  To develop highly sensitive, stable and repeatable surface-enhanced Raman
scattering (SERS) substrates is crucial for analytical detection, which is a
challenge for traditional metallic structures. Herein, by taking advantage of
the high surface activity of 1T' transition metal telluride, we have fabricated
high-density gold nanoparticles (AuNPs) that are spontaneously in-situ prepared
on the 1T' MoTe2 atomic layers via a facile method, forming a plasmonic-2D
material hybrid SERS substrate. This AuNP formation is unique to the 1T' phase,
which is repressed in 2H MoTe2 with less surface activity. The hybrid structure
generates coupling effects of electromagnetic and chemical enhancements, as
well as excellent molecule adsorption, leading to the ultrasensitive (4*10^-17
M) and reproducible detection. Additionally, the immense fluorescence and
photobleaching phenomena are mostly avoided. Flexible SERS tapes have been
demonstrated in practical applications. Our approach facilitates the
ultrasensitive SERS detection by a facile method, as well as the better
mechanistic understanding of SERS beyond plasmonic effects.
