This project was about analyzing the data of the X-Rays Absorption Spectroscopy of several synthesis of modified onion-like carbon nanoparticles with and without nitrogen conductive polymers to study different catalysts for the oxygen reduction reaction. Also, observing differences in the oxidation state, geometry, iron and cobalt bonds, and structures between the samples were some of the objectives in this investigation. For this, PyMca was used to normalize the samples and transferred the scan’s data to excel. In Athena for the 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 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 (II) acetylacetonate complex that have similar elements than the one in our samples. As results, we have been able to fit 3 samples, which are the N-OLC/Co, OLC/FeCo (1:3)-Co and OLC/Co. In every sample when they were fitted, the fits from the second shell looks a little bit off comparing them to the first shell. A possible explanation can be that in that region of the second shell the interactions of bonding atoms are not from Cobalt to Oxygen and it is possible that they are from Cobalt to Cobalt. To prove that we need to try some new fitswith a FEFF file from a molecule or complex with this type of interaction.

Onion-like carbon, iron, cobalt and nitrogen XAS data analysis

ACS Spring 2022

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