CONDUCTING POLYMER COMPOSITES CONTAINING IRON OXIDE/HYDROXIDE AND THEIR PREPARATION USING FERRATE SALTS

Abstract

The primary subject of the invention is an iron oxide/hydroxide-containing conducting polymer composite, which comprises a) a conducting polymer, and b) an iron oxide/hydroxide compound incorporated in the conducting polymer wherein the composite contains iron oxide/hydroxide compound other than magnetite, and the conducting polymer is different from polyaniline (PANI). The further subject of the invention is the process for the electrochemical production of the above-mentioned conducting polymer composite by one of the following processes: Process I, which comprises the following steps: a) providing a conducting polymer layer; b) electrochemical reduction of the conducting polymer layer; c) contacting the reduced conducting polymer layer with an aqueous solution of ferrate ions; d) optionally repeating steps b) and c); e) optionally separating and drying the obtained composite; or Process II, which comprises the following steps: a) providing a conducting polymer layer; b) contacting the conducting polymer layer with an aqueous solution of ferrate ions; c) electrochemical oxidation of the conducting polymer layer in an aqueous solution of ferrate ions; d) electrochemical reduction of the oxidized conducting polymer layer in an aqueous solution of ferrate ions; e) optionally repeating steps c) and d); e) optionally separating and drying the obtained composite.

Claims

1. A process for the electrochemical production of an iron oxide/hydroxide-containing conducting polymer composite by one of the following processes: Process I, which comprises the following steps: a) providing a conducting polymer layer, optionally performing partial irreversible electrochemical oxidation (overoxidation) on the conducting polymer layer; b) electrochemical reduction of the conducting polymer layer, optionally in a solution containing ferrate ions; c) contacting the reduced conducting polymer layer with an aqueous solution of ferrate ions; d) optionally repeating steps b) and c); e) optionally separating the composite from the electrode used in the electrochemical reactions, and, if desired, drying the composite; or Process II, which comprises the following steps: a) providing a conducting polymer layer, optionally electrochemically reducing the conducting polymer layer; b) contacting the conducting polymer layer with an aqueous solution of ferrate ions; c) electrochemical oxidation of the conducting polymer layer in an aqueous solution of ferrate ions; d) electrochemical reduction of the oxidized conducting polymer layer in an aqueous solution of ferrate ions; e) optionally repeating steps c) and d); f) optionally separating the composite from the electrode used in the electrochemical reactions, and, if desired, drying the composite.

2. The process according to claim 1, wherein in steps I a) and II a), the conducting polymer layer is produced in an electrochemical way, in which the conducting polymer layer is deposited on a substrate by galvanostatic or potentiodynamic way.

3. The process according to claim 2, wherein the substrate is selected from: gold, platinum, graphite, glassy carbon, conducting carbon layers and carbon fibers; preferably gold.

4. The process according to claim 1, wherein steps I b) and I c) or steps II c) and II d) are repeated 5 to 20 times, preferably 8 to 12 times in step I d), or in step II e).

5. The process according to claim 1, wherein the reduction according to step I b) is performed in a solution that is containing ferrate ions, and the contacting according to step I c) is performed in a way that the conducting polymer layer is allowed to stand in the ferrate solution of step I b), and optionally additional ferrate salt, preferably Na or K salt, is added to the solution.

6. The process according to claim 1, wherein in step II e), steps c) and d) are repeated by cyclic voltammetry (i.e., potentiodynamic cyclization).

7. An iron oxide/hydroxide-containing conducting polymer composite, which is obtainable by the processes according to claim 1.

8. The iron oxide/hydroxide-containing conducting polymer composite according to claim 7, wherein the conducting polymer is reinforced with a polymer deposited on it, preferably the deposited polymer is poly(bisphenol A) [PBPA].

9. An iron oxide/hydroxide-containing conducting polymer composite, which comprises a) a conducting polymer, and b) an iron oxide/hydroxide compound incorporated in the conducting polymer, wherein the iron oxide/hydroxide compound is other than magnetite (Fe.sub.3O.sub.4), and wherein the conducting polymer is different from polyaniline (PANI), and wherein the conducting polymer is reinforced with a polymer deposited on it.

