UV Vis Spectroelectrochemical Studies Research Articles

Electrochromic Devices Based on Copolymers of 2,5-Dimethoxyaniline-Diphenylamine

Electrochemical copolymerization of diphenylamine (DPA) with 2,5-dimethoxyaniline (DMA) was performed in aqueous solution for different feed ratios of DPA using cyclic voltammetry. The deposition rate of DPA-DMA copolymer is higher than that of homopolymers (PDPA and PDMA). (DMA-co-DPA) film was deposited using electrochemical polymerization as conducting film on indium tin oxide (ITO) electrode and used as an electrode in an electrochromic device. From the deconvoluted results of X-ray photoelectron spectroscopy, an azeotrope composition of DPA-DMA copolymers exists at DPA feed ratio of 0.5. Poly(3, 4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) was spin-coated on ITO as the other electrode. Polyurethane ionomer (PUI) blended with was used as solid polymer electrolyte. A total solid electrochromic device was assembled as follows: ITO P(DMA-co-DPA) PEDOT:PSS ITO. The columbic efficiency of the devices reached 84% for P(DMA-co-DPA) film with azeotrope composition. The optical contrast of the single electrode and the device were determined by UV-visible spectroelectrochemical studies. A value (31%) of in color upon switching the potential from (vs PEDOT) was noticed for this device. The device was pale yellow at and blue at .

Mixture Design Applied to Electrochemical Polymerization of Ternary Aniline Derivatives on ITO Electrodes

A systematic analysis for electrochemical polymerization of aniline, -toluidine (OTO), and -toluidine (MTO) ternary components on an indium-tin oxide (ITO) electrode was performed. Using an experimental design of mixture, empirical models are fitted and plotted as contour diagrams, which facilitate revealing the synergestic/antagonistic effects between these mixed aniline derivatives. Copolymer produced by electropolymerization of these aniline derivatives in HCl aqueous solution was investigated by cyclic voltammetry (CV), UV-visible spectroelectrochemical study, and scanning electron spectroscopy (SEM). The cyclic voltammogram of the copolymer growth is significantly affected by the composition of monomers. As shown by CV, the mechanism and the rate of the copolymer growth are significantly affected by the composition and concentration of monomers. The SEM results show that a fiber-like form is changed as a consequence of incorporation of OTO/MTO units into the polymer structure. UV-visible spectrum of the copolymer showed three optical transitions at , 440, and for different applied potentials. At isosbestic points of ca. 350 and , a fixed stoichiometric ratio of oxidized to reduced form exists when the polymer film is oxidized successively by applying potentials from vs .

Oligothiophene Bipyridine Alternate Copolymers and Their Ruthenium Metalated Analogues: In Situ ESR and UV−Vis Investigations of Metal−Chain Interactions

In situ electron spin resonance (ESR) and UV-vis spectro-electrochemical studies have been performed on two copolymers consisting of alternating subunits of regioregular head to tail (HT) coupled 3-octylthiophene tetramer and 2,2'-bipyridine subunits (P4) or 3-octylthiophene hexamer subunits of the same regioregularity and 2,2'-bipyridine subunits (P6). Both P4 and P6 have been investigated in their metal-free form as well as in the ruthenium(II) metalated form (P4-Ru and P6-Ru). P4 and P6 in the p-doped state exhibit a clear ESR signal characteristic of the presence of polarons in the oligothienylene subunits. In the case of P4, no recombination of polarons into bipolarons is observed, whereas the recombination process takes place in P6. The formation of bipolarons is well-rationalized in terms of the conjugation length, and it seems clear that the higher length of the oligothiophene subunit in P6( )()stabilizes bipolarons(.)() The same effect, is induced by the coordination of -Ru(bpy)(2)(2+) to the bipyridine unit in the metalated form of both polymers, which results in an increase of the conjugation length. Important information is gained from the analysis of the ESR spectra of both nonmetalated and metalated in the oxidized (p-doped) and reduced (n-doped) forms. In the p-doped state both nonmetalated and metalated polymers reveal the presence of a narrow ESR line characteristic of the mobile spin carriers in the polymer matrix. The oxidation of the metal center occurs at higher potentials and leads to an irreversible destruction of the system. To the contrary, in the reduced (n-doped) state the ESR lines of the nonmetalated and metalated polymers markedly differ. A significant line broadening with simultaneous change of the g-value is caused by spin-orbit coupling phenomenon induced by the presence of the coordinating metal. Finally, the observation of a clear polaronic band in the UV-vis spectrum of p-doped P4 and its strong dependence on the applied potential can be clearly correlated with the potential induced changes in the ESR spin density. The same applies to P4-Ru, where the changes in the polaronic and bipolaronic bands can also be correlated with the ESR spin density changes.

