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.
•PANI@CuNi nanocomposite is highly efficient and selective towards glucose oxidation.•The material is electrochemically very active and stable and can offer a good choice as electrode material for binder free non-enzymatic glucose sensor.•The response of the PANI@CuNi nanocomposite coated electrode towards glucose is very rapid.•The PANI@CuNi modified electrode also possesses good lower detection limit (0.2 μM) and a linear range of 5.6 mM (R2 = 0.992) and effective detection in real blood samples.
Density functional theory studies (DFT) have been carried out to evaluate the ability of polyaniline emeraldine salt (PANI ES) from 2 to 8 phenyl rings as sensor for NH3, CO2, and CO. The sensitivity ...and selectivity of nPANI ES among NH3, CO2, and CO are studied at UB3LYP/6-31G(d) level of theory. Interaction of nPANI ES with CO is studied from both O (CO(1)) and C (CO(2)) sides of CO. Interaction energy, NBO, and Mulliken charge analysis were used to evaluate the sensing ability of PANI ES for different analytes. Interaction energies are calculated and corrected for BSSE. Large forces of attraction in nPANI ES-NH3 complexes are observed compared to nPANI ES–CO2, nPANI ES-CO(1), and nPANI ES-CO(2) complexes. The inertness of +CO– in nPANI ES-CO(1) and nPANI ES-CO(2) complexes are also discussed. Frontier molecular orbitals and energies indicate that NH3 changes the orbital energy of nPANI ES to a greater extent compared to CO2, CO(1), and CO(2). Peaks in UV–vis and UV–vis–near-IR spectra of nPANI ES are blue-shifted upon doping with NH3, CO2, CO(1), and CO(2) which illustrates dedoping of PANI ES to PANI emeraldine base (PANI EB). Finally, it is concluded that PANI ES has greater response selectivity toward NH3 compared to CO2 and CO and it is consistent with the experimental observations.
Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations at the UB3LYP/6-31G(d) level have been performed to investigate the tunable nature, i.e., doping and dedoping processes, ...of polypyrrole (PPy). The calculated theoretical data show strong correlation with the recent experimental reports, which validates our computational protocol. The calculated properties are extrapolated to the polymer (PPy) through a second-order polynomial fit. Changes in band gap, conductivity, and resistance of nPy and nPy-X (where n = 1–9 and X = +, NH3, and Cl) were studied and correlated with the calculated vibrational spectra (IR) and electronic properties. Upon doping, bridging bond distance and internal bond angles decrease (decrease in resistance over polymer backbone), whereas dedoping results in increases in these geometric parameters. In the vibrational spectrum, doping is characterized by an increase in the band peaks in the fingerprint region and/or red shifting of the spectral bands. Dedoping (9Py+ with NH3), on the other hand, results in decreases in the number of vibrational spectral bands. In the UV–vis and UV–vis–near-IR spectra, the addition of different analytes (dopant) to 9Py results in the disappearance of certain bands and gives rise to some new absorbances corresponding to localized and delocalized polaron bands. Specifically, the peaks in the near-IR region at 1907 nm for Py+ and 1242 nm for 9Py-Cl are due to delocalized and localized polaron structures, respectively. Upon p-doping, the band gaps and resistance of nPy decrease, while its conductivity and π-electron density of conjugation increase over the polymeric backbone. However, a reversal of properties is obtained in n-doping or reduction of nPy+. In the case of oxidation and Cl dopant, the IP and EA increase, and consequently, there is a decrease in the band gap. NBO and Mulliken charges analyses indicate charge transferring from the polymer in the case of p-type dopants, while this phenomenon is reversed with n-type dopants.
Sensitivity and selectivity of polypyrrole (PPy) toward NH3, CO2, and CO have been studied at density functional theory (DFT). PPy oligomers are used both in the doped (PPy+) and neutral (PPy) form ...for their sensing abilities to realize the best state for gas sensing. DFT calculations are performed at the hybrid functional, B3LYP/6-31G(d), level of theory. Detection/interaction of CO is investigated from carbon CO(1) and oxygen termini of CO CO(2). Interaction energies and charge transfer are simulated which reveal the sensing ability of PPy toward these gases. Furthermore, these results are supported by frontier molecular orbital energies and band gap calculations. PPy, in both the doped and neutral state, is more sensitive to NH3 compared to CO2 and CO. More interestingly, NH3 causes doping of PPy and dedoping of PPy+, providing evidence that PPy/PPy+ is an excellent sensor for NH3 gas. UV–vis and UV–vis–near-IR spectra of nPy, nPy+, and nPy/nPy+–X complexes demonstrate strong interaction of PPy/PPy+ with these atmospheric gases. The better response of PPy/PPy+ toward NH3 is also consistent with the experimental observations.
