Vacancy-Driven Ammonia Electrooxidation Reaction on the Nanosized CeOx Electrode in Nonaqueous Electrolyte

The vacancy-engineering strategy has been successfully employed for electrochemical conversion by modulating the electronic structure and reaction kinetics of metal oxide-based electrode materials. The electrolysis of ammonia into hydrogen and nitrogen under mild conditions would be beneficial for utilizing ammonia as a zero-carbon fuel for mobile applications, such as cars and ships. Although platinum has been studied as the most effective state-of-the-art electrocatalyst for ammonia electrolysis, its high cost and rapid deactivation due to nitride poisoning make it difficult to be used commercially. Herein, we report that nanosized cerium oxides (CeOx) demonstrate highly efficient activity and enhanced stability for ammonia electrolysis in a nonaqueous electrolyte system. The Faradaic efficiency of N2 is approximately double that of a commercial Pt/C electrode, while its onset potential is lower than that of the latter. Cerium oxide with vacancy sites was found to be more favorable for NH3 adsorption and exhibits a significantly lower energy barrier for the initial step of NH3 dissociation compared to CeO2. Consequently, this contributes to the heightened activity of ammonia electrolysis on the electrode of cerium oxide following the G–M mechanism.