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Author Jalili, Seifollah ♦ Moharramzadeh Goliaei, Elham ♦ Schofield, Jeremy
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY ♦ NANOSCIENCE AND NANOTECHNOLOGY ♦ CATHODES ♦ COMPUTER CALCULATIONS ♦ DENSITY FUNCTIONAL METHOD ♦ ELECTRIC CONDUCTIVITY ♦ ELECTROCATALYSTS ♦ ELECTRONIC STRUCTURE ♦ FUEL CELLS ♦ GROUND STATES ♦ MANGANESE IONS ♦ NANOSTRUCTURES ♦ OXIDES ♦ PERFORMANCE ♦ POTASSIUM COMPOUNDS ♦ SEMICONDUCTOR MATERIALS ♦ TEMPERATURE RANGE 0273-0400 K ♦ THERMAL CONDUCTIVITY ♦ THERMOELECTRIC PROPERTIES ♦ WASTE HEAT
Abstract Density functional theory (DFT) calculations are carried out to investigate the electronic, magnetic and thermoelectric properties of bulk and nanosheet K{sub 1.33}Mn{sub 8}O{sub 16} materials. The catalytic activity and cathodic performance of bulk and nanosheet structures are examined using the Tran-Blaha modified Becke-Johnson (TB-mBJ) exchange potential. Electronic structure calculations reveal an anti-ferromagnetic ground state, with a TB-mMBJ band gap in bulk K{sub 1.33}Mn{sub 8}O{sub 16} that is in agreement with experimental results. Density of state plots indicate a partial reduction of Mn{sup 4+} ions to Mn{sup 3+}, without any obvious sign of Jahn-Teller distortion. Moreover, use of the O p-band center as a descriptor of catalytic activity suggests that the nanosheet has enhanced catalytic activity compared to the bulk structure. Thermoelectric parameters such as the Seebeck coefficient, electrical conductivity, and thermal conductivity are also calculated, and it is found that the Seebeck coefficients decrease with increasing temperature. High Seebeck coefficients for both spin-up and spin-down states are found in the nanosheet relative to their value in the bulk K{sub 1.33}Mn{sub 8}O{sub 16} structure, whereas the electrical and thermal conductivity are reduced relative to the bulk. In addition, figures of merit values are calculated as a function of the chemical potential and it is found that the nanosheet has a figure of merit of ~1 at room temperature, compared to 0.5 for the bulk material. All results suggest that K{sub 1.33}Mn{sub 8}O{sub 16} nanosheets can be used both as a material in waste heat recovery and as an electrocatalyst in fuel cells and batteries. - Graphical abstract: K{sub 1.33}Mn{sub 8}O{sub 16}: bulk and nanosheet. - Highlights: • Electronic properties of bulk and nanosheet forms of K{sub 1.33}Mn{sub 8}O{sub 16} have been studied. • The K{sub 1.33}Mn{sub 8}O{sub 16} nanosheet is a semiconductor while the bulk is a metal. • K{sub 1.33}Mn{sub 8}O{sub 16} Nanosheet is a more efficient electrocatalyst than bulk K{sub 1.33}Mn{sub 8}O{sub 16}. • High figure of merit of K{sub 1.33}Mn{sub 8}O{sub 16} nanosheet makes it an efficient cathode.
ISSN 00224596
Educational Use Research
Learning Resource Type Article
Publisher Date 2017-02-15
Publisher Place United States
Journal Journal of Solid State Chemistry
Volume Number 246


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