We systematically investigated the catalytic performance of 3d, 4d, and 5d transition metals anchored onto two-dimensional extended porphyrin (PP) substrates as nitrogen reduction reaction (NRR) electrocatalysts, employing density functional theory (DFT) calculations and four-step high-throughput screening. Four novel metalloporphyrin (MPP, M = Zr, Nb, Hf, and Re) single-atom catalyst candidates have been identified due to their excellent catalytic performance (low onset potential, high stability, and selectivity). Through comprehensive reaction path search, the maximum Gibbs free energy changes for NRR on the ZrPP (enzymatic-consecutive hybrid path), NbPP (consecutive path), HfPP (enzymatic-consecutive hybrid path), and RePP (distal path) catalysts are 0.38, 0.41, 0.53, and 0.53 eV, respectively. Band structures, projected density of states, and charge/spin distributions show that the high catalytic activity is due to significant orbital hybridizations and charge transfer between N₂ and MPP catalysts. We hope our work will promote experimental synthesis of these NRR electrocatalysts and provide new opportunities to the electrochemical conversion of N₂ to NH₃ under ambient conditions.

We for the first time systematically studied the structures and electrochemical nitrogen reduction reaction properties of two-dimensional single transition-metal anchored square tetracyanoquinodimethane monolayers (labeled as: TM-sTCNQ, TM = 3d, 4d, 5d series transition metals) by employing density functional theory method. Through high-throughput screenings and full reaction path researches, two promising electrochemical nitrogen reduction reaction catalysts Nb-sTCNQ and Mo-sTCNQ have been obtained. The nitrogen reduction reaction onset potential on Nb-sTCNQ is as low as −0.48 V. Furthermore, the Nb-sTCNQ catalyst can quickly desorb NH₃ produced with a free energy of 0.65 eV, giving Nb-sTCNQ excellent catalytic cycle performance. The high catalytic activity of the two materials might be attributed to the effective charge transfer between the active center and adsorbed N₂, which enables the active center to adsorb and activate inert N₂ molecules well, and the reduction processes require small energy input (i.e., the maximum free energy changes are small). This work provides insights for finding highly efficient, stable, and low-cost nitrogen reduction reaction electrocatalysts. We hope our results can promote further experimental and theoretical research of this field.