Novel electrochromic devices based on composite films of poly(2,5-dimethoxyaniline)-waterborne polyurethane

Waterborne polyurethane (WPU) was spin-coated on indium tin oxide (ITO) coated glass. Poly(2,5-dimethoxyaniline) (PDMA) was deposited using electrochemical polymerization as conducting composite film on the above WPU/ITO electrode and used as an electrode in an electrochromic device assembly. Tungsten oxide (WO 3) coated ITO glass was used as the other electrode with LiClO 4 doped gelled polyethylene oxide (PEO) as polymer electrolyte. The configuration of an electrochromic device was assembled: ITO/WPU-PDMA||LiClO 4-PC-PEO (400,000)||WO 3/ITO, where PC represents propylene carbonate. The characterization of the single electrodes, ITO/WPU-PDMA composite, ITO/WO 3, and the device was performed by using cyclic voltammetry. The columbic efficiency (CE) of the ITO/WPU-PDMA composite and ITO/WO 3 electrodes were close to 100%. The optical contrast of the single electrodes and the device were determined by UV–vis spectroelectrochemical studies. A visible contrast in color upon switching the potential from −1.50 to +1.50 V was noticed for the device. The device was pale yellow at −1.5 V and dark green at +1.5 V. The CE of the device was 91%. Double potential chronamperomtry was used to determine the response time of coloring and bleaching processes. The bleaching process was found to be faster than coloring. The stability of the device was established by polarizing the device and recording the UV–vis spectrum in open circuit conditions. Bleaching state is more stable than coloring state.

Studies on monitoring the composition of the copolymer by cyclic voltammetry and in situ spectroelectrochemical analysis

Electrochemical copolymerization of diphenylamine (DPA) with ortho-toluidine (OT) was carried out in 4 M sulphuric acid medium by cyclic voltammetry. Cyclic voltammograms (CVs) of the copolymer films were recorded to deduce the electrochemical characteristics. In situ UV–visible spectroelectrochemical studies on copolymerization were carried out using indium tin oxide (ITO) coated glass plate as working electrode for different feed ratios of DPA and OT. UV-visible spectral characteristics show clear dependencies on the molar feed composition of DPA or OT used in electropolymerization. Derivative cyclic voltabsorptogram (DCVA) was deduced at the wavelength corresponding to the absorption by the intermediate species and used to identify the intermediates generated during the electropolymerization. The molar composition of DPA and OT units in the copolymer for the copolymers synthesized with different molar feed ratios of DPA and OT was determined by UV–visible spectroscopy. Reactivity ratios of DPA and OT were deduced by using Fineman–Ross and Kelen–Tudos methods and the observed differences in the composition of DPA/OT in the copolymers were correlated with CV characteristics and results obtained from in situ spectroelectrochemical studies.

Fe 3+ ion sensing characteristics of polydiphenylamine—electrochemical and spectroelectrochemical analysis

Polydiphenylamine (PDPA) film was deposited on platinum/indium tin oxide coated glass (ITO) electrode in aqueous acidic medium and analyzed for the changes in redox characteristics in the presence of acidified iron (III) chloride (FeCl 3). PDPA seems to capture Fe 3+ ions and further transforms into Fe 2+ ions through interaction with its redox binding sites, as confirmed through results from cyclic voltammetry and UV–vis spectroscopic studies. The redox behavior for the PDPA film modified with Fe 3+ ions was evaluated through in situ UV–vis spectroelectrochemical studies. In situ studies demonstrate that PDPA is partially reduced in the presence of Fe 3+ ions and the redox transformation was almost reversible. Modified PDPA film electrode showed Nernstian potential response for Fe 3+/Fe 2+ redox process and such modification is expected to be suitable for sensor applications.

