Electronic Properties Of Pure Research Articles

Electronic Properties of Pure and Fe-Doped β-Ni(OH)2: New Insights Using Density Functional Theory with a Cluster Approach

NiOx has recently emerged as a robust catalyst with high catalytic activity for water oxidation reaction. Despite extensive studies, the origin of the high oxygen evolution reaction activity upon Fe doping is not fully solved, even for one of its simplest phases, β-Ni(OH)2. We present here density functional theory calculations using for the first time a cluster approach to revisit the electronic structure of pure and Fe-doped β-Ni(OH)2. First, our findings agree with a recent hypothesis that the band gap of the pure case reduces upon Fe doping. Second, in agreement with earlier calculations, we find that the highest occupied state consists of O and Ni states in pure and Fe-doped β-Ni(OH)2. However, the lowest unoccupied orbitals are Ni and O for pure β-Ni(OH)2 and mainly Fe for Fe-doped β-Ni(OH)2. We argue that the two different states for the highest occupied state and for the lowest unoccupied state of Fe-doped β-Ni(OH)2 may lead to low electron–hole recombination. Third, the delocalized nature of the ...

Investigations on the Structural and Electronic Properties of Pure and Doped Bulk Pr2NiO4 through First Principles Calculations

Pr2NiO4-based ceramic oxides are known promising MIEC cathodes material for SOFC, owing to its experimentally found good ionic and electronic conductivity compared with other known materials. In this study, the structural and electronic properties of pure and doped Pr2NiO4-based oxides are investigated through first principles calculations based on density functional theory (DFT) in an attempt to investigate the possibility of using this material as an SOFC electrolyte. Substitutional doping at the cation site [Pr2-yRyNi1-x-y-zExTzO4 (R=La, and E=Cu and T=Ga)] shows change in both structural and electronic properties. Higher concentration of La doping increases the lattice parameter along the c direction while maintaining the electronic property of the host system. On the other hand, Cu doping causes tilting of the nickelate octahedral substructures so as to stabilize the whole structure but accompanies emergence of states which can contribute to electronic conduction. However, Ga doping has indications of high O ion diffusion and lower electronic conductivity

Thermodynamic Reconsiderations on Electronic Properties of Pure- and Doped-Ceria

Reconsiderations have been made on the electronic properties of pure- and doped ceria on the basis of the energetic scheme which has been considered to take into account the regularity of the hole conductivity in rare earth doped ceria as well as the anomalous behavior of hole conductivity of nano-derived Gd-doped ceria; this assumes the constituent of Ce3+O2-O-, in other words, the electron-pair formation. To interpret the plateau found in our recent experiment on electron conductivity of pure ceria, the electron concentration has been calculated for the formation of electron-hole pairs with those data for Ce3+O2-O-. Calculated electron concentrations can reproduce essentially the same behavior as those in electron conductivity. Further considerations have been made on why the anomalous hole conductivity appeared only when the nano-powder derived GDC samples were polarized.

Thermodynamic Reconsiderations on Electronic Properties of Pure- and Doped-Ceria

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