Spontaneous synthesis of Ag nanoparticles decorated ZnAl layered double hydroxides for synergistically improved SERS activity

Surface enhanced Raman spectroscopy (SERS) is a rapid and ultrasensitive analytical technique. For practical applications, it is highly desirable to explore metal/semiconductor hybrid substrates, which utilize the synergistic enhancement effects of plasmons and charge transfer (CT). Herein, we successfully fabricated Ag nanoparticles decorated ZnAl LDHs nanosheets (Ag-ZnAl) by a facile one-pot solvothermal growth method and investigated the SERS performance. When 4-nitrobenzenethiol (4-NBT) was used as the probe molecule, the detection limit reaches as low as 1 x 10(-)(10) M and the enhancement factor is 1.7 x 10(5). A systematic experimental study revealed that the unique structure of LDH facilitates formation of densely distributed Ag NPs with good dispersibility, providing abundant hot spots for electromagnetic enhancement. Moreover, Ag-ZnAl hybrid has a higher concentration of oxygen vacancies, which can promote photo-induced CT for chemical enhancement. Furthermore, first principles calculations demonstrated that Ag-ZnAl hybrid has improved adsorption ability of 4-NBT through the formation of Ag-S and N-O-H bonds, which can facilitate charge transfer process and increase Raman intensity of 4-NBT. This work provides an effective strategy to design easy-to-fabricated metal/semiconductor hybrids as SERS sensing platform.

Automated summary

This study successfully fabricated Ag nanoparticles decorated ZnAl LDHs nanosheets and investigated their SERS performance. Experimental results demonstrated the influence of LDH structure and oxygen vacancies concentration of Ag-ZnAl hybrid on SERS performance.