Remarkable performance of triatomic single-cluster catalyst of Ti3@graphdiyne in electrocatalytic nitrogen reduction

The electrocatalytic nitrogen reduction reaction offers a sustainable route for unconventional ammonia synthesis, yet its practical implementation is often hindered by catalyst performance. Herein, by using first-principles calculations, we systematically explore the eNRR performance of a series of single-cluster catalysts with monometallic triatomic clusters of 3d transition metals anchored on graphdiyne (TM3/GDY, TM = Sc-Zn). The Ti3/GDY, V3/GDY, Cr3/GDY, and Mn3/GDY all exhibit robust stability and feature spontaneous N2 chemisorption and significant N≡N bond activation (elongation > 0.14 Å). Chemical bonding analysis uncovers σ-π synergistic donor-acceptor interactions between TM-3d orbitals and N2 π* antibonding states as the origin of superior catalytic activity. Ti3/GDY achieves a low limiting potential of -0.39 V while effectively suppressing N2H4 formation. This dual advantage stems from its elevated d-band center and high charge transfer. The titanium-based triatomic architecture is found to be a promising candidate for sustainable nitrogen fixation. This work offers a fundamental design principle for SCCs through atomic-level coordination engineering and electronic structure modulation.