10(-9) m(2) s(-1) at 300 K and the Li-ion conductivity is also increased. This theoretical study is proposed to encourage the design and experimental modification of better light-metal based hydrides for Li-ion battery conversion anodes applications.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2018
Keywords
Density functional theory, Electronic structures, Conversion anode, Doping, Lithium-storage, Light metal hydrides
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-352562 (URN)10.1016/j.jallcom.2018.02.290 (DOI)000429170300018 ()
Available from: 2018-08-08 Created: 2018-08-08 Last updated: 2018-08-08Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-1231-9994

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