1. Cation doping and oxygen vacancies in the orthorhombic FeNbO4 material for solid oxide fuel cell applications: A density functional theory study.
- Author
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Wang, Xingyu, Santos-Carballal, David, and de Leeuw, Nora H.
- Subjects
SOLID oxide fuel cells ,DENSITY functional theory ,CONDUCTION electrons ,HYDROGEN oxidation ,DENSITY of states - Abstract
The orthorhombic phase of FeNbO
4 , a promising anode material for solid oxide fuel cells (SOFCs), exhibits good catalytic activity toward hydrogen oxidation. However, the low electronic conductivity of the material specifically in the pure structure without defects or dopants limits its practical applications as an SOFC anode. In this study, we have employed density functional theory (DFT + U) calculations to explore the bulk and electronic properties of two types of doped structures, Fe0.9375 A0.0625 NbO4 and FeNb0.9375 B0.0625 O4 (A, B = Ti, V, Cr, Mn, Co, Ni) and the oxygen-deficient structures Fe0.9375 A0.0625 NbO3.9375 and FeNb0.9375 B0.0625 O3.9375 , where the dopant is positioned in the first nearest neighbor site to the oxygen vacancy. Our DFT simulations have revealed that doping in the Fe sites is energetically favorable compared to doping in the Nb site, resulting in significant volume expansion. The doping process generally requires less energy when the O-vacancy is surrounded by one Fe and two Nb ions. The simulated projected density of states of the oxygen-deficient structures indicates that doping in the Fe site, particularly with Ti and V, considerably narrows the bandgap to ∼0.5 eV, whereas doping with Co at the Nb sites generates acceptor levels close to 0 eV. Both doping schemes, therefore, enhance electron conduction during SOFC operation. [ABSTRACT FROM AUTHOR]- Published
- 2024
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