Design of a High-Performance Electrocatalyst for N₂ Conversion to NH₃ by Trapping Single Metal Atoms on Stepped CeO₂

Single-atom catalysts (SACs) have recently been shown to have high performance in catalyzing the synthesis of NH₃ from N₂. Here, we systematically investigated a series of single transition metal atoms anchored on stepped CeO₂ (CeO₂-S) to screen the potential electrocatalysts for a N₂ reduction reaction (NRR) via density functional theory computations. We first demonstrated that these SACs are stable via large calculated binding energies. Second, we evaluated the adsorption of *N₂ over CeO₂-S-supported single atoms. Here, those systems that can activate N₂ molecules were selected as candidates. We then showed that CeO₂-S-supported single Mo and Ru atoms have high catalytic activity for NRR via low limiting potentials of -0.52 and -0.35 V, respectively. Meanwhile, the competitive hydrogen evolution reaction is highly suppressed over these two SACs because the adsorption of *N₂ is prior to *H. Finally, the origin of the NRR activity over these SACs was investigated. This work offers useful insights into designing high-performance CeO₂-based electrocatalysts for NRR.