Surface-enhanced
Raman spectroscopy (SERS) is a promising ultrasensitive
analysis technology due to outstanding molecular fingerprint identification.
However, the measured molecules generally need to be adsorbed on a
SERS substrate, which makes it difficult to detect weakly adsorbed
molecules, for example, the volatile organic compound (VOC) molecules.
Herein, we developed a kind of a SERS detection method for weak adsorption
molecules with Au@ZIF-8 core–shell nanoparticles (NPs). The
well-uniformed single- and multicore–shell NPs can be synthesized
controllably, and the shell thickness of the ZIF-8 was able to be
precisely controlled (from 3 to 50 nm) to adjust the distance and
electromagnetic fields between metal nanoparticles. After analyzing
the chemical and physical characterization, Au@ZIF-8 core–shell
NPs were employed to detect VOC gas by SERS. In contrast with multicore
or thicker-shell nanoparticles, Au@ZIF-8 with a shell thickness of
3 nm could efficiently probe various VOC gas molecules, such as toluene,
ethylbenzene, and chlorobenzene. Besides, we were capable of observing
the process of toluene gas adsorption and desorption using real-time
SERS technology. As observed from the experimental results, this core–shell
nanostructure has a promising prospect in diverse gas detection and
is expected to be applied to the specific identification of intermediates
in catalytic reactions.