10. The iron oxide/hydroxide-containing conducting polymer composite according to claim 9, wherein the polymer deposited on conducting polymer is electrodeposited poly(bisphenol A) [PBPA].

11. The iron oxide/hydroxide-containing conducting polymer composite according to claim 9, wherein the conducting polymer is selected from poly(3,4-ethylenedioxythiophene) i.e., PEDOT and poly(orthophenylenediamine) i.e., PoPD, preferably PEDOT.

12. The iron oxide/hydroxide-containing conducting polymer composite according to claim 9, wherein the iron oxide/hydroxide compound is selected from: Fe.sub.2O.sub.3, Fe(OH).sub.2, Fe(OH).sub.3, and FeO(OH).

13. The iron oxide/hydroxide-containing conducting polymer composite according to claim 9, wherein the amount of iron oxide/hydroxide compound other than magnetite is at least 1 to 25 wt %, preferably it is 2 to 10 wt % in the composite, calculated from the total mass of the iron oxide/hydroxide compounds.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0040] FIG. 1 a) shows cyclic voltammograms (curves are recorded during the third cycle, E=(?0.3)-(+0.6) V vs. SSCE, v=100 mV/s); FIG. 1 b) shows the logarithm of the (frequency-dependent) capacitance values (Y/?) calculated from the impedance spectrum (E=0.1 V vs. SSCE) as a function of the logarithm of the frequency. Measurements were carried out in 0.1 M Na.sub.2SO.sub.4 electrolyte solution, (1) indicates a PEDOT film that was deposited on a gold (A=0.196 cm.sup.2) substrate, and prepared according to Example 3, and (2) indicates a PEDOT|iron oxide/hydroxide layer.

[0041] FIG. 2 a) and b) shows SEM images of a PEDOT|iron oxide/hydroxide composite layer deposited on a gold substrate according to Example 1 (Table 1 #1) with a) secondary electrons b) backscattered electrons. The scales at the bottom of the images correspond to 50 ?m. FIG. 2 c) shows an EDX spectrum that demonstrates the atomic composition of the sample, and the peaks corresponding to iron are indicated as well.

[0042] FIG. 3 shows the increased resistance of the PBPA-reinforced PEDOT layer to overoxidation compared to the bisphenol A-untreated PEDOT film. PEDOT (FIG. 3 a)) and PEDOT/PBPA (FIG. 3 b)) samples were deposited on a gold substrate according to Example 7. Photographs of the layers after strong overoxidation show a good structure-reinforcing effect of PBPA.

EXAMPLES

[0043] All electrochemical measurements were performed at room temperature (22.0?0.5) ? C. Solutions were saturated with oxygen free argon gas (Linde 5.0) before use, and the inert gas atmosphere was maintained during the experiments. Electrochemical measurements were performed with a Zahner IM6 electrochemical workstation controlled by a Thales software. Scanning electron microscopic (SEM) images were taken with a Quanta? 3D FEG high-resolution dual-beam scanning electron microscope (SEM/FIB). Both secondary and scattered electrons were detected during scanning.

[0044] Investigation of the PEDOT Layer

[0045] The electrochemical investigation of the PEDOT layer was carried out in a three-electrode cell, which has a volume of 150 cm.sup.3, and the working electrode was a PEDOT layer, deposited on a gold disk (A=0.196 cm.sup.2), the reference electrode was a sodium chloride saturated calomel electrode (SSCE), and the counter electrode was a ring-shaped platinum plate. These electrodes were immersed in a 0.1 mol/dm.sup.3 H.sub.2SO.sub.4 solution. The potential window used in cyclic voltammetric studies was E=(?0.1)-(+0.8) V vs. SSCE, scan rates were v=100 and 50 mV/s. Electrochemical impedance spectroscopic (EIS) measurements were performed in the frequency range of 50 kHz to 96.1 mHz, the perturbation signal amplitude was 5 mV, and the electrode potential was E=(+0.4) V or (+0.2) V vs. SSCE.

