scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Highly improved supercapacitance properties of MnFe2O4 nanoparticles by MoS2 nanosheets.

16 Apr 2021-Scientific Reports (Springer Science and Business Media LLC)-Vol. 11, Iss: 1, pp 8378-8378
TL;DR: In this article, MnFe2O4/MoS2 nanoparticles were synthesized via a hydrothermal method and combined with exfoliated MoS2 nanosheets, and the nanocomposite was studied as a supercapacitor.
Abstract: Manganese ferrite (MnFe2O4) nanoparticles were synthesized via a hydrothermal method and combined with exfoliated MoS2 nanosheets, and the nanocomposite was studied as a supercapacitor. X-ray diffractometry and Raman spectroscopy confirmed the crystalline structures and structural characteristics of the nanocomposite. Transmission electron microscopy images showed the uniform size distribution of MnFe2O4 nanoparticles (~ 13 nm) on few-layer MoS2 nanosheets. UV-visible absorption photospectrometry indicated a decrease in the bandgap of MnFe2O4 by MoS2, resulting in a higher conductivity that is suitable for capacitance. Electrochemical tests showed that the incorporation of MoS2 nanosheets largely increased the specific capacitance of MnFe2O4 from 600 to 2093 F/g (with the corresponding energy density and power density of 46.51 Wh/kg and 213.64 W/kg, respectively) at 1 A/g, and led to better charge-discharge cycling stability. We also demonstrated a real-world application of the MnFe2O4/MoS2 nanocomposite in a two-cell asymmetric supercapacitor setup. A density functional theory study was also performed on the MnFe2O4/MoS2 interface to analyze how a MoS2 monolayer can enhance the electronic properties of MnFe2O4 towards a higher specific capacitance.

Content maybe subject to copyright    Report

Citations
More filters
Journal ArticleDOI
TL;DR: In this paper , freestanding carbon nanofibers embedded with bimetallic manganese-iron oxide are fabricated for flexible supercapacitor applications via electrospinning.

20 citations

Journal ArticleDOI
TL;DR: In this article, the authors performed density functional theory calculations to investigate how a vdW heterostructure of heptazine-based graphitic carbon nitride (hg-C3N4) and graphitic zinc oxide (g-ZnO) monolayers is formed.
Abstract: Van der Waals (vdW) heterostructures of two-dimensional monolayers are a relatively new class of materials with highly tunable band alignment, bandgap energy, and bandgap transition type. In this study, we performed density functional theory calculations to investigate how a vdW heterostructure of heptazine-based graphitic carbon nitride (hg-C3N4) and graphitic zinc oxide (g-ZnO) monolayers is formed (hg-C3N4/g-ZnO). This heterostructure is a potential solar-driven photocatalyst for the water-splitting reaction. Upon the formation of the heterostructure, a type-I indirect bandgap (Eg = 2.08 eV) is created with appropriate conduction band minimum and valence band maximum levels relative to the oxidation/reduction potentials for the water-splitting reaction. In addition, a very large electrostatic potential difference of 11.18 eV is generated across the heterostructure, leading to a large, naturally-formed, built-in electric field directing from hg-C3N4 to g-ZnO. The produced electric field forces photogenerated electrons in g-ZnO to transfer toward hg-C3N4, leading to a decrease in the electron–hole recombination rate. We also found that both g-ZnO and hg-C3N4 synergistically lead to higher light absorption of the heterostructure (λmax = 387 nm). Furthermore, band alignment, bandgap energy, and transition type of the heterostructure can be tuned by applying external perpendicular electric fields and biaxial strains. It was found that a strain of +2% leads to a Z-scheme band alignment (Eg = 2.34 eV, direct) and an electric field of 1 V A−1 leads to a type-II heterostructure (Eg = 2.29 eV, indirect), which are both beneficial for efficient water-splitting photocatalysis.

15 citations

Journal ArticleDOI
TL;DR: In this article , the progress made in the design and synthesis of some important metal ferrite nanostructures, their performance as catalysts in organic synthesis and as active electrode materials in supercapacitors (SCs).

15 citations

Journal ArticleDOI
TL;DR: In this paper , a new strategy for the fabrication of emerging MgCo2O4 @Ni3S2 heterostructure array for asymmetric supercapacitors through hydrothermal and subsequent calcination technique is reported.

