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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
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.

Keyword
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
Keyword
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
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
Keyword
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
Ouyang, T., Qian, Z., Ahuja, R. & Liu, X. (2018). First-principles investigation of CO adsorption on pristine, C-doped and N-vacancy defected hexagonal AlN nanosheets. Applied Surface Science, 439, 196-201
Open this publication in new window or tab >>First-principles investigation of CO adsorption on pristine, C-doped and N-vacancy defected hexagonal AlN nanosheets
2018 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 439, p. 196-201Article in journal (Refereed) Published
Abstract [en]

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.

Keyword
AlN nanosheet, Doping, Electronic structure, DFT-D2, First-principles, CO sensing
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-351622 (URN)10.1016/j.apsusc.2018.01.040 (DOI)000427457100024 ()
Available from: 2018-06-13 Created: 2018-06-13 Last updated: 2018-06-13Bibliographically approved
Banerjee, A., Araujo, R. B., Sjödin, M. & Ahuja, R. (2018). Identifying the tuning key of disproportionation redox reaction in terephthalate: A Li-based anode for sustainable organic batteries. Nano Energy, 47, 301-308
Open this publication in new window or tab >>Identifying the tuning key of disproportionation redox reaction in terephthalate: A Li-based anode for sustainable organic batteries
2018 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 47, p. 301-308Article in journal (Refereed) Published
Abstract [en]

The ever-increasing consumption of energy storage devices has pushed the scientific community to realize strategies toward organic electrodes with superior properties. This is owed to advantages such as economic viability and eco-friendliness. In this context, the family of conjugated dicarboxylates has emerged as an interesting candidate for the application as negative electrodes in advanced Li-ion batteries due to the revealed thermal stability, rate capability, high capacity and high cyclability. This work aims to rationalize the effects of small molecular modifications on the electrochemical properties of the terephthalate anode by means of first principles calculations. The crystal structure prediction of the investigated host compounds dilithium terephthalate (Li2TP) and diethyl terephthalate (Et2Li0TP) together with their crystal modification upon battery cycling enable us to calculate the potential profile of these materials. Distinct underlying mechanisms of the redox reactions were obtained where Li2TP comes with a disproportionation reaction while Et2Li0TP displays sequential redox reactions. This effect proved to be strongly correlated to the Li coordination number evolution upon the Li insertion into the host structures. Finally, the calculations of sublimation enthalpy inferred that polymerization techniques could easily be employed in Et2Li0TP as compared to Li2TP. Similar results are observed with methyl, propyl, and vinyl capped groups. That could be a strategy to enhance the properties of this compound placing it into the gallery of the new anode materials for state of art Li-batteries.

Keyword
Li-ion organic battery, Lithium terephthalate, Disproportionation, Redox potential
National Category
Physical Chemistry Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-354095 (URN)10.1016/j.nanoen.2018.02.038 (DOI)000430057000031 ()
Funder
Swedish Research Council, 2016-06014
Available from: 2018-06-19 Created: 2018-06-19 Last updated: 2018-06-19Bibliographically approved
Pandey, K., Singh, D., Gupta, S. K., Yadav, P., Sonvane, Y., Lukacevic, I., . . . Ahuja, R. (2018). Improving electron transport in the hybrid perovskite solar cells using CaMnO3-based buffer layer. Nano Energy, 45, 287-297
Open this publication in new window or tab >>Improving electron transport in the hybrid perovskite solar cells using CaMnO3-based buffer layer
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2018 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 45, p. 287-297Article in journal (Refereed) Published
Abstract [en]

In the present article, the detailed analyses of interface properties and device performance of inorganic perovskite CaMnO3-based buffer layer hybrid perovskite solar cell have been undertaken. Analyses are based on ab initio simulations and macroscopic modelling. A thorough study of electronic and optical properties and interface charge dynamics revealed that CaMnO3 presents a better candidate for the electron transport material in thin film hole transporting material free hybrid perovskite solar cells with the planar architecture than the most common anatase TiO2. This result is founded on the more appropriate band gap and better band alignment with the hybrid perovskite, leading to the faster charge carrier mobility, improved charge transfer and reduced exciton recombination. The results from theoretical simulations are justified by the solar cell model, which explored the basic cell characteristics and parameters: open circuit voltage, short circuit current, fill factor and efficiency, as the functions of cell performance factors, like defect density, diffusion length, absorber layer thickness and band offset. Our model suggests an unoptimized device with a photo-conversion efficiency of almost 10% for the low defect concentrations under 10(15). With efficiency in the upper range for HTM free perovskite solar cells, we propose that the CaMnO3-based solar cell poses as an improvement upon the up to now most frequently used ones and provides important step toward their commercialisation.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keyword
Perovskite solar cell, Electron transport layer, Charge transfer, Interface junction, Density functional theory
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-348844 (URN)10.1016/j.nanoen.2018.01.009 (DOI)000425396400032 ()
Funder
Swedish Research Council
Available from: 2018-04-23 Created: 2018-04-23 Last updated: 2018-04-23Bibliographically approved
Shi, S., Zhu, L., Zhang, H., Sun, Z. & Ahuja, R. (2018). Mapping the relationship among composition, stacking fault energy and ductility in Nb alloys: A first-principles study. Acta Materialia, 144, 853-861
Open this publication in new window or tab >>Mapping the relationship among composition, stacking fault energy and ductility in Nb alloys: A first-principles study
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2018 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 144, p. 853-861Article in journal (Refereed) Published
Abstract [en]

