Use of Single-Layer g-C3N4/Ag Hybrids for Surface-Enhanced Raman Scattering (SERS).

Wenjing Zhang,Jizhou Jiang,Jing Zou,Andrew Thye Shen Wee

doi:10.1038/srep34599

Abstract

Surface-enhanced Raman scattering (SERS) substrates with high activity and stability are desirable for SERS sensing. Here, we report a new single atomic layer graphitic-C3N4 (S-g-C3N4) and Ag nanoparticles (NPs) hybrid as high-performance SERS substrates. The SERS mechanism of the highly stable S-g-C3N4/Ag substrates was systematically investigated by a combination of experiments and theoretical calculations. From the results of XPS and Raman spectroscopies, it was found that there was a strong interaction between S-g-C3N4 and Ag NPs, which facilitates the uniform distribution of Ag NPs over the edges and surfaces of S-g-C3N4 nanosheets, and induces a charge transfer from S-g-C3N4 to the oxidizing agent through the silver surface, ultimately protecting Ag NPs from oxidation. Based on the theoretical calculations, we found that the net surface charge of the Ag atoms on the S-g-C3N4/Ag substrates was positive and the Ag NPs presented high dispersibility, suggesting that the Ag atoms on the S-g-C3N4/Ag substrates were not likely to be oxidized, thereby ensuring the high stability of the S-g-C3N4/Ag substrate. An understanding of the stability mechanism in this system can be helpful for developing other effective SERS substrates with long-term stability.

Highlights

Surface-enhanced Raman scattering (SERS) is a powerful spectroscopy technique for molecular detection and characterization that relies on the enhanced Raman scattering of molecules that are adsorbed on, or near, SERS-active surfaces, such as nanostructured gold or silver[1,2]
The bulk g-C3N4 was prepared by polymerization of melamine under an air atmosphere[1]
These results indicate that the micrometer-size sheet-like g-C3N4 had been successfully prepared

Summary

Introduction

Surface-enhanced Raman scattering (SERS) is a powerful spectroscopy technique for molecular detection and characterization that relies on the enhanced Raman scattering of molecules that are adsorbed on, or near, SERS-active surfaces, such as nanostructured gold or silver[1,2]. Wolosiuk et al.[21] demonstrated a simple substrate platform based on mesoporous oxide (TiO2, SiO2, and ZrO2) thin films containing Ag NPs for SERS chemical analysis, and the SERS activity variation of the nanocomposite substrates was within 10% of the original signal after storage of up to 42 months. These techniques can increase the stability of SERS substrates, the core-shell structure usually involve complex preparation processes and the thickness of metal shell is difficult to control. This work can provide a useful resource for further optimization of SERS substrates with high stability

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