13 citations

References
More filters
Journal ArticleDOI
TL;DR: QUANTUM ESPRESSO as discussed by the authors is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave).
Abstract: QUANTUM ESPRESSO is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density-functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave). The acronym ESPRESSO stands for opEn Source Package for Research in Electronic Structure, Simulation, and Optimization. It is freely available to researchers around the world under the terms of the GNU General Public License. QUANTUM ESPRESSO builds upon newly-restructured electronic-structure codes that have been developed and tested by some of the original authors of novel electronic-structure algorithms and applied in the last twenty years by some of the leading materials modeling groups worldwide. Innovation and efficiency are still its main focus, with special attention paid to massively parallel architectures, and a great effort being devoted to user friendliness. QUANTUM ESPRESSO is evolving towards a distribution of independent and interoperable codes in the spirit of an open-source project, where researchers active in the field of electronic-structure calculations are encouraged to participate in the project by contributing their own codes or by implementing their own ideas into existing codes.

19,985 citations

Journal ArticleDOI
TL;DR: Novel features are that the pseudopotential itself becomes charge-state dependent, the usual norm-conservation constraint does not apply, and a generalized eigenproblem is introduced.
Abstract: A new approach to the construction of first-principles pseudopotentials is described. The method allows transferability to be improved systematically while holding the cutoff radius fixed, even for large cutoff radii. Novel features are that the pseudopotential itself becomes charge-state dependent, the usual norm-conservation constraint does not apply, and a generalized eigenproblem is introduced. The potentials have a separable form well suited for plane-wave solid-state calculations, and show promise for application to first-row and transition-metal systems.

18,782 citations

Journal ArticleDOI
TL;DR: VESTA has been upgraded to the latest version, VESTA 3, implementing new features including drawing the external mor­phology of crystals, and an extended bond-search algorithm to enable more sophisticated searches in complex molecules and cage-like structures.
Abstract: VESTA is a three-dimensional visualization system for crystallographic studies and electronic state calculations. It has been upgraded to the latest version, VESTA 3, implementing new features including drawing the external mor­phology of crystals; superimposing multiple structural models, volumetric data and crystal faces; calculation of electron and nuclear densities from structure parameters; calculation of Patterson functions from structure parameters or volumetric data; integration of electron and nuclear densities by Voronoi tessellation; visualization of isosurfaces with multiple levels; determination of the best plane for selected atoms; an extended bond-search algorithm to enable more sophisticated searches in complex molecules and cage-like structures; undo and redo in graphical user interface operations; and significant performance improvements in rendering isosurfaces and calculating slices.

15,053 citations

Journal ArticleDOI
TL;DR: Quantum ESPRESSO as discussed by the authors is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave).
Abstract: Quantum ESPRESSO is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density-functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave). Quantum ESPRESSO stands for "opEn Source Package for Research in Electronic Structure, Simulation, and Optimization". It is freely available to researchers around the world under the terms of the GNU General Public License. Quantum ESPRESSO builds upon newly-restructured electronic-structure codes that have been developed and tested by some of the original authors of novel electronic-structure algorithms and applied in the last twenty years by some of the leading materials modeling groups worldwide. Innovation and efficiency are still its main focus, with special attention paid to massively-parallel architectures, and a great effort being devoted to user friendliness. Quantum ESPRESSO is evolving towards a distribution of independent and inter-operable codes in the spirit of an open-source project, where researchers active in the field of electronic-structure calculations are encouraged to participate in the project by contributing their own codes or by implementing their own ideas into existing codes.

13,052 citations

Journal ArticleDOI
TL;DR: For the molecules Be2, F2, and P2 of Table I, the unrestricted Hartree-Fock solution breaks the singlet spin symmetry, even though the density functional solutions do not.
Abstract: For the molecules Be2, F2, and P2 of Table I, the unrestricted Hartree-Fock solution breaks the singlet spin symmetry, even though the density-functional solutions do not. For these broken-symmetry solutions, the UHF atomization energies become 17, 220, and 141 kcalymol, respectively, and the mean absolute error of all the UHF atomization energies becomes 69.8 kcalymol. The PBE correlation energy of the two-electron ions of nuclear charge Z ! ` should be corrected to 20.0479 hartree, consistent with the PBE value v ­ 0.046644 stated in the Letter. The quoted value 20.0482 hartree was obtained from the more refined v ­ 0.046920 of G. G. Hoffman, Phys. Rev. B 45, 8730 (1992). Reference [6] should have been “A. C. Scheiner, J. Baker, and J. W. Andzelm, J. Comput. Chem. (to be published)”.

11,883 citations