[0046] I. Synthesis of PEDOT Layer-Containing Composites

Example 1

[0047] (1) The electrochemical deposition of PEDOT layer was carried out in a three-electrode cell, which has a volume of 150 cm.sup.3. The deposition was performed on a gold substrate (A=0.196 cm.sup.2) under galvanostatic conditions (j=0.2 mA/cm.sup.2, t=3600 s). The composition of the monomer-containing solution was: 0.01 M EDOT/0.1 M Na.sub.2SO.sub.4 (pH=6). The counter electrode was a ring-shaped platinum plate. A potassium chloride saturated calomel electrode (SCE) was used as a reference electrode. [0048] (2) The reduction of the deposited PEDOT layer was carried out in a 0.1 M Na.sub.2SO.sub.4 (pH=5) solution (E=?0.3 V, t=120 s). A sodium chloride saturated calomel electrode (SSCE) was used as a reference electrode. [0049] (3) The reduced PEDOT layer was immersed in a 0.05 M Na.sub.2FeO.sub.4/NaOH solution (t=30 s; pH=14-10*). [0050] (4) Steps (2) and (3) were repeated 10 times consecutively.

[0051] *: The pH is decreasing during the process.

[0052] The following examples were carried out basically as described in Example 1, therefore, only the main characteristics will be given of the processes.

Example 2

[0053] (1) Electrochemical deposition of PEDOT layer on gold substrate, under galvanostatic conditions (j=0.2 mA/cm.sup.2, t=3600 s) from 0.01 M EDOT/0.1 M Na.sub.2SO.sub.4 electrolyte (counter electrode: Pt, reference electrode: SCE). [0054] (2) The reduction of the deposited PEDOT layer in a 0.1 M Na.sub.2SO.sub.4 (pH=5) solution (E=?0.3-(+1.1) V vs. SSCE; v=50 mV/s, 3 cycles). In case of the applied positive potential limit, the polymer partly oxidizes irreversibly (overoxidation), therefore the structure becomes more porous, facilitating the entry of ions into the polymer film. [0055] (3) The reduction of the deposited PEDOT layer was carried out in a 0.1 M Na.sub.2SO.sub.4 (pH=5) solution [0056] (E=?0.3 V vs. SSCE; t=120 s). [0057] (4) The reduced PEDOT layer was immersed in a 0.05 M Na.sub.2FeO.sub.4/NaOH solution (pH=14-10*, t=30 s). [0058] (5) Steps (3) and (4) were repeated 10 times consecutively.

[0059] *: The pH is decreasing during the process.

Example 3

[0060] (1) Electrochemical deposition of PEDOT layer on gold substrate, under galvanostatic conditions (j=0.2 mA/cm.sup.2, t=3600 s) from 0.01 M EDOT/0.1 M Na.sub.2SO.sub.4 electrolyte (counter electrode: Pt, reference electrode: SCE). [0061] (2) The reduction of the deposited PEDOT layer in a 0.1 M Na.sub.2SO.sub.4 (pH=5) solution [0062] (E=?0.3 V vs. SSCE; t=300 s). [0063] (3) The reduced PEDOT layer was immersed in a 0.05 M Na.sub.2FeO.sub.4/NaOH solution (pH=14-10*,t=300 s).

[0064] *: The pH is decreasing during the process.

Example 4

[0065] (1) Electrochemical deposition of PEDOT layer on gold substrate, under galvanostatic conditions (j=0.2 mA/cm.sup.2, t=3600 s) from 0.01 M EDOT/0.1 M Na.sub.2SO.sub.4 electrolyte (counter electrode: Pt, reference electrode: SCE). [0066] (2) The reduction of the deposited PEDOT layer in a 0.05 M Na.sub.2FeO.sub.4/NaOH (pH=14*) solution [0067] (E=?0.56 V vs. SSCE; t=300 s).

