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We present an efficient, highly selective and binder free non-enzymatic glucose sensor based on polyaniline@copper-nickel (PANI@CuNi) nanocomposite. PANI@CuNi nanocomposites with different loading ratio of nanoparticles (1: 025, 1: 0.33, 1: 05 and 1: 1) were prepared by mixing solution of PANI, synthesized through inverse emulsion polymerization method, and CuNi nanoparticles, synthesized through polyol process. The as prepared PANI@CuNi nanocomposites were coated on glassy carbon substrate without binder for non-enzymatic glucose sensing. A considerable increase in the active surface area of the electrode occurred after coating of this material. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and chronoamperometry demonstrated that PANI@CuNi nanocomposite with 1: 0.5 ratio could be a good choice to be used as electrode material for non-enzymatic glucose sensing. The PANI@CuNi modified electrode exhibited high sensitivity (1030 μA mM−1 cm−2), good lower detection limit (0.2 μM) and a linear range of 5.6 mM (R2 = 0.992) with additional advantage of excellent selectivity, high stability and effective detection in real blood samples.

In this work nickel modified polymer composites have been synthesized electrochemically for methanol electrooxidation on platinum and graphite electrodes. Ni (II) ions were incorporated on polyaniline and poly (o-aminophenol)(PANI/POAP) bilayer structure from 0.1 M Nickel sulphate hexahydrate solution at open circuit potential (OCP).TheNi (II) deposited composites were characterized with Fourier Transform Infrared (FTIR) spectroscopy, Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). Cyclic voltammetry characterization exhibits stable redox pair of Ni+3/Ni+2 for both electrodes. Fourier transform infrared spectroscopy was used for functional group analysis. Ni (II) peaks were observed in the region of 400–700 cm−1 along with peaks at 1102 cm−1 and 1400–1600 cm−1 for polyaniline and phenoxazine units. The Ni-polymer composite on platinum and graphite electrode followed different phenomenon for methanol electroxidation in alkaline media. The cyclic voltammetry results showed significantly large methanol oxidation on platinum substrate with charge storage capacity of 196 μ F/cm2 for 1.5 M methanol in alkaline media as compared to 8.306 μF/cm2 of graphite. The diffusion controlled linear response for increase rate of methanol concentration has been obtained for Ni (II)/PANI/POAP-Pt. The electrochemical impedance spectroscopy (EIS)results indicated increase in charge storage capacity from 10−4F/cm2 to 10−3 F/cm2 with increasing potentials at lower frequency region.The phase shift was observed from 60–40 degrees for increased potentials at low frequency range in EIS analysis. The increased conductive behavior from 10−5 to 10−2 s/cm2 has been obtained fornickel modified polymer composite at higher frequency region in EIS analysis.

Polyaniline/Poly(o-aminophenol) (PANI/POAP) bilayered films were deposited by electro polymerization on platinum (Pt) and graphite (Gra) electrodes for methanol oxidation in direct methanol fuel cells. The chemical composition of bilayered structure was characterized by Fourier transform infrared (FTIR) spectroscopy. Results demonstrated the presence of FTIR peaks associated to PANI and POAP constituents confirming the bonding of PANI and POAP in the bilayered composite structure. The electrochemical properties of PANI/POAP electrodes were examined in pure and sulfuric acid mixed methanol solutions using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). PANI/POAP-Gra electrode showed less reactivity towards methanol oxidation, as well as poor stability upon repeated cycling. On the other hand, PANI/POAP-Pt electrode exhibited superior performance with high methanol oxidation current (Ia), capacitance (C), and specific capacitance (Cs). In addition, PANI-POAP-Pt electrode was found better than PANI-POAP-Gra electrode in terms of operation stability based on continuous cycling in methanol up to 100 cycles. The dielectric properties and AC conductivity (σac) of the PANI/POAP-Pt electrode with respect to the applied potential have been discussed.

Platinum-free counter electrodes are crucial for developing cost effective solar energy harvesting technology. We describe here the fabrication of efficient platinum free FTO counter electrodes for dye sensitized solar cells based on pristine polyaniline, polyaniline doped with sulfuric acid, ammonuim lauryl sulfate, as well as binary doped with sulfuric acid and ammonium lauryl sulphate. The characteristics of these counter electrodes were analyzed using cyclic voltammetry, photocurrent density–voltage and electrochemical impedance spectroscopy measurements. At optimized fabrication conditions, the counter electrode shows significantly high photoelectric conversion efficiency of 4.54% compared to 4.03% for reference platinum counter electrode. Charge transfer resistance at the interface between electrolyte and counter-electrode is also decreased for the optimized polyaniline based counter electrode. Furthermore, the device presented characteristics of multiple start/stop ability and fast activity. The simple preparation procedure, low cost and improved photoelectric properties permit fabricated counter electrode to be a reliable alternative for dye sensitized solar cells.

