Modeling and calculations play a crucial role in applied materials research by providing the link between the property of the material and its atomic-scale structure. First-principles calculations can provide a link between the synthesis conditions and catalyst structure or the activity of the catalyst and the atomic-scale structure of its active sites. Although extensive previous research has shed light on some aspects of ORR activity and durability of PGM-free catalysts consisting of a transition metal, nitrogen, and carbon (M-N-C), detailed fundamental understanding of the structure-activity relationship is one of the most critical challenges that we face currently. This lack of detailed understanding of the nature of the M-N-C electro-catalysts hinders any rational improvements in their efficiency and durability. One of the challenges that need to be addressed in this effort is linking the first principle calculations with precise structural analysis and electrochemical studies to identify realistic theoretical models/structures.

Density functional theory (DFT) calculations have become crucial in the accurate interpretation of the spectroscopic features of materials obtained by advanced spectroscopic techniques such as X-ray photoelectron spectroscopy (XPS) and Mössbauer spectroscopy (MBS). Namely, structure-to-property relationships in catalytic materials are usually established through correlations of observed catalytic activity and structural data obtained by the surface sensitive spectroscopic methods. This is a challenging task that has recently become more feasible by coupling first principle calculations on model systems and spectroscopic measurements performed with real catalysts [1,2]. In this talk, we will discuss how DFT calculations of spectroscopies properties for well-defined defects of M-N-catalysts can facilitate the interpretation of XPS and MBS. These two methods are the primary surface analysis techniques for determining the chemical environment and coordination of nitrogen and transition metal (Fe) in these materials. Therefore, linking DFT modeling and ex situ and in situ spectroscopy might be a key to understanding the interplay between chemistry, morphology, and catalytic activity in M-N-C catalysts.

[1] K. Artyushkova, I. Matanovic, B. Halevi, P. Atanassov, Oxygen Binding to Active Sites of Fe-N-C ORR Electrocatalysts Observed by Ambient-Pressure XPS, J. Phys. Chem. C 2017, 121(5): 2836-2843.

[2] I. Matanovic, K. Artyushkova, M. B. Strand, M. J. Dzara, S. Pylypenko, P. Atanassov, Core Level Shifts of Hydrogenated Pyridinic and Pyrrolic Nitrogen in the Nitrogen-Containing Graphene-Based Electrocatalysts: In-Plane vs Edge Defects, J. Phys. Chem. C 2016, 120(51), 29225-29232.