Synthesis and characterization of silver–polypyrrole film composite

doi:10.1016/j.apsusc.2009.08.060

Applied Surface Science

Volume 256, Issue 3, 15 November 2009, Pages 787-791

https://doi.org/10.1016/j.apsusc.2009.08.060 Get rights and content

Abstract

In this work, we report the chemical polymerization of pyrrole to obtain thin film of polypyrrole (PPy) hydrochloride deposited onto the electrode of the quartz crystal microbalance (QCM). The film in the base form was exposed to a solution of AgNO₃. Electroless reduction for silver ions by the PPy film took place and silver particles were adsorbed onto the film surface. The silver particles content at the PPy films were analyzed by QCM and the results showed that the concentrations of silver uptakes increase as the original AgNO₃ solution increases. The morphology of the surface of the PPy film and the silver–PPy film composite were studied by the scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDX). They showed that the obtained silver particles have spherical, cubic and tetrahedral structures. X-ray diffraction (XRD) and Fourier transformed infra-red spectroscopy (FTIR) were used to characterize the structure of the powder composite. This work reveals the capability of PPy film coating on QCM in sensing and removing silver from several environmental samples.

Introduction

The interest in the development of inorganic/organic composite has grown rapidly due to the wide range of high potential application of these materials. Among the organic part is conducting polymers, such as polyaniline or polypyrrole (PPy). Conducting polymers have redox properties and have been shown to be excellent hosts for trapping noble metal such as silver and gold [1], [2], [3], [4], [5]. The metal particles have attracted much attention in recent years due to their interesting properties and potential applications in technological fields [6]. Also, the metallization of conjugated polymers, in particular, have aroused considerable interest due to their potential applications in corrosion protection, microelectronic packaging and catalysis [7], [8], [9], [10].

Polypyrrole has been a focus of many studies because of its electrical conductivity and stability in comparison to the other conducting polymers [11]. It is a promising material for various electronic applications such as light emitting diode [12], organic FET [13], EMI shielding [14] and the secondary battery [15].

It is well known that PPy can be prepared by either electrochemical [16], [17], [18] or chemical method [19], [20], [21]. The electrochemical technique requires that the film be grown on a substrate that is itself conducting. In addition, the deposition of these films having uniform thickness on a topographically complex surface is extremely difficult. We previously described the deposition of smooth, adherent films of PPy using a chemical technique from an aqueous solution that contained FeCl₃ or K₂S₂O₈ as an oxidizing agent [22], [23]. These films were monitored by using quartz crystal microbalance (QCM). It has been shown that the films were able to be formed on conducting and insulating substrates. The variety of surfaces suggests that the formation of the PPy films is quite a general phenomenon, providing another degree of flexibility for the use of such polymer.

There are many silver–PPy composites that have been synthesized. Chen et al. have reported silver–PPy coaxial nanocables [24]. Pintér et al. have synthesized silver–PPy nanocomposites in the presence of different dopants [25]. The composite was also synthesized by Zhao and co-workers [3] based on mercaptocarboxylic acid capped silver nanoparticles colloid. silver–PPy nanofiber composites in dilute mixed cetyltrimethylammonium bromide/sodium dodecyl sulfate aqueous solution have also been synthesized [26].

In this paper, we will exploit PPy films coating on the electrode of QCM to uptake silver ions from aqueous solution. This could be applied to sensor silver ions in several wastewater samples obtained from industries that use large silver-containing compounds. Also, we look forward to synthesize the silver–PPy film composite that may find applications in catalysis or antimicrobial investigations. The amount of silver entrapped onto the films will be determined by using QCM. The morphology and structure of the composite will be examined using scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD) and Fourier transformed infra-red spectroscopy (FTIR).

Section snippets

Chemicals

The pyrrole was obtained from Aldrich Chemicals and was purified by passing through a column of alumina neutral. FeCl₃ and AgNO₃ were from BDH chemicals and used as received without any further purification.

Preparation of silver–PPy composite and QCM measurements

The PPy film was prepared from the oxidation of 0.0186 mol L⁻¹ solution of pyrrole dissolved in 50 ml of 0.2 mol L⁻¹ HCl and 0.0454 mol L⁻¹ FeCl₃ dissolved in 50 ml of 0.2 mol L⁻¹ HCl. In this case, the molar ratio of FeCl₃ to pyrrole would be 2.44. These solutions were then added to polypropylene

PPy film coating on the QCM for silver uptakes from solutions

The ability of PPy to sensor and uptake silver ions from aqueous AgNO₃ solutions were examined by QCM. Initially, the PPy film was grown onto the electrode of QCM from a solution. The mass per unit area of PPy film, m′ (g/cm²), was determined from the change in its resonance frequency. The relation between the frequency change Δf (Hz) and m′ is well established from the work of Sauerbrey [27] and is given by: $Δ f = - (2 f_{o}^{2} / \sqrt{ρ_{Q} μ_{Q}}) m^{'}$ where, f_o (Hz) is the natural frequency of the quartz crystal

Conclusions

The results of SEM, EDX, XRD and FTIR measurements indicate that the silver–PPy composite is successfully prepared. Also, based on these results, it can be concluded that the PPy coated electrode of QCM can be used efficiently to sensor silver ions in aqueous solution. This could be applied to several wastewater samples obtained from industries that use large amounts of silver-containing compounds. The resulted film composite can be used as a catalyst, antimicrobial substrate or biofilm. Also

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Synthesis and characterization of silver–polypyrrole film composite

Abstract

Introduction

Section snippets

Chemicals

Preparation of silver–PPy composite and QCM measurements

PPy film coating on the QCM for silver uptakes from solutions

Conclusions

Polymers

Synth. Met.

Mater. Lett.

Polymers

Synth. Met.

Appl. Catal. B: Environ.

Electrochim. Acta

Sens. Actuators B: Chem.

Synth. Met.

Electrochim. Acta

Synth. Met.

Synth. Met.

Synth. Met.

Mater. Lett.

Mater. Lett.

Mater. Chem. Phys.

Eur. Polym. J.

Polymers

J. Mater. Chem.