This paper evaluates comparatively the behavior of 2-methylaniline (2-MA) and 3-methylaniline (3-MA) in a UV–vis spectroelectrochemical study of their homo- as well as copolymerization with 1,2-diaminobenzene (1,2-DAB). The homopolymers poly(2-methylaniline) (P2-MA) and poly(3-methylaniline) (P3-MA) show similar spectroelectrochemical properties. However, differences were observed in the properties between the copolymers of 2-MA and 3-MA with 1,2-DAB that could be due to the variation in the monomer units and orientation along the copolymer chains. The formation of head-to-tail coupled p-aminodiphenylamine (PPD) type of mixed dimers/oligomers, presumably resulting from the dimerization of 1,2-DAB and 2-MA or 3-MA cation radicals, is proposed. An absorption peak around λ = 497 nm in the UV–vis spectra is assigned to these intermediates. A mechanism is proposed for the growth of the copolymers. Characteristic UV–vis features of the copolymers have been identified and their dependencies on the electrode potential are discussed. Clear variations in spectroelectrochemical properties of the materials from mixed solutions can be observed just by varying the concentration of 1,2-DAB and by replacing 3-MA with 2-MA in the feed. One of the possible reason for the difference in the properties of the copolymers of 2-MA and 3-MA might be the effect of the electron-donating methyl group in meta-position resulting in an increased electron density in the second meta-position contributing to meta-coupling of radical cations.

An attempt has been made to evaluate comparatively the behavior of 2-methylaniline (2MA) and 3-methylaniline (3MA) during electrochemical homo- and copolymerization. As comonomer in the copolymerization bath with 2MA and 3MA 1,2-diaminobenzene (1,2-DAB), an aromatic diamine, was selected. Cyclic voltammetry was used both for the electrochemical synthesis and characterization of the homopolymers and copolymers on a gold electrode. In the copolymerization bath mixed solutions of the monomers having different concentrations of 1,2-DAB and a constant concentration of 2MA or 3MA were used. The voltammograms exhibit different behavior for different concentration ratios of the monomer in the feed. The homopolymers poly(2-methylaniline) (P2MA) and poly(3-methylaniline) (P3MA) show similar electrochemical properties. However, differences were observed in the properties between the copolymers of 2MA and 3MA with 1,2-DAB that could be due to the variation in the monomer units and orientation along the copolymer chains. The copolymerization of 1,2-DAB seems to be more facilitated when instead of 3MA, 2MA is present as comonomers. The effect of scan rate and pH on the electrochemical activity was studied. The copolymers are surface confined, electroactive and show good electrochemical activity even at pH = 8.0 and pH = 9.0 in case of poly(1,2-DAB-co-3MA) and poly(1,2-DAB-co-2MA), respectively. In situ conductivity measurements further support the differences in the structure of the copolymers of 1,2-DAB with 2MA and 3MA.

A comparative discussion of the electrochemical and spectroelectrochemical properties of poly(o-phenylenediamine) POPD, an aromatic diamine, is presented. In situ conductance measurements show that POPD shows some conductance around the redox peak potentials, i.e. = −0.02 < ESCE < 0.00 V. In situ UV–vis and Raman spectroelectrochemical results suggest that radical cations of polyaniline (PANI)-like segments in POPD backbone might be responsible for imparting conductance to this otherwise nonconducting polymer (as commonly supposed in the literature). The presence of radical cations was confirmed by in situ Raman spectra showing a band at 1390 cm−1 characteristic of a C–N+-stretching vibration having an intermediate single/double bond character and being coupled to quinoid rings/polaronic form of PANI segments in the polymer. Results also reveal that POPD shows a close correlation between its electrochemical and spectroelectrochemical properties in the range of −0.02 < ESCE < 0.00 V, and provide support for the suggested presence of doped PANI-like segments in said potential range.

A comparative discussion of the electrochemical and spectroelectrochemical properties of poly(o-toluidine) POT, a methyl substituted derivative of polyaniline, PANI, is presented. POT exists in various oxidation states and shows an insulator to conductor transition when doped by electrooxidation. The transformation of the polymer film from its non-conducting leucoemeraldine to its conducting emeraldine state and further on to its again non-conducting pernigraniline form was observed with different techniques including cyclic voltammetry, in situ conductivity measurements and in situ UV–vis and Raman spectroelectrochemical methods. Results reveal that POT shows a good correlation between its electrochemical and spectroelectrochemical properties in its different oxidation states.

Electropolymerization of aniline on poly(o-aminophenol)(POAP)-coated gold and indium-doped tin oxide (ITO)-coated glass electrodes yields polyaniline(PANI)/POAP two-layer composite films, exhibiting reversible redox functions in aqueous acidic solution. The PANI deposition on the POAP-coated electrodes was monitored by cyclic voltammetry (CV) and in situ UV–vis spectroelectrochemistry. CV results show that PANI/POAP composite films exhibit better stability as compared to PANI films during potential cycling in aqueous acidic solutions. Characteristic UV–vis and Raman features of the composite films have been identified and their dependencies on the electrode potential are discussed. They were significantly different from the corresponding spectral characteristics of PANI and POAP films alone.

Electroactive copolymers of aniline and o-aminophenol (OAP) with varying concentration ratios prepared by potential cycling in acidic aqueous solutions of the monomers on indium-doped tin oxide (ITO) coated glass and gold electrodes were studied with in situ UV–vis and Raman spectroscopy. Characteristic UV–vis and Raman features have been identified and their dependencies on the electrode potential are discussed. Spectroelectrochemical results reveal the formation of polyaniline-based copolymers at low concentration of OAP in the feed but incorporation of more OAP units into the copolymer with higher concentration of OAP in the comonomer feed. Spectroelectrochemical features are significantly different from those of both homopolymers.