Preparation and structural investigations of electrochromic nanosized NiO x films made via the sol–gel route

The main aim of this work was to study the influence of the NiSO 4 precursor and the annealing temperature on the electrochemical stability and electrochromic response of dip-coated Ni-oxide films. Nickel hydroxide was precipitated from the precursor solution using lithium hydroxide and the slurry was then peptized with acetic acid. Dynamic thermogravimetric measurements made on thin films showed that the decomposition and the formation of Ni-oxide phase differed for powders and films. The results showed that the films annealed at 270 °C (at which the acetate groups decomposed) consisted of cubic (space group Fm3m) NiO grains (2–3 nm, TEM measurements) having monodentately coordinated sulfate groups (IR spectrum). Electrochemical and in situ UV–visible spectroelectrochemical studies of the Ni-oxide films (NiSO 4 precursor, 270 °C) revealed that the photopic transmittance in the colored state (3rd cycle) is 66% and 89% in the bleached state. Cycling (100th cycle) reduced the transmittance of the films in the colored state to 50%, while the bleached films retained their high transmittance (89%). The coloration efficiency of the films was 35–41 cm 2 C −1 depending on the number of cycles. The evolution of the Ni 3+–O stretching vibration (transversal optical mode) of the films in the charged state was followed by the help of ex situ infrared spectroelectrochemical measurements.

In situ resonance micro-Raman and UV–visible spectroelectrochemical studies of an electrochromic device with an I 3−/I − redox sol–gel electrolyte

An all-sol–gel electrochromic (EC) device was constructed of electrochromic WO 3 and transparent Pt films, both deposited on conductive glass electrodes encapsulating a gel electrolyte with an I 3 −/I − redox couple. WO 3 films (200–400 nm) were deposited by the dip-coating technique from peroxopolytungstic acid sols. The films consisted of nanocrystalline WO 3 grains of dimensions 20–30 nm having monoclinic structure. The gel redox I 3 −/I − electrolyte, which was made via the sol–gel route, consisted of an organic phase (poly(propyleneglycol), PPG, M W=4000) covalently bonded via urea bridging groups to a silica phase. Gelation was performed with acetic or valeric acid. The functioning of the device was studied by the micro-resonance Raman spectroscopic technique, focusing the laser excitation line ( λ=647 nm) on the electrolyte encapsulated in the EC device. Variation in the potential from −2 to 2 V (scan rate 5 mV s −1) resulted in changes of the intensity of the symmetric stretching resonance Raman mode of I 3 − ions ( ν s(I 3 −)) and was accompanied by variation in the background Rayleigh scattering. From this, we concluded that the intercalation/deintercalation of K + ions in the WO 3 film was accompanied by an increase/decrease in the I 3 − ion concentrations and reversible dissociation/association of the KI microcrystallites existing in the redox electrolyte.

Voltammetric and spectroelectrochemical studies on 4-aminophenol at gold electrodes in aqueous and organic media

Voltammetric and UV–Vis spectroelectrochemical studies on 4-aminophenol (4-AP) at gold electrodes have been carried out in conventional electrochemical and in novel spectroelectrochemical cells. As base electrolytes acetonitrile with 10 −2 M tetrabutylammonium hexafluorophosphate as supporting electrolyte and acetate buffer (pH 4.6) solutions have been used. 4-AP was electrochemically oxidized at gold electrodes at potentials >+0.1 V in aqueous solutions and at potentials >+0.5 V in acetonitrile solutions. The formation of an oxidation product has been characterized in situ by UV–Vis spectroscopy in a novel optical thin-layer spectroelectrochemical cell.

Electrochemical Synthesis and Spectroelectrochemical Characteristics of Pyrrole ­ 2 , 2 ′ -Dithiodianiline Copolymers

Pyrrole copolymer produced by coelectropolymerization of pyrrole (Py) and -dithiodianiline (DTDA) in organic medium (propylene carbonate, PC) was investigated by cyclic voltammetry, UV-visible spectroelectrochemical study, infrared spectroscopy, and scanning electron spectroscopy (SEM). The cyclic voltammogram of the copolymer grown from nonaqueous media containing an electrolyte is significantly affected by DTDA concentration in the deposition solution. The electropolymerization rate of pyrrole is decreased upon addition of DTDA in the growth solution. This involves the possible branched structure for the copolymer. SEM was used to determine the morphological behavior of the copolymer. The results show that a branch as a consequence of incorporation of DTDA units resulting in -S-S- links in the polypyrrole structure. UV-visible spectrum of the copolymer showed three optical transitions at 540, and 800 nm for different applied potentials. At 425 nm, a fixed stoichiometric ratio of oxidized to reduced form exists when the P(Py-DTDA) copolymer film is oxidized successively by applying potentials, but such a ratio did not exist in PPy film. © 2003 The Electrochemical Society. All rights reserved.

