Evolution of Hierarchically Layered Cu-Rich Silicide Nanoarchitectures

A solution-based synthesis of well-ordered Cu-rich silicide nanoarchitectures, consisting of a pair of layered cups and stems (ρ-Cu15Si4), is demonstrated. The as-grown ρ-Cu15Si4 typically exhibits distinct interconnected 1D stems consisting of a stack of nanorods (∼300 nm in length) terminated with concave hexagonal 3D cups that evolve through a self-regulated layer-by-layer growth mechanism. Discrete-time ex situ experimental observations reveal that the ρ-Cu15Si4 evolution is driven by interatomic diffusion, initially triggering the formation of binary-phase silicide islands (spheres) followed by the formation of hexagonal discs, stem growth, and lateral elongation in exactly opposite directions. It is further shown that electrochemically pregrown Cu crystals can facilitate the direct growth of ρ-Cu15Si4 in high yield with an enhanced substrate coverage.