[0068] Immersion of the reduced PEDOT layer in the solution of step (2) (t=300 s).

[0069] *: The pH is decreasing during the process.

Example 5

[0070] (1) Electrochemical deposition of PEDOT layer on gold substrate, under galvanostatic conditions (j=0.2 mA/cm.sup.2, t=1000 s) from 0.01 M EDOT/0.1 M Na.sub.2SO.sub.4 electrolyte (counter electrode: Pt, reference electrode: SCE). [0071] (2) The reduction of the deposited PEDOT layer in a 0.1 M Na.sub.2SO.sub.4 (pH=5) solution [0072] (E=?0.3 V vs. SSCE; t=120 s). [0073] (3) The reduced PEDOT layer was immersed in a 0.05 M Na.sub.2FeO.sub.4/NaOH solution (pH=14-10*, t=30 s). [0074] (4) Steps (2) and (3) were repeated 10 times consecutively.

[0075] *: The pH is decreasing during the process.

Example 6

[0076] (1) The electrochemical deposition of PEDOT layer was carried out in a three-electrode cell, which has a volume of 150 cm.sup.3. The deposition was performed on a gold substrate (A=0.196 cm.sup.2) under galvanostatic conditions (j=0.2 mA/cm.sup.2, t=3600 s). The composition of the monomer-containing solution was: 0.01 M EDOT/0.1 M Na.sub.2SO.sub.4 (pH=5). The counter electrode was a ring-shaped platinum plate. A potassium chloride saturated calomel electrode (SCE) was used as a reference electrode. [0077] (2) The reduction of the deposited PEDOT layer was carried out in a 0.1 M Na.sub.2SO.sub.4 (pH=5) solution (E=?0.3 V, t=120 s). A sodium chloride saturated calomel electrode (SSCE) was used as a reference electrode. [0078] (3) The reduced PEDOT layer was immersed in a 0.05 M Fe.sub.2FeO.sub.4/KOH solution (t=30 s; pH=14-10*). [0079] (4) Steps (2) and (3) were repeated 10 times consecutively.

[0080] *: The pH is decreasing during the process.

Example 7

[0081] (1) Electrochemical deposition of PEDOT film on gold substrate, under galvanostatic conditions (j=0.2 mA/cm.sup.2, t=3600 s) from 0.01 M EDOT/0.1 M Na.sub.2SO.sub.4 electrolyte (pH=5, counter electrode: Pt, reference electrode: SCE). [0082] (2) The reduction of the deposited PEDOT layer in a 0.1 M Na.sub.2SO.sub.4 (pH=5) solution [0083] (E=?0.3 V vs. SSCE; t=300 s). [0084] (3) The immersion of the reduced polymer layer into 0.05 M Na.sub.2FeO.sub.4/NaOH solution and its cyclic potentiodynamic polarization: 21 cycles (pH=14-10*, E=(?0.4)-(+0.3 V) vs. SCE; v=100 mV/s.)

[0085] *: The pH is decreasing during the process.

Example 8

[0086] (1) Electrochemical deposition of PEDOT layer on gold substrate, under galvanostatic conditions (j=0.2 mA/cm.sup.2, t=3600 s) from 0.01 M EDOT/0.1 M Na.sub.2SO.sub.4 electrolyte (counter electrode: Pt, reference electrode: SCE). [0087] (2) The immersion of PEDOT layer into 0.05 M K.sub.2FeO.sub.4/KOH solution, and its cyclic potentiodynamic polarization: 21 cycles (pH=14-10*, E=(?0.4)-(+0.3) V vs. SCE; v=100 mV/s.)

[0088] *: The pH is decreasing during the process.

[0089] Table 1 summarizes the parameters of the production of various PEDOT/Fe.sub.xO.sub.y composites and their iron content in atomic percent (atom %).

