Paper on Co-Mn Spinels Published in J. Phys.: Condensed Matter

Our team’s paper, led by Miles Blanchet and Ryan Comes at Auburn University, has just been published in the Journal of Physics: Condensed Matter! In this paper we explore the site-occupancy of CoMn2O4 spinels, identifying pathways for the accommodation of excess Co. These results provide fundamental insight into synthesis and behavior of an important class of materials for oxygen reduction catalysis.

From the abstract:

Recent investigations on spinel CoMn2O4 have shown its potential for applications in water splitting and fuel cell technologies as it exhibits strong catalytic behavior through oxygen reduction reactivity. To further understand this material, we report for the first time the synthesis of single-crystalline Co1+xMn2-xO4 thin films using molecular beam epitaxy. By varying sample composition, we establish links between cation stoichiometry and material properties using in-situ x-ray photoelectron spectroscopy, x-ray diffraction, scanning transmission electron microscopy, x-ray absorption spectroscopy, and spectroscopic ellipsometry. Our results indicate that excess Co ions occupy tetrahedral interstitial sites at lower excess Co stoichiometries, and become substitutional for octahedrally-coordinated Mn at higher Co levels. We compare these results with density functional theory models of stoichiometric CoMn2O4 to understand how the Jahn-Teller distortion and hybridization in Mn-O bonds impact the ability to hole dope the material with excess Co. The findings provide important insights into CoMn2O4 and related spinel oxides that are promising candidates for inexpensive oxygen reduction reaction catalysts.

To view the manuscript, visit: https://iopscience.iop.org/article/10.1088/1361-648X/abd573

To download the manuscript directly, click here.