A spontaneously formed plasmonic-MoTe₂ hybrid platform for ultrasensitive Raman enhancement

Development of highly sensitive, stable, and repeatable surface-enhanced Raman scattering (SERS) substrates is crucial for analytical detection, which is a challenge for traditional metallic structures. Here, by exploiting the high surface activity of the 1T′ transition metal telluride, we fabricate high-density gold nanoparticles (AuNPs) that are prepared spontaneously in situ on the 1T′ MoTe₂ atomic layers, forming a plasmonic-2D material hybrid SERS substrate. This AuNP formation is unique to the 1T′ phase, which is repressed in 2H MoTe₂ with lower surface activity. The hybrid structure generates coupling effects of electromagnetic and chemical enhancements, as well as excellent molecule adsorption, leading to ultrasensitive (4 × 10⁻¹⁷ M) and reproducible detection. Flexible SERS tapes are demonstrated in practical applications. Our approach facilitates ultrasensitive SERS detection by a facile method, as well as an enhanced mechanistic understanding of SERS beyond plasmonic effects.