Transition metals (TMs) are extensively used to improve the mechanical properties of niobium based alloy, one of the most promising high-temperature materials. Yet the microscopic mechanism of the alloying effects of these transition metals on the mechanical properties is unclear. In this study, we have mapped out the composition-SFE-ductility relationship for TM-alloyed Nb systems by comprehensively investigating the unstable stacking fault energies (SFEs), gamma(us), and the ductility in binary and ternary Nb alloys using the first-principles calculations. It is found that the valence electron concentration can be used as the key descriptor to evaluate the SFE of Nb matrix, which is applicable to both binary and ternary alloys. The microscopic mechanism arises from the electron redistribution in the local stacking fault area. Moreover, for ternary Nb-Ti based alloys, the interaction between Ti and the third alloying elements has negligible effect on the SFE of the systems, and the valence-electron rule still dominates. The alloying effects on the ductility are further illustrated based on the ratio between surface energies and SFEs. The composition-SFE-ductility map obtained by our theoretical calculations is calibrated by available experimental data.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2018
Keyword
Stacking-fault energy, Mechanical alloying, Ductility, First-principles calculations
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-347092 (URN)10.1016/j.actamat.2017.11.029 (DOI)000424067100078 ()
Available from: 2018-03-26 Created: 2018-03-26 Last updated: 2018-03-26Bibliographically approved
Yang, X., Li, H., Hu, M., Liu, Z., Wärnå, J., Cao, Y., . . . Luo, W. (2018). Mechanical properties investigation on single-wall ZrO2 nanotubes: A finite element method with equivalent Poisson's ratio for chemical bonds. Physica. E, Low-Dimensional systems and nanostructures, 98, 23-28
Open this publication in new window or tab >>Mechanical properties investigation on single-wall ZrO2 nanotubes: A finite element method with equivalent Poisson's ratio for chemical bonds
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2018 (English)In: Physica. E, Low-Dimensional systems and nanostructures, ISSN 1386-9477, E-ISSN 1873-1759, Vol. 98, p. 23-28Article in journal (Refereed) Published
Abstract [en]

A method to obtain the equivalent Poisson's ratio in chemical bonds as classical beams with finite element method was proposed from experimental data. The UFF (Universal Force Field) method was employed to calculate the elastic force constants of Zr-O bonds. By applying the equivalent Poisson's ratio, the mechanical properties of single-wall ZrNTs (ZrO2 nanotubes) were investigated by finite element analysis. The nanotubes' Young's modulus (Y), Poisson's ratio (nu) of ZrNTs as function of diameters, length and chirality have been discussed, respectively. We found that the Young's modulus of single-wall ZrNTs is calculated to be between 350 and 420 GPa.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keyword
Signal-wall ZrO2 nanotubes, Mechanical properties, Finite element method, Poisson's ratio
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-347532 (URN)10.1016/j.physe.2017.10.005 (DOI)000425118100005 ()
Funder
Swedish Research Council
Available from: 2018-04-04 Created: 2018-04-04 Last updated: 2018-04-04Bibliographically approved
Tsuppayakorn-aek, P., Luo, W., Ahuja, R. & Bovornratanaraks, T. (2018). The High-Pressure Superconducting Phase of Arsenic. Scientific Reports, 8, Article ID 3026.
Open this publication in new window or tab >>The High-Pressure Superconducting Phase of Arsenic
2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 3026Article in journal (Refereed) Published
Abstract [en]

Ab initio random structure searching (AIRSS) technique is predicted a stable structure of arsenic (As). We find that the body-centered tetragonal (bct) structure with spacegroup I4(1)/acd to be the stable structure at high pressure. Our calculation suggests transition sequence from the simple cubic (sc) structure transforms into the host-guest (HG) structure at 41 GPa and then into the bct structure at 81 GPa. The bct structure has been calculated using ab initio lattice dynamics with finite displacement method confirm the stability at high pressure. The spectral function alpha F-2 of the bct structure is higher than those of the body-centered cubic (bcc) structure. It is worth noting that both bct and bcc structures share the remarkable similarity of structural and property. Here we have reported the prediction of temperature superconductivity of the bct structure, with a T-c of 4.2 K at 150 GPa.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2018
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-348108 (URN)10.1038/s41598-018-20088-8 (DOI)000424985800064 ()29445106 (PubMedID)
Available from: 2018-04-11 Created: 2018-04-11 Last updated: 2018-04-11Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-1231-9994

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