Onion-like Carbon (OLC), Iron, Cobalt and Nitrogen X-Ray Absorption Spectroscopy (XAS) Data Analysis

Abstract

This project was about analyzing the data of the X-Ray Absorption Spectroscopy (XAS) of several synthesis of modified Onion-like Carbon (OLC) nanoparticles with nitrogen conductive polymers to study different catalysts for the Oxygen Reduction Reaction (ORR). Also, observing differences in the oxidation state, geometry, iron and cobalt bonds, and structures between the samples at different potentials were some of the objectives in this investigation. The PyMca program was used to normalized the samples and transferred the scan’s data. In Athena for the X-Ray Absorption Near Edge Structure (XANES) region, the scans were merged for every sample individually by adjusting the pre-edge, post-edge, spline range in “k”, and the normalization order parameters. Subsequently, Artemis for the Extended X-Ray Absorption Fine Structure (EXAFS) region was used to fit the first and second shell of the samples used in Athena. Here we used a FEFF calculations file from a Cobalt Oxide and Iron Oxide compounds that have similar elements to the ones in our samples. As results, we have been able to fit the N-OLC/FeCo (1:3)-Co and N-OLC/FeCo(1:3)-Fe. In both cases the fits from the first shell were from Co-O and Fe-O bonding interactions and the fits from the second shell were from Co-Co and Fe-Fe bonding interactions between the atoms.