Site-Specific Growth\nof Ag Islands on Concave Au Nanocubes\nfor SERS and LSPR-Based Applications

Currently, hybrid noble metal nanostructures have garnered\nsignificant\ninterest due to their exceptional properties and diverse applications\nin fields such as catalysis, energy conversion, plasmonic sensing,\nand surface-enhanced Raman scattering (SERS). In this work, we report\nthe highly site-specific growth of a single Ag island on both the\nconcave face and the sharp tip of concave Au nanocube (c-AuNC) seeds,\nresulting in different c-AuNC-Ag Janus heterostructures. This site\nspecificity was achieved by combining the surface curvature effect\nof the c-AuNCs with strong ligand-mediated interfacial energy control.\nFurther integration of interfacial energy and growth kinetic control\nled to the formation of c-AuNC-(Ag)<sub><i>n</i></sub> core–satellite\nstructures with varying numbers of Ag satellites. Benefiting from\nthe continuous tunability of the interfacial energy and growth kinetics,\nthe structural evolution of the c-AuNC-Ag hybrid structures continuously\noccurred, enabling precise control of the Au–Ag bimetallic\nstructures. Notably, the resulting c-AuNC-Ag structures showed tunable\nintense localized surface plasmon resonance (LSPR) absorptions within\nthe 400–1000 nm wavelength along with strong SERS signals.\nThe broad spectral absorption and strong SERS made the c-AuNC-Ag structures\npromising candidates for SERS and LSPR-based applications, including\nsensing, imaging, light energy harvesting, and conversion. Moreover,\nthe effective synthetic control demonstrated in this work could facilitate\nthe development of advanced hybrid metal nanomaterials with valuable\nproperties, further broadening their application potential across\nvarious fields.