Two-dimensional π-conjugated osmium bis(dithiolene) complex (OsC4S4) as a promising electrocatalyst for ambient nitrogen reduction to ammonia

The electrochemical reduction of nitrogen (NRR) at ambient conditions is an appealing alternative to the industrial method for ammonia synthesis that requires high temperature and pressure, but its efficiency is greatly dependent on stable and efficient electrocatalysts. Hence, by means of comprehensive density functional theory (DFT) computations, we investigated the potential of a new class of metal-organic frameworks (MOF)-based catalyst for the NRR, namely, the synthesized π-conjugated metal bis(dithiolene) nanosheet (MC₄S₄, M = Fe, Co, Ni, Ru, Rh, Pd, Pt, Os, and Ir). Our results demonstrated that the NRR catalytic activity of MC₄S₄ is highly dependent on the central metal atom. Due to the low overpotential (0.31 V), the OsC₄S₄ nanosheet is predicted to exhibit outstanding NRR catalytic activity through the distal mechanism, in which the hydrogenation of the activated N₂ molecule to the N₂H* species is identified as the potential-determining step. Our work is the first report of 2D MOF-based electrocatalyst for N₂ reduction, opening a new avenue for advancing sustainable NH₃ synthesis under ambient conditions.