Potentiodynamic and potentiostatic deposition of polyaniline on stainless steel: Electrochemical and structural studies for a potential application to corrosion control

Electrodeposition of Polyaniline on Tantalum: Redox Behavior, Morphology and Capacitive Properties

Polyaniline (PANI) is among the most widely studied conducting polymers due to its potential technological applications in various fields. Recently, PANI-based hybrid materials have played an important role in the development of energy storage and conversion systems. The aim of the present work is the investigation of the simultaneous electrochemical growth of PANI and Ta2O5 on the Ta substrate and the characterization of the morphology, redox behavior and pseudocapacitive properties of the resulting micro- or nanostructured composite thin films. A well-adherent conductive Ta2O5-PANI composite film was first formed using cyclic voltammetry on Ta that facilitates the on-top electrodeposition of single PANI via an autocatalytic mechanism. The electrochemical characterization of the Ta|Ta2O5-PANI|PANI electrodes reveals unique redox properties of PANI not shown previously upon using PANI electrodeposition on Ta. Scanning electron microscopy shows that the morphology of the electrodeposited films comprises nano- or microspheres that may develop into nano- or microrods when the polymerization proceeds. Preliminary evaluation of the capacitive properties of the Ta|Ta2O5-PANI|PANI electrode shows adequately high specific capacitance values as high as 1130 F g-1 (at 9.2 mA cm-2), depending on the electrochemical parameters, as well as adequate stability (~80% retention after 100 cycles), indicating their potential application as energy storage devices.

Corrosion Protection Efficacy of the Electrodeposit of Poly (N-Methyl Pyrrole-Tween20/3-Methylthiophene) Coatings on Carbon Steel in Acid Medium

In this study, poly(N-methylpyrrole-Tween20/3-methylthiophene) coatings were electrodeposited on carbon steel type OLC 45 by electrochemical techniques in oxalic acid solution. Surfactant Tween 20 as a dopant ion employed during electropolymerization can have an important influence on the corrosion protection of this coating by obstructing the penetration of aggressive sulfate ions. The new composite coatings have been analyzed electrochemically, spectroscopically and morphologically by cyclic voltammetry, Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) methods. Corrosion protection consideration of PNMPY-TW20/P3MT-coated OLC 45 has been analyzed by potentiostatic and potentiodynamic polarization, open circuit potential and electrochemical impedance spectroscopy (EIS) measurements in 0.5 M H2SO4 medium. The corrosion rate of PNMPY-TW20/P3MT-coated OLC 45 has been indicated to be ~10 times reduced compared to uncoated OL 45, and the corrosion protection efficiency of the coating is above 90%. The greatest efficacy is achieved by PNMPY-TW20/P3MT composite by electrodeposition at 5 mA/cm2 and 3 mA/cm2 current densities applied and at 1200 mV potential applied in 5:1 and 3:5 molar ratios. The PNMPY-TW20/P3MT coating realized by the galvanostatic method exhibited a non-damaging surveying after 96 h of immersion in the aggressive medium, further verifying its excellent protection capacity. The consequences of the corrosion experiments clearly divulged that PNMPY-TW20/P3MT coatings ensure a very good anticorrosion protection of OLC 45 in aggressive medium.

Dataset for the selection of electrolytes for Electropolymerization of aniline

The most investigated conducting polymer (CP) is polyaniline (PANI)), a promising polymer due to its excellent environmental stability, simplicity of synthesis, and high electrical conductivity [1], [2], [3], [4]. In corrosion protection applications, the PANI film has shown promising potential in protecting active metals such as iron by acting as physical barrier coatings, as a primer layer and as component in a multi-layer coating system [5]. The PANI has an excellent potential to replace the toxic metal, such as chromates, in corrosion protection and is considered a green anti-corrosion candidate [5], [6], [7]. The electrochemical synthesis of PANI coatings on active metals is accomplished by the dissolution of the metal at a potential lower than the monomer oxidation potential [8], [9]. Therefore, electrochemical synthesis of PANI coatings on active metal requires a proper choice of the electrolyte and solvent that should strongly passivate the metal without hindering the electropolymerization process [10], [11]. The data reported here are obtained while the anodic polarization of mild steel (MS) is carried out in succinic acid, sulphanilic acid, sodium orthophosphate, sodium potassium tartrate (Na-K tartrate), and benzoic acid in 3:1 alcohol-water (BAW) solutions [11]. However, the results of electrolytes sodium-potassium tartrate (Na-K tartrate) and benzoic acid in alcohol-water (BAW) are reported for the polymerization of aniline onto MS [11]. The SEM image of MS sample polarized in 0.3 M oxalic acid solution and 0.1 M aniline in 0.3 M oxalic acid is reported as a dataset or a supplementary material of the main manuscript ‘The Effect of Electrolytes on the Coating of Polyaniline on Mild Steel by Electrochemical Methods and Its Corrosion Behaviour [11].’

