Screening Antimonene-Based Single-Atom Catalysts for Nitric Oxide Electroreduction to Ammonia by Density Functional Theory Computations

Abstract

The electrochemical nitric oxide reduction reaction (NORR) offers a sustainable pathway to simultaneously convert toxic nitric oxide (NO) into valuable ammonia (NH3). However, the development of efficient electrocatalysts remains challenging due to the complex reaction pathways and competing side reactions. Herein, we conducted a high-throughput density functional theory (DFT) screening of single-atom catalysts embedded in two-dimensional antimonene (SACs/Sb) to assess their intrinsic NORR activity. Three candidates (Cu, Ag, and Au) with limiting potentials below –0.40 V were identified as highly promising NORR catalysts, among which Au exhibited the highest catalytic activity due to its lowest limiting potential (–0.24 V). Furthermore, competing processes such as the hydrogen evolution reaction and the formation of nitrogen-containing by-products are markedly suppressed, thereby affording high NH3 selectivity. The exceptional NORR performance of Au/Sb can be attributed to its appropriately moderated NO adsorption energy, resulting from the downshifted d-band center of the Au sites relative to the Fermi level. Additionally, by employing the Sure Independence Screening and Sparsifying Operator (SISSO) method, a predictive formula was further developed to evaluate the adsorption free energy of *NO, with the d-band center and charge transfer as universal descriptors. These results deliver fundamental insights into the structure–performance relationship of NORR catalysts, thereby guiding the rational design of next-generation electrocatalysts for NO-to-NH3 conversion.