Dual-Atomic Porphyry Molecular Systems as Efficient Electrocatalysts for N2 Reduction Reaction: a Theoretical Investigation

Abstract

Metallo-porphyry-based frameworks have been utilized to construct single-atom catalysts (SACs), but their use in the fabrication of dual-atom catalysts (DACs) for the nitrogen reduction reaction (NRR) electrocatalytically is limited. Herein, a binuclear phthalocyanine (bN-Pc) was assessed based on a theoretical model to construct dual-atom systems (MoMo-bN-Pc, WW-bN-Pc, and MoW-bN-Pc) along with NRR activity and respective mechanisms, exploiting density functional theory (DFT) calculations. A cis-bridged N₂-adduct, with N-atoms coordinating on both sides, resulted in these dual-atom systems, keeping adjacent metals in close proximity. Gibbs free energy studies revealed that the potential-determining step (PDS) for these catalysts appeared to be the protonation of adsorbed N₂ on dual-atom sites (*N₂H). Following the enzymatic pathway, MoW-bN-Pc had the lowest limiting potential (− 0.32 V) than other systems, indicating its higher NRR activity. The synergistic orbital coupling between Mo(4d) and W(5d) due to their intimate proximity significantly raised the energy of the highest occupied molecular orbital of Mo to facilitate the electron donation to the antibonding orbital of N₂, endowing the NRR of MoW-bN-Pc as compared to other systems. This work is sure to create interest for future studies on the construction of DAC-based active sites using molecular models.