Abstract
To investigate the precursors and growth mechanisms of two-dimensional C(x)N(y) materials, we performed laser ablation mass spectrometry and spectroscopy on graphitic carbon nitride. A series of clusters, [(C(2)N(3))(n)H(n-1)](-) (n = 1-4), were identified, with C(2)N(3) (-) as the dominant species. Structural analyses indicate that C(2)N(3)H is a linear molecule containing cyanide and carbodiimide groups, whereas C(2)N(3) (-) corresponds to a dicyanamide anion. Their reaction sites, characterized by a three-center four-electron motif and electron delocalization, promote polymerization. C(4)N(6)H(-) forms via C(2)N(3)H + C(2)N(3) (-) coupling, and C(6)N(9)H(2) (-) is generated through a two-step cyclization involving two C(2)N(3)H and one C(2)N(3) (-). Theoretical results predict that fused-ring C(8)N(12)H(3) (-) can evolve from C(4)N(6)H(-) with two C(2)N(3)H, or from C(6)N(9)H(2) (-) with one C(2)N(3)H. This progression from linear to branched, cyclic, and fused-ring clusters parallels g-C(3)N(4) growth, suggesting a synthesis route for 2D C(x)N(y) materials and providing insights for detecting nitrogen-rich carbon clusters in interstellar space.