First-Principles Evaluation of Proton Hopping in Tetrahedral Oxide Motifs

Area of Science:

• Materials Science
• Computational Chemistry
• Energy Conversion Technologies

Background:

• Proton-conducting oxides (PCOs) are crucial for energy conversion, but their optimization is complex.
• Current PCO research often involves intricate perovskite oxides requiring doping and alloying.
• The vast chemical diversity in oxides challenges efficient materials design.

Purpose of the Study:

• To establish a simplified materials motif database for understanding proton kinetics in oxides.
• To elucidate the fundamental relationship between materials chemistry and proton conductivity.
• To enable rational design and rapid screening of novel PCOs.

Main Methods:

• Utilized a computational approach focusing on the zincblende structure as a proxy for tetrahedral metal-oxide coordination.
• Systematically quantified the impact of cation type, oxidation states, and M-O bond lengths on proton hopping barriers.
• Mapped identified cation-geometry combinations onto existing materials databases (ICSD, Materials Project).

Main Results:

• Identified that strong M-O bonds and metal cations with large, variable oxidation states (e.g., Mo6+, V5+) correlate with lower proton hopping barriers.
• Successfully identified real materials containing predicted metal-oxide units within existing databases.
• Demonstrated good agreement between calculated proton hopping barriers in real structures and predictions from the motif database.

Conclusions:

• The simplified motif model provides a valuable first step towards the rational design of energy-efficient PCOs.
• The findings facilitate a quicker screening process for potential PCO candidates.
• Acknowledged model limitations and outlined future extensions for enhanced predictive accuracy.