Silver nanoparticles decorated g-C3N4: An efficient SERS substrate for monitoring catalytic reduction and selective Hg2+ ions detection

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 x 10(-12) M and 1 x 10(-10) M, respectively with the corresponding SERS enhancement factor of 1.4 x 10(8) and 4.7 x 10(7). 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 Cd(2+)ions showed zero interference for it. So, this study proves that Ag NPs@g-C3N4 as a unique substrate for multiple SERS applications. (C) 2020 Elsevier B.V. All rights reserved.