Regulating the Coordination Environment of Single-Atom Catalysts Anchored on Thiophene Linked Porphyrin for an Efficient Nitrogen Reduction Reaction

The electrochemical nitrogen reduction reaction (NRR) offers a promising strategy to resolve high energy consumption in the nitrogen industry. Recently, the regulation of the electronic structure of single-atom catalysts (SACs) by adjusting their coordination environment has emerged as a rather promising strategy to further enhance their electrocatalytic activity. Herein, we design novel SACs supported by thiophene-linked porphyrin (TM-N4/TP and TM-N4-xBx/TP, where TM = Sc to Au) as potential NRR catalysts using density functional theory calculations. Among these catalysts, TM-N4/TP (TM = Ti, Nb, Mo, Ta, W, and Re) and TM-N4/TP with a water bilayer (TM = Nb, Mo, W, and Re) show excellent activity (low limiting potential) but low selectivity. Encouragingly, we find that Mo-N3B/TP, Mo- N2B2-2/TP, W-N3B/TP, W-N2B2-2/TP, Re-N3B/TP, Re-N2B2-2/TP, and Re-N2B2-1/TP serve as the most efficient NRR electrocatalysts, as they present stability, superior activity, better selectivity with low limiting potentials (-0.18 --0.90 V), and high Faradaic efficiencies (>99.80%). Based on microkinetic modeling, kinetic analysis of the NRR is performed and shows that the Re-N2B2-1/TP catalyst is more efficient for NH3 formation. Additionally, multiple-level descriptors provide insight into the origin of NRR activity and enable fast prescreening among numerous candidates. This work provides a new perspective to design highly efficient catalysts for the NRR under ambient conditions.