Investigation of Chloride Poisoning Resistance for Nitrogen-Doped Carbon Nanostructures as Oxygen Depolarized Cathode Catalysts in Acidic Media

Abstract

HCl electrolysis used to manufacture Cl2, a compound of high industrial value, suffers from its high energy requirements. Significant energy savings can be attained by an alternative oxygen depolarized cathode (ODC)-based process where oxygen is reduced at the cathode instead of protons. Though the ODC process is extremely attractive, the state of the art catalysts for oxygen reduction reaction (ORR) suffer from chloride ion poisoning and/or involve toxic chemicals such as hydrogen sulfide (H2S). In the present work, we demonstrate that non-metal containing CNx catalysts do not get deactivated upon exposure to chloride ion environment unlike Pt/C or RhxSy/C where significant chloride ion poisoning was observed. The synthesis of these CNx materials is also extremely facile and scalable. In addition, the performance of the synthesized CNx catalysts was found to be very stable in HCl environment. Thus, the results presented here demonstrate the promise of CNx materials as alternative catalysts for ODC-based HCl electrolysis process to manufacture Cl2 in a sustainable and safer way.