Hierarchical Phosphorene Growth Pathway Mediated by Competing P-Cu and P-P Interactions.

While recent breakthroughs have demonstrated blue phosphorene (BlueP) on Cu(111), its growth mechanism remains elusive, owing to strong P-Cu coupling. Through scanning tunneling microscopy, we reveal a hierarchical growth pathway mediated by competing P-Cu and P-P interactions. At low coverage, strong P-Cu bonding dominates, leading to the formation of P clusters, subsequently developing a distorted 1 × 1 chain structure. Continuously increasing P density triggers a structural transition to a near 1 × 1 stripe phase, facilitated by partial interchain bonding and complete P-P coordination. Upon reaching saturation coverage, an enhanced P-P interaction drives the system to ultraflat 1 × 1 BlueP. Crucially, we reveal that interfacial charge transfer monotonically decreases and P-P bonding energy strengthens with increasing coverage, highlighting a shift in the dominant interactions from P-substrate bonding to intralayer stabilization. This reversal of interaction hierarchy, from substrate-dominated to intralayer-dominated bonding, establishes a universal kinetic pathway for fabricating non-van der Waals two-dimensional materials on reactive metal substrates.