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

Abstract

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 (CeO x ) demonstrate highly efficient activity and enhanced stability for ammonia electrolysis in a nonaqueous electrolyte system. The Faradaic efficiency of N 2 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 NH 3 adsorption and exhibits a significantly lower energy barrier for the initial step of NH 3 dissociation compared to CeO 2 . Consequently, this contributes to the heightened activity of ammonia electrolysis on the electrode of cerium oxide following the G− M mechanism.

CeO2/Ni Inverse Catalyst as a Highly Active and Stable Ru-free Catalyst for Ammonia Decomposition

“…The same finding was also observed in Ni/CeO 2 /Al 2 O 3 catalyst, as reported by Jia’s research group . Meanwhile, other work has also shown that CeO 2 with more vacancy sites is more favorable for the adsorption of ammonia and lowers the energy barrier for the initial step of ammonia dissociation . In addition, the I D / I F2g value of Ni/CeO 2 only showed a slight decrease at 400 °C (from 0.58 to 0.49) (Figure d), which can be ascribed to the lower oxygen vacancy content on the surface of Ni/CeO 2 , providing fewer sites for NH 3 adsorption than that of CeO 2 /Ni.…”