AgNPs/CuNPs/Bragg-PSi substrate subjected to thermal annealing in high-sensitivity detection on crystal violets and diphenyl phthalate.

This study has successfully prepared three kinds of surface enhanced raman scattering (SERS) substrates, namely AgNP/CuNPs/Bragg-PSi (porous silicon, PSi), AgNPs/CuNPs/PSi and AuNPs/CuNPs/Bragg-PSi by use of an anode electrochemical etching method and a dip plating method. Results show that: the AgNPs/CuNPs/Bragg-PSi substrate has optimal SERS performance and is capable of detecting the Raman spectrum ( = 0.9315) of a 10 M-10 M crystal violet (CV) solution. By virtue of optimizing the concentration of copper nitrate for soaking the AgNPs/CuNPs/Bragg-PSi substrate and the annealing temperature for the AgNPs/CuNPs/Bragg-PSi substrate, this study has explored the influence of different preparation conditions on the performances of the substrate. Results show that: the optimal soaking concentration of the copper nitrate solution is 0.75 M, and the AgNPs/CuNPs/Bragg-PSi substrate annealed at 180 °C shows a more uniform microscopic structure and a stronger surface-enhanced effect. Finally, the annealed AgNPs/CuNPs/Bragg-PSi substrate is capable of realizing the high-sensitivity detection ( = 0.9898) on diphenyl phthalate within a concentration range of 10 M to 10 M. The AgNPs/CuNPs/Bragg-PSi substrate has the advantages of easiness and convenience in preparation, low cost, high sensitivity and the like, thus providing a broad prospect for application of SERS technology in the fields of chemical analysis and biological analysis and laying a foundation for developing more sensitive and reliable detection methods.