TABLE-US-00001 TABLE 1 Production parameters of PEDOT/iron oxide/hydroxide composites deposited on a gold substrate (t.sub.dep: deposition time of the PEDOT layer, Overox: occurrence of overoxidation of the PEDOT layer, t.sub.red: reduction time, E.sub.red: reduction potential compared to SSCE electrode, pH.sub.red: pH of the reduction medium, t.sub.imm.: immersion time, atom % (Fe): data obtained from EDX measurements). reduction + immersion number of atom % # t.sub.dep/s Overox t.sub.red./s E.sub.red./V pH.sub.red. medium t.sub.imm/s immersions (Fe) 1 3600 ? 120 ?0.3 5 0.05M FeO.sub.4.sup.2?/ 30 10 3.14 2 3600 + 120 ?0.3 5 NaOH 30 10 5.40 3 3600 ? 300 ?0.3 5 pH = 14-10 300 1 3.39 4 3600 ? 300 ?0.56 14 300 1 9.15 5 1000 ? 120 ?0.3 5 30 10 2.54 6 3600 ? 120 ?0.3 5 30 10 7.32 7 3600 ? 300 ?0.3 5 * 1 5.84 8 3600 ? ? ? ? * 1 10.21 * potentiodynamic: 21 cycles, E = (?0.4) ? (+0.3 V) vs. SCE; v = 100 mV/s

[0090] The content of FIG. 1 is discussed here in more detail: a) cyclic voltammograms (curves are recorded in the third cycle, E=(?0.3)-(+0.6) V vs. SSCE, v=100 mV/s) and b) logarithm of the (frequency-dependent) capacitance values (Y/?) calculated from the impedance spectrum (E=0.1 V vs. SSCE) as a function of the logarithm of the frequency (as a function of the logarithm of the frequency of the perturbing signal) of the PEDOT films (1) deposited on a gold substrate (A=0.196 cm.sup.2), prepared according to Example 3, and of the PEDOT/iron oxide/hydroxide layer (2) in 0.1 M Na.sub.2SO.sub.4 electrolyte. Investigating the electrochemical properties of the composite, it is seen that the iron-containing composite also preserved the capacitive property of the original film containing only the conducting polymer (FIG. 1 a)). The low-frequency capacity of the composite layer moderately increased, while there is a definite rise in capacity in the mid-range compared to the pure PEDOT layer without iron oxide/hydroxide (FIG. 1 b)). In practice, this growth in capacity means that the iron content of the polymer layer is electrochemically active, that is, the oxidation state can be tuned by changing the potential. Furthermore, the capacity of the modified polymer film is linear over a wider range, which is a highly advantageous property for its use as a supercapacitor.

[0091] The content of FIG. 2 is discussed here in more detail: From the PEDOT/iron oxide/hydroxide composite layer deposited on gold support prepared according to Example 1 (Table 1 #1) a) SEM images recorded with secondary electrons b) backscattered electrons and c) EDX spectra showing the atomic composition of the sample, in which peaks can be seen that correspond to iron. The scales at the bottom of the figures correspond to 50 ?m. Electron microscopic images demonstrated that the PEDOT|iron oxide/hydroxide composite films also show the cauliflower-like structures that are characteristic for PEDOT. In the backscattered electron images, the composite (darker details) can be well distinguished from the gold substrate (light details). Based on these, it can be observed that the layer is heavily cracked, not homogeneous, which is probably the effect of the steps used in the synthesis of the composite (overoxidation).

[0092] The presence of iron oxides in layers can also be detected by Mossbauer spectroscopy. The composition cannot be given due to the small size of the iron-containing crystals.

[0093] II. Production of a Conducting Polymer Layer Reinforced with PBPA Layer

Example 9

[0094] Preparation of PEDOT Film Reinforced with Poly(Bisphenol A) [PBPA]

[0095] Step 1: Deposition of Poly(3,4-Ethylenedioxythiophene) Layer

[0096] The electrochemical deposition of the PEDOT layer was carried out in a three-electrode cell, which has a volume of 150 cm.sup.3, in which the working electrode was a gold disk (A=0.196 cm.sup.2), the reference electrode was the potassium chloride saturated calomel electrode (SCE), and the counter electrode was a ring-shaped platinum disk. These electrodes were immersed in a 0.01 mol/dm.sup.3 EDOT/0.1 mol/dm.sup.3 Na.sub.2SO.sub.4 (pH=5) as-prepared solution. We applied j=0.2 mA/cm.sup.2 current density during the galvanostatic deposition. The deposition time was t=1800 s.

