Screening Janus-2H-WSSe with Adsorbed Transition Metals as Efficient Catalyst for Nitrogen Reduction Reaction

Electrocatalytic nitrogen reduction reaction (NRR) provides a promising strategy for effective nitrogen fixation under mild conditions. Herein, structural stability and NRR catalytic activity of 29 transition metal (TM, Sc-Hg) atoms adsorbed Janus 2H-WSSe monolayers are studied using the first-principles calculations. Six screened TM@S/Se-WSSe (TM = Os, Re) and TM@Se-WSSe (TM = Ir, Mo) systems are considered promising single-atom catalysts (SACs) due to low limiting potential (-0.36 to -0.73 V) and high Faradaic efficiency (FE > 90.61%). High catalytic activity arises from the donation and back-donation mechanisms between the empty/unoccupied TM-d orbitals and the bonding/antibonding N₂-p orbitals, which significantly promote the activation of N₂ and the charge transfer in the subsequent hydrogenation reactions. In addition, the catalytic activity trend of the screened TM@WSSe systems is further analyzed by four descriptors (ΔG_*NNH, ΔG_*NH2, ΔG_*N, and φ). The high activity can be achieved by individually tuning ΔG_*NH2 or ΔG_*NNH. Meanwhile, the TM@WSSe with ΔG_*N = -1.38 eV and φ = 6 exhibits the best catalytic activity. The results provide insights into designing efficient nitrogen fixation electrocatalysts.