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 0.1M 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 400–700cm−1 along with peaks at 1102cm−1 and 1400–1600cm−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 196μ F/cm2 for 1.5M methanol in alkaline media as compared to 8.306μF/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 10−3F/cm2 with increasing potentials at lower frequency region.The phase shift was observed from 60–40degrees for increased potentials at low frequency range in EIS analysis. The increased conductive behavior from 10−5 to 10−2s/cm2 has been obtained fornickel modified polymer composite at higher frequency region in EIS analysis.
The eco-friendly and cost-efficient synthesis of polyaniline (PANI) is one of the perplexing tasks in the research horizons of conducting polymers while keeping the desired properties unaffected. The ...present work reports an eco-friendly and comparably cost-efficient pathway for the synthesis of corrosion-resistant, thermally stable, and highly soluble PANI salt using coconut oil as a novel dispersion medium. The PANI salt was optimized by varying the reaction parameters, such as concentration of monomer, oxidant, surfactant, and solvent. The UV/Visible spectra indicated absorption peaks in the range of 344–353, 424–433, and 740–779 nm. The FTIR analysis of PANI salt reveals the stretching of the benzenoid and quinoid rings at 1460 and 1559 nm respectively. X-ray diffraction shows peaks on 2Ө at 19° and 25° which are the characteristic peaks of PANI. PANI salt was found to be soluble in several organic solvents such as 2-propanol, n-Methylpyrolidinone (NMP), and highly soluble in chloroform and Dimethyl sulfoxide (DMSO) up to 7.6 and 6.9% respectively. SEM images and TGA analysis of PANI confirmed the porous morphology like cauliflower and quite thermally stable up to 538 °C respectively. The layer of synthesized PANI shows remarkable corrosion inhibiting behavior on the surface of mild steel which reduces the rate of corrosion up to 82%. Hence, boost up the global economy.
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•Eco-Friendly and Comparably Cost efficient coconut oil as novel dispersion medium.•High solubility of the synthesized PANI in chloroform up to 7.6%.•The synthesized PANI salts possess highest thermal stability than the reported literature.•The synthesized PANI salts are excellent anticorrosion material for mild steel.
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•Successful synthesis of GO-PANI via in situ chemical oxidative polymerization.•Water processable electrode fabrication of GO-PANI composite using Na-carboxy methylcellulose (CMC) as ...binder.•GO-PANI composite fabricated electrode using CMC exhibits superior electrochemical performance.•A high specific capacitance of 1721 F g−1 was observed for GO-PANI composite with 69.8% retention of capacitance even after 1000 voltammetric cycles at 20 mV s−1.
The behaviour of gold electrode modified with polyaniline/graphene oxide composites (PGO) was studied for electrochemical and charge storage properties in aqueous acidic media. The surface of gold electrode was modified with aqueous slurry of PGO by using Carboxymethyl cellulose (CMC) as binder. The intercalation of polyaniline in the GO layers, synthesized by in situ polymerization was confirmed by scanning electron microscopy (SEM). The electrochemical behaviour and charge storing properties were investigated using cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS). A high specific capacitance of 1721 F g−1 was obtained for PGO with 69.8% retention of capacitance even after 1000 voltammetric cycles in the potential range of 0–0.9 V at 20 mV s−1. EIS indicated low charge transfer resistance (Rct) and solution resistance (Rs) values of 0.51 Ω and 0.07 Ω, respectively. This good performance of PGO coated electrode is attributed to the use of CMC binder which generate a high electrode/ electrolyte contact area and short path lengths for electronic transport and electrolyte ion.