[0097] The prepared polymer layer was soaked in Milli-Q water for relaxation for one day (thus ensuring the removal of the oligomers).

[0098] Step 2: Deposition of Poly(Bisphenol A) [PBPA] Layer

[0099] The electrochemical deposition of the PBPA layer on the PEDOT layer was performed with a potentiodynamic method, in a 30 cm 3 three-electrode cell, in which the working electrode was the PEDOT layer, deposited on a gold plate (A=0.196 cm.sup.2), immersed in a 100 ppm BPA/0.5 mol/dm.sup.3 H.sub.2SO.sub.4 (pH=0.6) solution; reference electrode was a saturated sodium chloride filled calomel electrode (SSCE); and the counter electrode was a platinum wire. During potentiodynamic deposition, the potential window was E=?0.1-(+1.0) V vs. SSCE, scanning speed was v=100 mV/s, and the number of cycles was 10.

[0100] Step 3: Investigation of the PEDOT/PBPA Layer

[0101] The electrochemical deposition of the PEDOT layer was carried out in a three-electrode cell, which has a volume of 150 cm.sup.3, in which the working electrode was a gold disk (A=0.196 cm.sup.2), the reference electrode was potassium chloride saturated calomel electrode (SCE), the counter electrode was a ring-shaped platinum plate. These electrodes were immersed in a 0.1 mol/dm.sup.3 EDOT/0.1 mol/dm.sup.3 Na.sub.2SO.sub.4 (pH=1.3) as-prepared solution. The potential window during the cyclic voltammetric investigations was E=(?0.1)-(+0.8) V vs. SSCE, scanning speed was v=100, and 50 mV/s. Electrochemical impedance spectroscopic (EIS) measurements were performed in the frequency range of 50 kHz-96.1 mHz, the perturbation signal amplitude was 5 mV, and the electrode potential was E=0.4 V or 0.2 V vs. SSCE.

[0102] Step 4: Overoxidation of the PEDOT/PBPA Layer

[0103] The overoxidation of the PEDOT layer, prepared in step 2, was carried out in a three-electrode cell, its volume was 150 cm.sup.3, and the working electrode is a PBPA reinforced PEDOT layer deposited on a gold disk (A=0.196 cm.sup.2), the reference electrode was sodium chloride saturated calomel electrode (SSCE), the counter electrode was a ring-shaped platinum plate. These electrodes were immersed in a 0.1 mol/dm.sup.3 H.sub.2SO.sub.4 solution. During overoxidation, the potential window was E=0.4-1.5 V vs. SSCE, scanning speed was v=50 mV/s, and the number of cycles was 3.

[0104] Step 5: Investigation of the Overoxidized PEDOT Layer

[0105] The electrochemical investigation of the overoxidized PEDOT layer, prepared in step 4, was carried out in a three-electrode cell, its volume was 150 cm.sup.3, in which the working electrode is a PBPA-reinforced PEDOT layer deposited on a gold disk (A=0.196 cm.sup.2), the reference electrode was sodium chloride saturated calomel electrode (SSCE), and the counter electrode was a ring-shaped platinum plate. These electrodes were immersed in a 0.1 mol/dm.sup.3 H.sub.2SO.sub.4 solution. The potential window during the cyclic voltammetric investigations was E=(?0.1)-(+0.8) V vs. SSCE, scanning speed was v=100 and 50 mV/s. Electrochemical impedance spectroscopic (EIS) measurements were performed in the frequency range of 50 kHz-96.1 mHz, the perturbation signal amplitude was 5 mV, and the electrode potential was E=0.4 V or 0.2 V vs. SSCE.

