In-Silico Screening the Nitrogen Reduction Reaction on Single-Atom Electrocatalysts Anchored on MoS₂

Abstract

We show that a Single-Atom Electrocatalyst (SAC) for the Nitrogen Reduction Reaction (NRR) can provide an environmentally green alternative to the Haber–Bosch high-temperature high-pressure process, replacing the water gas shift production of H₂ with H extracted from water. Anchoring the single atom on a two-dimensional substrate provides control to tune NRR catalytic performance toward a SAC possessing high utilization, high activity, and high selectivity. Experimental results suggest that this can significantly improve the activity and selectivity of NRR, but the specific reaction mechanism remains uncertain. This makes it difficult to select new catalytic materials for further optimization. Here we use Density Functional Theory to study the NRR catalytic mechanism on a catalytic model using a MoS₂ substrate to support a single atom site. We correct for solvation effects on the electrochemical reactions. We started with Fe@MoS₂, for which there are promising experimental reports, and conducted a systematic study of the NRR reaction mechanisms. These results show that N₂ adsorption, hydrogenation of N₂, desorption of NH₃, and Hydrogen Evolution are all critical steps affecting the reaction rates. Based on these steps, we scanned 23 transition metal elements to find improved catalysts. We identified Ir@MoS₂ (Mo top site) as the best candidate, predicted to have good catalytic activity and selectivity with 64.11% Faraday Efficiency. These results on the mechanism for NRR and the in silico search for alternative catalysts provide new promising targets for synthesizing novel and efficient SAC@MoS₂ NRR catalysts.

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