In situ UV–visible spectroelectrochemical studies on the copolymerization of diphenylamine with ortho-methoxy aniline

UV–visible spectroelectrochemical studies on copolymerization of diphenylamine (DPA) with ortho-methoxy aniline (OMA) were carried out for different feed ratios of DPA and OMA using indium tin oxide (ITO)-coated glass as working electrode. The UV–visible spectra show clear dependencies on the molar feed composition of DPA or OMA used in electropolymerization. Derivative cyclic voltabsorptogram (DCVA) was deduced at the wavelengths corresponding to the absorption by the intermediate species and used to confirm the intermediates generated during the electropolymerization. The composition of DPA and OMA in the copolymer for the copolymers synthesized with different molar feed ratios of DPA and OMA was determined by UV–visible spectroscopy. Reactivity ratios of DPA and OMA were deduced by using Fineman–Ross and Kelen–Tudos methods and correlated with spectroelectrochemical results.

Synthesis and characterization of soluble conducting poly(aniline-co-2, 5-dimethoxyaniline)

Copolymers of 2,5-dimethoxyaniline (DMA) with aniline (ANI), poly(DMA-co-ANI), were prepared for different molar feed compositions of DMA/ANI ( f DMA/ f ANI) by chemical oxidative polymerization using ammonium persulfate as oxidant. The copolymers were characterized by elemental analysis (EA), cyclic voltammetry (CV), Fourier transfer infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). EA results show that molar composition of DMA units ( F DMA) increased with increasing f DMA up to 0.60. A compositional drift in F DMA was noticed when the feed ratio of DMA was increased beyond 0.60. The redox characteristics of the copolymers with different F DMA were found to show variations than PDMA and PANI. UV–Visible spectroelectrochemical studies, TGA and FTIR spectroscopic analysis were used to identify the differences in the optical, thermal properties and structure between the copolymers and PDMA or PANI. The conductivity of the copolymer was found to decrease with increasing F DMA. The copolymers were soluble in N-methylpyrroldione, dimethylformamide, tetrehydrofuran and acetone. The solubility of the copolymers increased with increasing F DMA. The presence of –OCH 3 groups in the phenyl ring of DMA units induced easy oxidation and better solubility for the copolymers in comparison with PANI.

Electrochemical and Spectroelectrochemical Studies on Copolymerization of Diphenylamine with 2,5-Diaminobenzenesulfonic Acid

Electrochemical copolymerization of diphenylamine (DPA) with 2,5-diaminobenzenesulfonic acid (DABSA) was carried out in aqueous 4 M by employing cyclic voltammetry (CV). Copolymer films were grown for different molar concentration ratios of DPA and DABSA. Electrochemical homopolymerization of DPA alone was also carried out under similar conditions. UV-visible spectroelectrochemical studies were performed to add evidence for copolymer formation when electropolymerization was performed with DPA and DABSA. A growth equation for the deposition of copolymer film was deduced as where is the number of cycles in CV, by utilizing the charge associated with film deposition. X-ray photoelectron spectroscopy was used to find the elemental composition of copolymer and changes in redox characteristics of the copolymer in comparison with poly(diphenylamine). © 2002 The Electrochemical Society. All rights reserved.

Poly(2,5-dimethoxyaniline) based electrochromic device

Poly(2,5-dimethoxyaniline) (PDMA) was deposited as conducting film on indium tin oxide (ITO) coated glass and used as an electrode in an electrochromic device assembly. Film of tungsten oxide (WO 3) on ITO glass was used as the other electrode with LiClO 4 doped gelled polyethylene oxide (PEO) as polymer electrolyte. An electrochromic device with the following configuration was assembled: ITO/PDMA∥LiClO 4–PC–PEO (400,000)∥WO 3/ITO. Cyclic voltammetry was used to characterize the single electrodes, ITO/PDMA, ITO/WO 3, and the device. The coulombic efficiency (CE) of the ITO/PDMA and ITO/WO 3 electrodes were close to 100%. The optical contrast of the single electrodes and the device were determined by UV–visible spectroelectrochemical studies. A visible contrast in color upon switching the potential from −1.50 to +1.50 V was noticed for the device. The device was pale yellow at −1.50 V and dark green at +1.50 V. The CE of the device was 92%. Double potential chronamperomtry was used to determine the response time of coloring and bleaching processes. The bleaching process was found to be faster than coloring. The stability of the device was established by polarizing the device and recording the UV–visible spectrum in open circuit conditions. Bleaching state is more stable than coloring state.

