Catalyst poisoning influences from various functional groups of energy carriers towards electrochemical oxidation reactions on non-noble high-entropy alloy anodes in acidic media

Tahawy Rafat, Muflihah Salma Aridha, Hara Kosuke, Ohto Tatsuhiko, Tanimoto Hisanori, Li Tianshu, Abdelnabi Mahmoud, Samuel Jeong, Nishiuchi Tomohiko, Kimizuka Hajime, Aimon Akfiny Hasdi, Yoshikazu Ito

Electrolytic synthesis of energy carriers using renewable energy and fuel cells that use energy carriers for regeneration are important technologies for achieving our carbon-neutral society. However, electrochemical reactions in electrolyte containing organic molecules significantly degrade the electrodes by catalyst poisoning (i.e. polymerization of organic molecules on the electrode surface). Such a situation can easily occur through the crossover phenomenon between the anode and cathode chambers. Thus, the understanding of the electrochemical reactivity of organic molecules on electrodes becomes important for utilizing energy carriers. This study investigated the electrochemical reactivity of various organic molecules with typical functional groups to understand the reaction mechanism and the subsequent catalyst poisoning in acidic media. While -OH groups on organic molecules do not cause significant degradations on a non-noble metal high-entropy alloy anode, the coexistence of -NH2 and C=O groups on organic molecules significantly degrades the anode because the generated polymers block the catalytically active sites. This knowledge will contribute to the effective design of catalysts/electrodes and benefit the communities in electrolytic synthesis and fuel cells. [GRAPHICS]