Jury’s and Stephen’s paper on the mechanisms of major pathways of urea electro-oxidation and approaches to steer the reaction selectivity is published in the Angewandte Chemie, congratulations Stephen, Jury, Feng and Yulia!
Nickel-Catalyzed Urea Electrolysis: From Nitrite and Cyanate as Major Products to Nitrogen Evolution
The electrochemical urea oxidation reaction (UOR) to N2 represents an efficient route to simultaneous nitrogen removal from N-enriched waste and production of renewable fuels at the cathode. However, the overoxidation of urea to NOx¯ usually dominates over its oxidation to N2 at Ni(OH)2 -based anodes. Furthermore, detailed reaction mechanisms of UOR remain unclear, hindering the rational catalyst design. We found that UOR to NOx¯ on Ni(OH)2 is accompanied by the formation of near stoichiometric amount of cyanate (NCO¯), which enabled the elucidation of UOR mechanisms. Based on our experimental and computational findings, we show that the formation of NOx¯ and N2 follows two distinct vacancy-dependent pathways. We also demonstrate that the reaction selectivity can be steered towards N2 formation by altering the composition of the catalyst, e.g., doping the catalyst with copper (Ni0.8Cu0.2(OH)2 ) increases the faradaic efficiency of N2 from 30% to 55%.