Facet dependence forCeO2as a potential Ammonia oxidation electrocatalyst studied by DFT

The transition toward a carbon-free energy system requires energy carriers that are both sustainable and practical to scale. Ammonia is a promising candidate due to its high energy density, established infrastructure, and compatibility with renewable electricity. A key challenge in direct ammonia fuel cells development is the lack of inexpensive, active, and poison-resistant anode catalysts capable of efficiently carrying out the ammonia oxidation reaction (AOR). Ceria () related materials have shown potential for AOR and adjacent reactions, however, a comprehensive mechanistic understanding of AOR on pristine ceria surfaces has not previously been established. This density functional theory study examines(111),(110), and(100) for AOR.(100) was found to be the most active surface with the least positive limiting potential of 1.16 V and a potential determining step (PDS) offor the Gerischer-Mauerer mechanism, whereas the Oswin-Salomon mechanism has a more positive limiting potential of 1.33 V due to the PDS being. In comparison,(111) and(110) possessed limiting potentials of 1.38 V and 1.33 V respectively, both with a PDS offor the Gerischer-Mauerer and Oswin-Salomon mechanisms. Among oxide materials, the activity of(100) is improved over NiO due to possessing a lower limiting potential for AOR. Introducing vacancies intomay further improve its activity toward AOR.