Silver nanoparticles decorated g-C₃N₄: An efficient SERS substrate for monitoring catalytic reduction and selective...

Graphitic carbon nitride supported Ag NPs(AgNPs@g-C₃N₄) were synthesized by an in-situ chemical reduction using a green reducing agent, tannic acid. They were characterized by UV-Vis, FTIR, XPS, XRD, FESEM, EDAX and HRTEM. They were very much SERS sensitive, and capable of detecting methylene blue and 4-aminothiophenol at 1 × 10^-12 M and 1 × 10^-10 M, respectively with the corresponding SERS enhancement factor of 1.4 × 10⁸ and 4.7 × 10⁷. Apart from its high SERS sensitivity, it exhibited high catalytic activity for the reduction of MB with NaBH₄. So, their SERS activity and catalytic activity were combined successfully to monitor catalytic reduction of MB by SERS technique. Further, the SERS activity towards MB was also employed for the detection/quantification of free Hg²⁺ ions in aqueous solution. The SERS intensity of MB drastically decreased in the presence of Hg²⁺ ions, and hence it provides novel route to detect and quantify the latter. Presence of Ca²⁺, Mg²⁺, Cu²⁺ and Cd²⁺ions showed zero interference for it. So, this study proves that Ag NPs@g-C₃N₄ as a unique substrate for multiple SERS applications.