High-Throughput Screening of a Single-Atom Alloy for Electroreduction of Dinitrogen to Ammonia

Exploring electrocatalysts with high activity, selectivity, and stability is essential for the development of applicable electrocatalytic ammonia synthesis technology. By performing density functional theory calculations, we systematically investigated the potential of a series of transition-metal-doped Au-based single-atom alloys (SAAs) as promising electrocatalysts for nitrogen reduction reaction (NRR). The overall process for the Au-based electrocatalyst suffers from the limiting potential arising from the first hydrogenation step of the reduction of *N-2 to *NNH. However, SAAs showed to be favorable toward lowering free energy barriers by increasing the binding strength of N-2. According to simulation results, three descriptors were proposed to describe the first hydrogenation step Delta G(*N-2 -> *NNH): Delta G(*NNH), d-band center, and d/root E-m. Eight doped elements (Ti, V, Nb, Ru, Ta, Os, W, and Mo) were initially screened out with a limiting potential ranging from -0.75 to -0.30 V. Particularly, Mo- and W-doped systems possess the best activity with a limiting potential of -0.30 V each. Then, the intrinsic relationship between the structure and potential performance was analyzed using machine learning. The selectivity, feasibility, and stability of these candidates were also evaluated, confirming that SAA containing Mo, Ru, Ta, and W could be outstanding NRR electrocatalysts. This work not only broadens our understanding of SAA application in electrocatalysis, but also leads to the discovery of novel NRR electrocatalysts.

Automated summary

Exploring high-activity, selective, and stable electrocatalysts is crucial for electrocatalytic ammonia synthesis. Transition-metal-doped Au-based single-atom alloys (SAAs) were identified as promising candidates for nitrogen reduction reaction (NRR) due to their ability to lower free energy barriers. Initial screening revealed Mo and W-doped systems as having the best activity in terms of limiting potential.