Density Functional Theory Study of Nitrogen Fixation Electrocatalysts Based on Two-Dimensional Conjugated Metal–Organic Frameworks

Creating high-performance single-atom catalysts for the electrochemical nitrogen reduction reaction (NRR) is a crucial approach. Two-dimensional metal–organic frameworks (MOFs) have captured significant attention as NRR catalysts due to their lightweight and large pores. Using density functional theory (DFT) calculations, we explored a series of TM 3 C 18 N 6 X 12 (X = S or NH, TM = Mo, Cr, W, Fe, Mn, Os, Ni, Ir, Pd, Pt, Rh) two-dimensional metal–organic frameworks (MOFs) as potential single-atom catalysts for NRR through a three-step screening strategy. The influence of coordinating atoms around transition metal atoms is also examined, specifically, TMS 4 or TMS 2 (NH) 2 . Our findings indicate that the Os 3 C 18 S 12 N 6 MOF exhibits the best activity and selectivity, with an overpotential of only 0.28 V along the distal pathway, which is lower than most reported MOF materials. The adsorption and activation of N 2 are influenced by the σ-acceptance-π* donation mechanism. Additionally, we established descriptors related to the valence electron (Δ Q TM X TM ) and magnetic moment (μ TM –μ X ) to explore the relationship between catalytic activity and descriptors. This work can offer valuable insights for designing promising electrocatalysts for NRR based on MOFs.