Anion-Deficient Transition Metal Oxynitrides as Anode Materials for Solid Oxide Fuel Cells.

Abstract

Transition metal oxynitrides, with their unique electronic structures and excellent conductivity, hold significant promise as anode materials in fuel cells. In this study, we synthesized and characterized two novel anion-deficient transition metal oxynitrides: Ca₄La₈V₄O₈N₁₂ and Sr₃La₉V₄O₇N₁₃. Their crystal structures were determined via Rietveld refinement of X-ray and neutron diffraction data, revealing a higher concentration of anion vacancies in Sr₃La₉V₄O₇N₁₃. As a result, Sr₃La₉V₄O₇N₁₃ exhibits significantly enhanced electrical conductivity compared to Ca₄La₈V₄O₈N₁₂. Density functional theory (DFT) calculations indicate that Sr₃La₉V₄O₇N₁₃ possesses higher defect formation energies, influencing its band structure and facilitating electron transitions, thereby enhancing conductivity. This study underscores the role of anion deficiencies in modulating the electronic properties of transition metal oxynitrides and offers new insights for designing high-performance anode materials for solid oxide fuel cells (SOFCs).