Lattice mismatch-directed island growth for synthesizing rough-surfaced Ag-Cu heterostructured triangular nanoframes

Controllable synthesis of rough-surfaced metal nanostructures remains a critical challenge in surface materials science, as surface roughness directly determines the plasmonic, catalytic and sensing properties of nanomaterials. Herein, we report a facile lattice mismatch-directed island growth strategy for fabricating roughened Ag-Cu heterostructured triangular nanoframes with naturally roughened surfaces, using Cu nanoplates as dual-functional sacrificial templates. The intrinsic lattice mismatch between face-centered cubic Ag and Cu drives the preferential island-like nucleation of Ag atoms on the high-energy edges of Cu nanoplates, avoiding the formation of a continuous epitaxial layer. This unique growth mode generates nanoframes with abundant surface defects and dense plasmonic hot spots, while the residual Cu induces spontaneous interfacial electron transfer to form an electron-rich Ag surface. The as-prepared nanoframes exhibit 13.5-fold higher SERS activity than smooth monometallic Ag nanoplates, and show excellent performance in both aqueous dispersion and solid substrate configurations. This work provides a general and scalable approach for regulating the surface microstructure of template-derived nanostructures through lattice mismatch engineering.