In situ UV–visible spectroelectrochemical studies on the copolymerization of diphenylamine with anthranilic acid

In situ spectroelectrochemical studies were carried out on the polymerization of diphenylamine (DPA) and copolymerization of DPA with anthranilic acid (AA). Electropolymerization was performed in aqueous 2 M H 2SO 4 by applying a constant potential (0.80 V) on indium tin oxide (ITO)-coated glass electrode. Spectral characteristics were followed for various feed ratios of the comonomers (DPA and AA) at different polymerization times. Two types of cation radicals could be observed for the electropolymerization with mixture of DPA and AA, corresponding to anilinium-type and N, N′-diphenylbenzidine-type, respectively. UV–visible spectra recorded for copolymerization inform that the peak position corresponding to DPB + showed clear dependence on AA concentration in the feed, signifying the changes in the overall oxidation states of the polymer as a result of incorporation of AA units in the copolymer. The FTIR spectral analysis of the copolymer clearly reveals the incorporation of AA units into the polymer backbone during polymerization. The presence of a band at 1650 cm −1 in FTIR spectra corresponding to the –CO group of AA units and the improvement in thermal stability of the copolymer as observed from thermogravimetric analysis (TGA) favor the incorporation of AA units in the copolymer.

Syntheses, redox and UV–Vis spectroelectrochemical properties of mono- and dinuclear tris(pyrazolyl)borato-oxomolybdenum(IV) complexes with pyridine ligands

Reaction of [Mo VI(Tp Me,Me)(O) 2Cl] with a variety of pyridine-based ligands [pyridine (py), 4,4′-bipyridine (bpy), 4-phenylpyridine (phpy) and 1,2′-bis(4-pyridyl)ethene (bpe)] in toluene in the presence of Ph 3P affords the mononuclear oxo-Mo(IV) complexes [Mo(Tp Me,Me)(O)Cl(L)] (L=py, phpy or monodentate bpy; abbreviated as Mo(py), Mo(phpy) and Mo(bpy), respectively) and the dinuclear complexes [{Mo(Tp Me,Me)(O)Cl} 2(μ-L)] (L=bpy, bpe; abbreviated as Mo 2 (bpy), Mo 2 (bpe), respectively). The complex Mo 2 (bpy), together with the by-product [{Mo(Tp Me,Me)(O)Cl} 2(μ-O)], have been crystallographically characterised. Electrochemical studies on the oxo-Mo(IV) complexes reveal the presence of reversible Mo(IV)/Mo(V) couples at around −0.3 V versus ferrocene/ferrocenium in every case. For the dinuclear complexes Mo 2 (bpy) and Mo 2 (bpe) these redox processes are coincident, indicating that they are largely metal-centred and not significantly delocalised across the bridging ligand. In contrast, Mo 2 (bpe) alone shows two reversible reductions, separated by 320 mV; these could be described as ligand-centred reductions of the bpe bridge, or as Mo(IV)/Mo(III) couples which—because of their separation—are substantially delocalised onto the bridging ligand. UV–Vis spectroelectrochemical studies using an OTTLE cell at 243 K revealed that oxidation of the complexes results in spectral changes (collapse of the Mo(IV) d–d transitions, loss in intensity of the Mo→pyridine MLCT transition) consistent with the formation of a Mo(V) state following metal-centred oxidation, but that one-electron reduction of Mo 2 (bpe) results in appearance of numerous intense transitions more characteristic of a ligand radical following ligand-centred reduction.

