Investigate on plasma catalytic reaction of 4-nitrobenzenethiol on Ag@SiO2Core-Shell substrate via Surface-enhanced Raman scattering

Abstract Surface-enhanced Raman scattering (SERS) is a promising technique to investigate the plasmon-driven catalytic reaction, in which the Raman signal originates from the electromagnetic (EM)enhancement mechanism and the chemical enhancement (CE) mechanism. Here, we designed and synthesized a novel SERS substrate based on SiO2 wrapped Ag nanoparticles (Ag@SiO2 core-shell nanoparticles substrate, Ag@SiO2 CSNS). Meanwhile, the SERS substrate based on Ag nanoparticles (Ag NS) also was prepared for comparison. Then, plasmon-driven catalytic reaction of 4-nitrobenzenethiol (4-NBT) to p,p′-dimercaptoazobenzene (DMAB) were systematically investigated on Ag and Ag@SiO2, respectively. The result revealed that, the Fermi level of Ag@SiO2 CSNS is lower than Ag NS, and the catalytic reaction greatly hindered by the Ag@SiO2 CSNS under the same excitation laser wavelength. With the same condition excitation laser, Raman signal enhancement effects are different when applying Ag NS and Ag@SiO2 CSNS, which could be attributed to that the inert SiO2 shell eliminates CE mechanism of the Raman signal. These results provide a simple strategy to figure out the mechanism of the catalytic reaction based on Surface-enhanced Raman scattering.