K{sub 1.33}Mn{sub 8}O{sub 16} as an electrocatalyst and a cathode

Journal Article · Wed Feb 15 00:00:00 EST 2017 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2016.12.009· OSTI ID:22658210

Jalili, Seifollah ^[1]; Moharramzadeh Goliaei, Elham ^[1]; Schofield, Jeremy ^[2]

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1. Department of Chemistry, K. N. Toosi University of Technology, P.O. Box 15875-4416, Tehran (Iran, Islamic Republic of)
2. Chemical Physics Theory Group, Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario, Canada M5S 3H6 (Canada)

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.

• OSTI ID: 22658210
• Journal Information: Journal of Solid State Chemistry, Vol. 246; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
77 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