A low-cost 3D core-shell nanocomposite as ultrasensitive and stable surface enhanced Raman spectroscopy substrate

It is a great challenge to assemble low-cost and recyclable surface enhanced Raman scattering (SERS) substrates for sensitive detection towards target analytes. In this work, a 3D core-shell Cu2O@SiO2@zinc 2-methylimidazolate metal-organic frameworks@Ag nanocomposite (Cu2O@SiO2@ZIF-8@Ag) was facilely fabricated only with 0.5 wt.% Ag. The successful construction of the novel Cu2O-based SERS platform with special structure was confirmed by scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, and Xray photoelectron spectroscopy. It showed that the nanocomposite can offer high-dispersion and small size Ag NPs implanted on the Cu2O@SiO2@ZIF-8, thus providing high-density hotspots. Importantly, the nanocomposite exhibited a highly sensitive and stable SERS response toward crystal violet (CV, a dose-related carcinogen) molecules. Especially, it can be detected as low as 1 x 10(-19) M. The considerable SERS enhancement over the nanocomposite was owed to the special Ag and the powerful enrichment effect of the ZIF-8 shell sustained by the Cu2O@SiO2 core. Moreover, with the nanocomposite as the SERS substrate towards CV detection, the high SERS performance was still kept even after 15 cycles and even after placed in the air for 40 days. Additionally, a little silver and good selectivity were both significant for reliable quantitative detection in practical application.

Automated summary

A novel Cu2O-based SERS platform with special structure was successfully constructed, offering high sensitivity and stable response towards crystal violet molecules. The nanocomposite exhibited considerable SERS enhancement for CV detection, maintaining high performance even after multiple cycles and long-term exposure.