A ternary ZnO/ZnS/MoS2 composite as a reusable SERS substrate derived from the polyoxomolybdate/ZIF-8 host–guest framework

A ternary nanocomposite containing ZnO, ZnS and MoS2 (ZnMoNCs) has been firstly synthesized by Keggin-type polyoxomolybdate and ZIF-8 as starting materials to provide Mo and Zn sources simultaneously. As compared to the mono- or bi-component complex, ZnMoNCs present more sensitive and stable surface-enhanced Raman scattering (SERS) activity. When rhodamine 6G is used as a probing molecule, the detection limit of 10−9 mol L−1 can be achieved on the ZnMoNC substrate with the enhancement factor (EF) of 1.4 × 108, which is the highest sensitivity among the known semiconductor SERS substrates. The increased adsorption sites and the synergistically improved charge transfer are conducive to the large enhancement of the SERS activity. It was also proved that the ZnMoNC substrate possesses high stability and self-cleaning properties, and can be reused in SERS detection without losing its activity even after 5 cycles. This work paves a new way to the design of new semiconductor SERS substrates by the utility of a multicomponent complex.