Ligands dependent electrocatalytic nitrogen reduction performance in d-p conjugated molecules

The coordination environment of metal atoms in single-atom catalysts (SACs) has a greater impact on the catalytic performance of electrocatalysts. However, the influence mechanism of interacting ligands on the electrocatalytic nitrogen reduction reaction (NRR) process is still insufficient. Herein, by means of large-scale density functional theory (DFT) computations, the effect of organic ligands on the NRR process is investigated in-depth using half organometallic sandwich molecular SACs, i.e. TMBzs and TMCps (Bz = benzene, Cp = cyclopentadienyl, and TM = transition metal). The results revealed that the NRR performance of all the systems is highly dependent on the choice of d-pi interaction within the TM-Ligand complexes. Compared with TMBzs, the TMCps exhibit outstanding NRR activity and significantly suppress HER. Among 16 candidates, CrCp and MnBz are the most promising candidates with an ultra-low limiting potential of-0.29 V and-0.37 V via consecutive mechanism, respectively. Moreover, the systems with higher spin polarizations have better NRR activity. The work provides new insight into the NRR to molecular SACs with different organic ligands.