Crystal structure, electrical and electrochemical properties of Cu co-doped Pr1.3Sr0.7NiO4+δ mixed ionic-electronic conductors (MIECs). (4th January 2018)

• Record Type: Journal Article
• Authors: Bansod, M.B.; Khandale, A.P.; Kumar, R.V.; Bhoga, S.S.
• Is Part Of: International journal of hydrogen energy. Volume 43:Number 1(2018)
• Page Start: 373
• Page End: 384
• Publication Date: 2018-01-04
• Subjects: Mixed ionic electron conductor -- Co-doping -- Electrical conductivity -- Crystal structure -- Ionic conductivity of cathode; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2017.11.005
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: Room temperature crystal structure, electrical properties and electrochemical properties in the temperature range 25–700 °C of Cu co-doped Pr1.3 Sr0.7 NiO4+ δ prepared by acetate combustion is investigated from intermediate temperature solid oxide fuel cell cathode viewpoint. The Pr1.3 Sr0.7 Ni1−x Cux O4+ δ (PSNCO) solid solutions have a tetragonal I 4 /mmm K2 NiF4 -type structure which consists of a (Pr1.3 Sr0.7 ) (Ni1.x Cux )O3 perovskite unit and a (Pr1.3 Sr0.7 )O rock salt unit in the whole compositional range 0 ≤ x ≤ 0.4. A reduction in bond-length of Ni/Cu-O resulting from PSNCO lattice contraction eases hop of small polaron from Ni 3+ to Ni 2+ /Cu 2+ in (Ni1−x Cux )-O layer with low activation energy, which increases electron conductivity. The maximum electronic conductivity ( σ = Ω cm −1 ) with minimum activation energy ( E a = eV) is observed at x = 0.3. Lattice expansion along c -direction owing to Cu 2+ doping facilitates hop of O 2− from its occupied interstitial site (O3 ) to nearby equivalent site assisted by anisotropic thermal motion of apical oxygen O2 resulting in increase in ionic conductivity. The minimum polarization resistance value ( R p = 0.13 (2) Ω cm 2 ) and activation energy ( E a = 1.321 (5) eV) at x = 0.3 is attributed to high electronic and ionic conductivities compared to other compositions. Complex impedance spectroscopy studies suggest that the ORR is co-limited by O 2− diffusion and O2 surface exchange. Graphical abstract: Highlights: Cu co-doped Pr1.3 Sr0.7 NiO4+ δ synthesized by combustion yield super fine crystallites. Lattice contraction along a - b directions by co-doping facilitates small polaron hopping. Surface oxygen exchange reaction increases with Cu doping. CIS study suggests ORR is co-limited by O 2− diffusion and O2 surface exchange.