Single-atom catalytic N2 fixation with integrated descriptors on a novel π-π conjugated graphitic carbon nitride (g-C13N15) platform obtained by self-doping design: Prediction of ultrahigh activity and desirable selectivity

Great enthusiasm in nitrogen reduction reaction (NRR) towards the robust design of efficient catalysts is being stimulated by a promising active moiety featured by metal-Nx, yet tackling the activity and selectivity dilemmas remains one of the most urgent and challenging tasks. Herein, based on a self-doping strategy and first-principles calculations, an emerging and stable graphitic carbon nitride, g-C13N15, is rationally proposed for the first time, and TM@g-C13N15 (TM = from Ti to Au) single-atom catalysts benefiting from delocalized π−π conjugated interactions between substituted C3N3 rings toward NRR are constructed. High-throughput "Four-Step" screening strategy helps Re@g-C13N15 stand out from 23 TM-centers quickly since the binding strength of the target *N2H and *NH2 adsorbates can be manipulated by Re to compromise. First-principles calculations reveal that Re@g-C13N15 possesses satisfactory selectivity and impressively, miserly energy consumption with a low limiting potential of −0.20/-0.31 V for side-on/end-on N2-adsorption. Also, good thermodynamic stability, large Re-diffusion barrier, outstanding electrochemical durability, and facile synthesis for Re@g-C13N15 ensure its implementations in ambient conditions. Particularly, good linear relationships between descriptors (ICOHP, Bader charge, bond length, d-band center, and spin moment) are established to describe/explain intrinsic activity trends/mechanism, bridging the relation between the intrinsic property and activity.