The Orbital Nature of Electron Holes in BaFeO3 and Implications for Defect Chemistry

• DOI: 10.1021/acs.jpcc.2c02545
• Publication Date: 2022-07-21T11:53:08Z
• Authors: M. F. Hoedl; C. Ertural; R. Merkle; R. Dronskowski; J. Maier
• Keywords: 02 engineering and technology; info:eu-repo/classification/ddc/530; 0210 nano-technology; 530

Understanding the nature of electron holes in mixed protonic–electronic conducting perovskites is key to successful development novel electrode materials for protonic ceramic fuel and electrolyzer cells (PCFCs). Here, we use density functional theory investigate orbital interactions defect chemistry BaFeO3−δ─a model material more complex cation stoichiometries used PCFCs. The calculations revealed BaFeO3−δ be a negative charge-transfer with dominating d5L ( L = ligand hole) configuration. Chemical bonding analysis using projected Crystal Orbital Hamilton Population (COHP) further showed that are partially delocalized pdσ* bonds an approximately 80% share at oxygen ions. BaFeO3 was explored respect vacancies defects. vacancy formation energy increases decreasing hole concentration due rising Fermi level which electrons from removed accommodated. This effectively outweighs concomitant decrease Fe–O bond strength evidenced by energy-integrated COHP analysis. dissociative H2O absorption studied, where OH– fills H+ attached regular ion. this reaction becomes concentration. trend largely reflects favorable affinity