Site-Specific Growth of Ag Islands on Concave Au Nanocubes for SERS and LSPR-Based Applications

Currently, hybrid noble metal nanostructures have garnered significant interest due to their exceptional properties and diverse applications in fields such as catalysis, energy conversion, plasmonic sensing, and surface-enhanced Raman scattering (SERS). In this work, we report the highly site-specific growth of a single Ag island on both the concave face and the sharp tip of concave Au nanocube (c-AuNC) seeds, resulting in different c-AuNC-Ag Janus heterostructures. This site specificity was achieved by combining the surface curvature effect of the c-AuNCs with strong ligand-mediated interfacial energy control. Further integration of interfacial energy and growth kinetic control led to the formation of c-AuNC-(Ag)_n core–satellite structures with varying numbers of Ag satellites. Benefiting from the continuous tunability of the interfacial energy and growth kinetics, the structural evolution of the c-AuNC-Ag hybrid structures continuously occurred, enabling precise control of the Au–Ag bimetallic structures. Notably, the resulting c-AuNC-Ag structures showed tunable intense localized surface plasmon resonance (LSPR) absorptions within the 400–1000 nm wavelength along with strong SERS signals. The broad spectral absorption and strong SERS made the c-AuNC-Ag structures promising candidates for SERS and LSPR-based applications, including sensing, imaging, light energy harvesting, and conversion. Moreover, the effective synthetic control demonstrated in this work could facilitate the development of advanced hybrid metal nanomaterials with valuable properties, further broadening their application potential across various fields.