Engendering anion immunity in oxygen consuming cathodes based on Fe-N x electrocatalysts: Spectroscopic and electrochemical advanced characterizations

Abstract Oxygen reduction reaction (ORR) is the key reaction utilized for several potentially promising technologies such as in energy conversion (fuel-cells) or as oxygen depolarized cathodes (ODC) in anodic evolution of bulk chemicals such as chlorine. In the latter case elimination of one volt out of a theoretical maximum of 1.34 V (in case of hydrogen evolution electrode) provides very significant energy savings. Here we report iron based Fe-N x catalyst with promising activity compared to state of the art noble metal catalysts (Rh x S y ) for hydrochloric acid recovery systems. A combined electrochemical and synchrotron-based spectroscopic approach is used to probe the structural and elec tronic properties of the active centers. The surface sensitive delta-mu (Δm) analysis of the near edge X-ray absorption fine structure (NEXAFS), supported by first-principles calculations, reveals the immunity of the Fe-N x -C y active centers to chloride poisoning. Initial stability studies show that even after a harsh corrosive treatment, the catalyst ORR activity remains comparable to the current state of the art precious based material. Our study opens up promising avenues for developing affordable and robust oxygen consuming electrodes.