The interaction of colloidal species is prominently governed by their surface properties. The adsorption of charged proteins at the surface of the Polyaniline nanotubes (PN) results in the ...electrostatic interactions which can be moulded by controlling the surrounding zeta potential. The zeta potential of PN as a function of pH, charge density and ionic strength was determined and the results are duly explained by 1-pK model and Grahame model as empirical data fits well to these models. Similarly, the surface charge and zeta potential of the 1 NLB antibodies were also determined which later on explained the adsorption of 1 NLB antibodies on PN in aqueous media. The isoelectric point (IEP) of PN showed variation as function of surface coverage by adsorbed 1 NLB antibody mass. These results were utilized to fabricate a label-free impedimetric immunosensor aimed at the detection of hepatitis C (HCV) 1 NLB monoclonal antibodies (anticore mAbs 19D9D6). The bioactive interfacial layer was attained by the immobilization of 1 NLB monoclonal antibodies at the PN which were later on spin coated on ITO substrate for fabricating impedimetric immunosensor. The impedimetric immunosensor shows linear response range of 01 ng mL−1 to 200 ng mL−1 of HCV core antigen concentration with detection limit of 0.02 ng mL−1 (3σ/S). The charge transfer resistance change (Rct) showed an absence of the prominent change depicting the stability of the impedimetric immunosensor whereas the sensitivity of sensor was found to be 12.215 Ω mL ng−1.
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•Polyanilne nanotubes (PN) based label-free impedimetric immunosensor is proposed.•Electrokinetics of PN illuminates the changing chemistry of PN surface due to coverage by adsorbed proteins.•The charge transfer resistance increases with the increase in antigen concentration (Polypeptide 13-40 residue).•Selectivity of 12.215 Ω mL ng-1 was achieved due to the specific nature of 1 NLB interaction with HCV core nucleocapsid polypeptide antigen.
In this study, a gas sensor device was fabricated using the conducting Polypyrrole (Ppy) coated on porous anodized aluminum oxide (PAAO) which acted as substrate. The Ppy was synthesized by the ...chemical oxidation polymerization method. The oxidation of aluminum is carried out using anodization method technique to develop a capacitive substrate that displays large resistance. Afterwards, the substrate is subjected to polypyrrole coating to develop a sensing material for the gas sensor for ammonia detection based on impedimetric response. For gas sensing application, device was fabricated on interdigitated electrode for which prior electrical characterization was carried out via impedance spectroscopy in order to understand its gas sensing characteristics. The values obtained for the resistance and capacitance using the Z′′ spectrum are 13.36 × 106 Ω and 9.08 × 10−11 F, respectively. The ammonia concentration range in which the ammonia sensing was observed through the change in the impedance (Z) or resistance (R) extends from approximately 05 to 95 ppm. The dynamic response and recovery time of Ppy/PAAO based sensor for ammonia gas was ∼6 s which also displayed significant reproducibility with ammonia concentration when subjected to the adsorption–desorption cycles whereas sensitivity of polypyrrole based ammonia sensor was found to be ∼1.74 × 106 Ω per ppm change at 100 Hz, respectively.
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•Ammonia gas sensing device fabricated using the Ppy/PAAO nanocomposite.•Space charge limited conduction (SCLC) dominates the charge transport mechanism.•Enhanced dielectric properties points to the Maxwell-Wagner-Sillars effects.•The dynamic response and recovery time was found to be ∼6 s.•The sensitivity was ∼1.74 × 106 Ω per ppm change at 100 Hz.
Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations have been performed to gain insight into the structure of poly(o-phenylenediamine) (POPD). Both reported structures of ...POPD, ladder (L)- and polyaniline (P)-like, are investigated theoretically through the oligomers approach. The simulated vibrational properties of 5POPD(L) and 5POPD(P) at B3LYP/6-31G (d) along with their assignments are correlated with experimental frequencies. Vibrational spectra show characteristic peaks for both POPD(L) and POPD(P) structures and do not provide any conclusive evidence. Excited-state properties such as band gap, ionization potential, electron affinities, and HOMO–LUMO gaps of POPD(L) and POPD(P) from monomers to five repeating units are simulated. UV–vis spectra are simulated at the TD-B3LYP/6-31+G (d, p) level of theory, supportive to the ladder-like structure as the major contributor. Comparison of the calculated data with the experimental one strongly suggests that the ladder-like structure is the predominant contributor to the molecular structure of POPD; however, a small amount of POPD(P) is also believed to be present.