Resonant Raman spectroscopy as a tool for determining the formation of a ladder structure in electropolymerized poly(5-amino-1-naphthol)

Electropolymerization of poly(5-amino-1-naphthol) onto different conducting substrates was studied in HCl, HClO 4, PTSA ( p-toluene sulfonic acid) and HCSA (camphorsulfonic acid) media. In situ UV–vis spectroelectrochemical studies have shown spectral changes that demonstrate that the oxidation process is accompanied by the formation of polaronic and bipolaronic structures due to the ejection of electrons from the polymeric matrix. Resonance Raman spectroscopy was used to follow structural changes that occur during the redox processes of the polymer and it allows us to infer the formation of imine groups and the possible ‘ortho’ coupling during electropolymerization.

Electrochemical copolymerization of 1-naphthylamine with aniline and o-toluidine

Abstract Copolymers of 1-naphthylamine (NPA) with aniline (ANI) and o -toluidine (OT) were deposited on platinum electrode in 1 M perchloric acid (HClO 4 ) through cyclic voltammetry. The cyclic voltammograms of the copolymer showed a dominant redox couple at a midpoint potential of ca. 0.38 V with a peak separation ranging from 40 to 100 mV. Copolymerization was found to be possible only at low NPA to ANI or OT ratio. UV–visible spectroelectrochemical study on the copolymer films prepared using different feed ratios of NPA revealed the presence of NPA units in varying proportion in the copolymer. The copolymers possess both electrochemical and spectroelectrochemical properties of PNPA and PANI/POT.

An in situ spectroelectrochemical investigation of the copolymerization of diaminobenzenesulfonic acid with aniline and its derivatives

In situ UV-Visible spectroelectrochemical studies on the copolymerization of diaminobenzenesulfonic acid (DABSA) with aniline (ANI), o-toluidine (OT) and N-methyl aniline (NMA) were carried out potentiostatically in aqueous 1.0 M H 2SO 4 solutions containing the mixture of monomers (DABSA and ANI/OT/NMA) at an optically transparent electrode. Copolymerization studies were performed for different feed ratios of the comonomers. Polymerization of DABSA was also carried out to bring out the differences in the spectral characteristics between homopolymerization and copolymerization. UV-Visible spectra were recorded at various timer intervals during copolymerization and homopolymerization of DABSA. Four absorption bands were noticed for the copolymerization in contrast to the three bands for homopolymerization. The appearance of bands at 672, 633 and 668 nm for copolymerization of DABSA with ANI, OT and NMA, respectively, are attributed to the exitonic transitions associated with these monomer units in the copolymer. The exitonic band of PANI/PANI derivative units that appeared during copolymerization was markedly influenced by the presence of sulfonic acid groups in the copolymer. This was demonstrated by observing its influence in the absence of applied potential and also by following the changes in the band positions through spectroelectrochemical studies on the copolymerization of DABSA with ANI or OT or NMA. The dependences of absorbances on time at the wavelengths corresponding to polaronic and exitonic transitions of the polymers were deduced. The decrease in absorbances of the exitonic band arising from the dedoping caused by sulfonic acid groups in the polymer showed variations in the copolymerization of DABSA with ANI, OT and NMA. The following trend was noticed ANI>NMA>OT.

In situ, UV–Vis spectroelectrochemical studies on the initial stages of copolymerization of aniline with diphenylamine-4-sulphonic acid

In situ, spectroelectrochemical studies on the copolymerization of aniline (ANI) with diphenylamine-4-sulphonic acid (DPASA) were carried out in 0.5 M H 2SO 4 for different feed ratios of ANI and DPASA using ITO as the working electrode. Studies on homopolymerization of DPASA and ANI were also done independently in 0.5 M sulphuric acid. UV–Vis absorption spectra were recorded concurrently during the copolymerization and homopolymerizations. The intermediate species for the homopolymerization of DPASA and copolymerization with ANI have been identified by spectroelectrochemical studies. The spectroelectrochemical results revealed the formation of an intermediate at the initial stages of copolymerization through the reaction of the DPASA cation radical and the aniline cation radical to result in a head-to-tail dimer. This N-phenyl- para-phenylene diamine (PPD) type of intermediate was assigned to have a peak at 550 nm in the UV–Vis spectra. The assignment of a peak at 550 nm to the intermediate was further confirmed by deducing derivative cyclic voltabsorptogram (DCVA) at 550 nm. The results from constant potential electropolymerization also supported the formation of an intermediate that absorbs at 550 nm