Elsevier

Synthetic Metals

Volume 159, Issue 13, July 2009, Pages 1332-1335
Synthetic Metals

Silver–polypyrrole composites: Facile preparation and application in surface-enhanced Raman spectroscopy

https://doi.org/10.1016/j.synthmet.2009.03.002Get rights and content

Abstract

A facile method to prepare silver–polypyrrole composite (Ag–PPy) by a modified silver mirror reaction is reported. PPy films pretreated by Al(NO3)3 solution were immersed into the silver ammonia with glucose. Silver ammonia ions were reduced to two-dimensional staggered silver nanosheets which immobilized on the surface of polypyrrole. The silver nanosheets with different morphologies and sizes can serve as active-substrates for surface-enhanced Raman spectroscopy (SERS). Using 4-mercaptopyridine (4-Mpy) as probe molecules, the as-prepared composites exhibited excellent surface-enhanced Raman scattering.

Introduction

Incorporation metal nanoparticles into conducting polymer is of interest due to the strong electronic interaction between the metal and conducting polymer. Such metal-conducting polymer composites have attracted growing attention because of their potential applications in biotechnology, electro-catalysis, sensors, microelectronic devices [1], [2], [3], [4], and as substrates for surface-enhanced Raman spectroscopy (SERS) [5].

Surface-enhanced Raman spectroscopy is a powerful surface diagnostic technique because of its extremely high surface sensitivity [6], [7], [8]. Among the SERS-active metals, Ag nanostructure had been widely studied [9], [10] and the relevant results exhibits the shapes of Ag nanostructures influenced the SERS [11], [12], [13], [14]. However, most of the methods are too laborious and expensive to fabricate in large quantities.

Herein, we describe a facile way to fabricate novel silver–polypyrrole (Ag–PPy) composite as SERS-active substrate. By the modified silver mirror reaction, the small size, large surface area, and plate-like structure of the silver nanosheets were deposited on the surface of PPy. The obtained Ag–PPy substrate is very stable, inexpensive, and exhibits excellent SERS enhancement ability.

Section snippets

Materials

Poly(4-styrene sulfonic acid) (PSSA) (18 wt.% aqueous solution) and 4-mercaptopyridine (4-Mpy) were purchased from Aldrich. Pyrrole (Chinese Army Medical Institute) was distilled under reduced pressure before use. Silver nitrate (99.8%) was purchased from Beijing Chemical Plant (Beijing, China). Ammonia (25%) was bought from Tianjing 3rd Chemical Reagent Plant (Tianjing, China). Glucose monohydrate (99%) was purchased from Beijing Yili Fine Chemical Corporation (Beijing, China). Aluminum nitrate

Characterization of silver–PPy composites

The silver mirror reaction led to the coating of large-scale plate-like silver nanostructures on the surfaces of PPy. Fig. 1A shows the surface of PPy film doped by PSSA is very smooth. After the silver mirror reaction for 1 min, the image of the silver nanostructure is shown in Fig. 1B.

Fig. 1C–F shows the morphologies of the silver nanostructures grown for 5 min, 15 min, 30 min, and 60 min, respectively, which implied that the silver nanosheets are evenly deposited and coved completely the surface

Conclusions

In the present work, we have provided a simple method of fabrication of silver–PPy composites by a modified silver mirror reaction. The as-prepared silver–PPy composites exhibit excellent enhancement ability as SERS substrate, which are expected to have wide applications in sensor and other related field.

Acknowledgements

This work was supported by Education Department of Zhejiang Province (Y200804576) and K.C. Wong Magna Fund in Ningbo University. In addition, we acknowledge Prof. G.Q. Shi for helpful discussion (Tsinghua University, People's Republic of China).

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