[0106] The content of FIG. 3 discussed in more detail: Studies have shown that the PBPA-supported/reinforced PEDOT layer is more resistant to overoxidation than the pure PEDOT film. Unlike the PEDOT film (FIG. 3a), the PEDOT/PBPA layer (FIG. 3b) did not delaminate from the substrate caused by overoxidation.

Example 10

[0107] Deposition of the Bisphenol A Layer after the Ferrate Treatment [0108] (1) Electrochemical deposition of PEDOT layer on gold substrate, under galvanostatic conditions (j=0.2 mA/cm.sup.2, t=3600 s) from 0.01 M EDOT/0.1 M Na.sub.2SO.sub.4 electrolyte (pH=5, counter electrode: Pt, reference electrode: SCE). [0109] (2) The immersion of PEDOT layer into 0.05 M K.sub.2FeO.sub.4/KOH solution, and its potentiodynamic cyclization: 21 cycles, (pH=14-10*, E=?0.4-(+0.3) V vs. SCE; v=100 mV/s.)

[0110] *: The pH is decreasing during the process. [0111] (3) Deposition of poly(bisphenol A) layer from 100 ppm BPA/0.1 M Na.sub.2SO.sub.4 (pH=5) electrolyte solution in a potentiodynamic way (10 cycles, E=?0.2-(+0.8) V vs. SSCE; v=100 mV/s).

[0112] Fe content of the material formed: 13.3% (atom %).

Example 11

[0113] Deposition of the Bisphenol a Layer Before the Ferrate Treatment [0114] (1) Electrochemical deposition of PEDOT layer on gold substrate, under galvanostatic conditions (j=0.2 mA/cm.sup.2, t=3600 s) from 0.01 M EDOT/0.1 M Na.sub.2SO.sub.4 electrolyte (counter electrode: Pt, reference electrode: SCE). [0115] (2) Deposition of poly(bisphenol A) layer from 100 ppm BPA/0.5 M H.sub.2SO.sub.4 (pH=0.6) electrolyte solution in a potentiodynamic way (10 cycles, E=?0.1-(+1.0) V vs. SSCE; v=100 mV/s). [0116] (3) The reduction of the deposited PEDOT/PBPA layer was carried out in a 0.1 M Na.sub.2SO.sub.4 (pH=5) solution (E=?0.3 V, t=120 s). A sodium chloride saturated calomel electrode (SSCE) was used as a reference electrode. [0117] (4) The reduced PEDOT layer was immersed in a 0.05 M K.sub.2FeO.sub.4/KOH solution (t=30 s; pH=14-10*). [0118] (5) Steps (2) and (3) were performed 10 times consecutively.

[0119] *: The pH is decreasing during the process.

[0120] Fe content of the material: 0.5 atom %.

[0121] III. Synthesis of PANI Film-Containing Composites

[0122] Instead of applying galvanostatic polymerizationas in the synthesis of PEDOT filmsin case of certain polymers, e.g., polyaniline, potentiodynamic deposition is recommended, as galvanostatic deposition is less efficient. Further steps of preparation are the same as those discussed for PEDOT.

Example 12

[0123] (1) Electrochemical deposition of PANI film on gold substrate in a potentiodynamic way [0124] (E=0.2-0.8 V, v=100 mV/s, 40 cycles) from 0.2 M aniline/0.5 M H.sub.2SO.sub.4 electrolyte (counter electrode: Pt, reference electrode: SCE). [0125] (2) The deposited PANI layer was reduced in a 0.1 M Na.sub.2SO.sub.4 (pH=5) solution [0126] (E=?1.3 V vs. SSCE; t=300 s). [0127] (3) The reduced PEDOT layer was immersed in a 0.05 M Na.sub.2FeO.sub.4/NaOH solution (pH=14-10*, t=300 s).

[0128] *: The pH is decreasing during the process.

[0129] The incorporation of iron into the polymer film is observable as the initially bright green polymer layer turns into purple-bluish after the treatment.