Significant Enhancement of Dynamic SERS Signals Achieved Using Alloy Superatoms as Substrates.

Due to the strong charge transferability brought by delocalized superatomic molecular orbitals, coinage metal (CM) superatoms exhibit significant potential in surface-enhanced Raman scattering (SERS). However, the scarcity of metal elements in the coinage family restricts further improvement. To address this, we propose the idea of using different types of CMs to form alloyed superatoms. First-principles calculations reveal that substitution sites during alloying significantly influence the structural and optical properties. High-symmetry alloy superatoms exhibit enhanced stability and SERS intensities 10-10 times higher than other low-symmetry structures. More importantly, compared with that of the pure metal shell substrates, their absolute Raman intensity increases by an order of magnitude, reaching up to 10. This enhancement arises from the charge transfer at the alloy superatom-pyridine interface, which increases the system's polarizability derivative. This study provides a preliminary yet promising strategy for designing metal substrates with both high signal enhancement capability and excellent structural stability.