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SUMMARY:DFT study of oxygen vacancies in pure and doped ceria for chemical
  looping reforming - Dr Rachel Kerber (Grey Group)
DTSTART:20160506T110000Z
DTEND:20160506T114000Z
UID:TALK65738@talks.cam.ac.uk
CONTACT:Alex Thom
DESCRIPTION:Chemical Looping represents a promising new technology for ach
 ieving cheap and efficient\nseparation of CO2 in energy generation process
 es. The chemical looping technique is based on the redox cycle of an oxyge
 n carrier\, usually a transition metal oxide\, which reacts endother- mica
 lly with a fuel\, according to:\n(2n + m)MyOx + CnH2m → (2n + m)MyOx−1
  + mH2O + nCO2. (1) The reduced metal oxide is then transferred to the air
  reactor where it is oxidised by the\nhighly exothermic reaction:\nMyOx−
 1 + 1O2 → MyOx\, (2) 2\nwhere n\, m\, x and y are stoichiometric coeffic
 ients.\nSpin-polarized Density Functional Theory (DFT) calculations were p
 erformed for geometry optimization of ceria in Vienna Ab-initio Simulation
  Package (VASP) using the range sepa- rated hybrid functional HSE06 and GG
 A+U (PBE+U)\, where both methods are appropriately applied.[1] PBE+U was s
 hown to accurately describe the electron localisation of the system while 
 only calculating qualitatively correct energy differences\, while the hybr
 id functionals (HSE) were considered a better choice to calculate both the
  lattice parameters and electronic properties (band gaps and density of st
 ates (DOS)) of such materials.\nThe Fe-doped and Zn-doped cerium oxides we
 re studied to increase the oxygen vacancy con- centration and concomitant 
 oxide ion conductivity in CeO2 by Ce+4/Ce+3 substitution with metal ions o
 f a lower valence.[2]\,[3] The effect of oxygen vacancies and different do
 pants on ceria will be discussed.\n\nReferences\n[1] Ganduglia-Pirovano M.
  V.\, L. F. Da Silva J.\, and Sauer J.\, Phys. Rev. Lett. 102 (2009)\, 026
 101.\n[2] Farra R.\, Garc ́ıa-Melchor M.\, Eichelbaum M.\, Hashagen M.\,
  Frandsen W.\, Allan J.\, Girgsdies F.\,\nSzentmiklósi L.\, López N.\, a
 nd Teschner D.\, ACS Catal. 3 (2013)\, 2256.\n[3] Aryanpour M.\, Khetan A.
 \, and Pitsch H.\, ACS Catal. 3 (2013)\, 1253.
LOCATION:Unilever Lecture Theatre\, Department of Chemistry
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