Electrochemical synthesis and corrosion protection of poly(3-aminophenylboronic acid-co-pyrrole) on mild steel

Synthesis of poly(3-aminophenylboronic acid-co-pyrrole) (p(APBA-co-Py)) is carried out potentiodynamically on a pre-passivated mild steel (MS) surface in an oxalic acid solution containing 3-aminophenylboronic acid (APBA) and pyrrole (Py) monomers. The monomer feed ratio was determined using electrochemical impedance spectroscopy (EIS) and adhesion tests. The p(APBA-co-Py) coating is characterized by electrochemically and spectroscopically comparing with poly(3-aminophenylboronic acid) (p(APBA) and polypyrrole (p(Py) homopolymers. SERS, FTIR, XPS, scanning electron microscopy-wavelength dispersive X-ray and- energy dispersive X-ray spectroscopy results indicate the presence of both APBA and Py segments in the p(APBA-co-Py) backbone. The protective properties of the coating are investigated by Tafel and EIS measurements in a 0.50 M HCl solution. The corrosion resistance of p(APBA-co-Py)-coated MS (66.8 Ω cm²) is higher than that of p(APBA)- and p(Py)-coated, passivated, and uncoated MS. The p(APBA-co-Py) coating embodies the advantageous features of both homopolymers. Py units in p(APBA-co-Py) chains improve the protective property while APBA units carrying the –B(OH)₂ group develop the adhesive property of the layer. EIS results show that the p(APBA-co-Py) coating, due to its homogeneous and compact distribution and the formation of a stable interface, enhanced corrosion resistance of MS by 87.4% for 10 hours in HCl corrosive medium.

Synthesis of poly(3-aminophenylboronic acid-co-pyrrole) (p(APBA-co-Py)) is carried out potentiodynamically on a pre-passivated mild steel (MS) surface in an oxalic acid solution containing 3-aminophenylboronic acid (APBA) and pyrrole (Py) monomers.

Boosting the Utilization and Electrochemical Performances of Polyaniline by Forming a Binder-Free Nanoscale Coaxially Coated Polyaniline/Carbon Nanotube/Carbon Fiber Paper Hierarchical 3D Microstructure Composite as a Supercapacitor Electrode

Nanoscale polyaniline (PANI) is formed on a hierarchical 3D microstructure carbon nanotubes (CNTs)/carbon fiber paper (CFP) substrate via a one-step electrochemical polymerization method. The chemical and structural properties of the binder-free PANI/CNTs/CFP electrode are characterized by field emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. The specific capacitance of PANI/CNTs/CFP tested in a symmetric two-electrode system reaches 731.6 mF·cm^-2 (1354.7 F·g^-1) at a current density of 1 mA·cm^-2 (1.8 A·g^-1). The symmetric supercapacitor device demonstrates excellent cycling performance up to 10,000 cycles with a capacitance retention of 81.4% at a current density of 1 mA·cm^-2 (1.8 A·g^-1). The results demonstrate that the binder-free CNTs/CFP composite is a strong backbone for depositing ultrathin PANI layers at a high mass loading. The hierarchical 3D microstructure PANI/CNTs/CFP provides enough space and transporting channels to form an efficient electrode-electrolyte interface for the supercapacitance reaction. The formed nanoscale PANI film coaxially coated on the sidewalls of CNTs enables efficient charge transfer and a shortened diffusion length. Hence, the utilization efficiency and electrochemical performances of PANI are significantly improved. The rational design strategy of a CNT-based binder-free hierarchical 3D microstructure can be used in preparing various advanced energy-storage electrodes for electrochemical energy-storage and conversion systems.

Electrochemical Preparation of Polyaniline- Supported Cu-CuO Core-Shell on 316L Stainless Steel Electrodes for Nonenzymatic Glucose Sensor

In this article, we reported the elaboration of a nonenzymatic glucose sensor based on the polyaniline-supported Cu-CuO core-shell structure prepared on the 316L stainless steel electrode by electrochemical methods. In the first step, polyaniline (PANI) film was electrodeposited on the 316L substrate from a solution of 0.1 M aniline and 0.5 M sulfuric acid in absolute ethanol by the cyclic voltammetry (CV) method. In the second step, the copper particles were electrodeposited on the PANI film from CuCl2·2H2O 0.01 M precursor prepared in a KCl 0.1 M solution by the CV method. In the third step, Cu particles were partially oxidized to CuO by the CV method in a NaOH 0.1 M electrolyte to form a Cu-CuO core-shell structure supported on the PANI film. The as-prepared electrode (Cu-CuO/PANI/316L) was used to detect glucose in a NaOH 0.1 M solution. The Cu-CuO/PANI/316L sensor exhibited a linear range of 0.1–5 mM (R2 = 0.995) with a detection limit of 0.1 mM (S/N = 3) and high sensitivity of (25.71 mA·mM−1·cm−2). In addition, no significant interference was observed from sucrose, maltose, lactose, and ascorbic acid. The results showed that the polyaniline-supported Cu-CuO core-shell structure has the potential to be applied as an electrode material for the nonenzymatic glucose sensor.

Permselectivity and thickness-dependent ion transport properties of overoxidized polyaniline: a mechanistic investigation

We report here the permselectivity of overoxidized polyaniline obtained using anodic polarization of polyaniline on glassy carbon electrodes. The contrasting redox behavior of overoxidized polyaniline coated electrodes towards [Fe(CN)₆]^3- and [Ru(NH₃)₆]³⁺ has been analyzed using cyclic voltammetry, hydrodynamic voltammetry and electrochemical impedance spectroscopy. This permselectivity vis a vis anion exclusivity arises from the incorporation of counter anions rather than by the formation of new functional groups in the polymer upon overoxidation - as inferred from FT Raman and UV-Visible spectral data. The surface charges of the polymeric films are also deduced from the zeta potential analysis. The thickness-dependent anion exclusion behavior of overoxidized polyaniline is quantitatively interpreted using diffusion coefficient measurements with rotating disc electrodes. The mechanism pertaining to the non-trivial role of film thickness in influencing anion exclusion is confirmed by additional impedance spectroscopy carried out during the overoxidation of polyaniline.

Polyaniline and poly(flavin adenine dinucleotide) doped multi-walled carbon nanotubes for p-acetamidophenol sensor

A conductive biocomposite film (MWCNTs-PANIFAD) which contains multi-walled carbon nanotubes (MWCNTs) along with the incorporation of poly(aniline) and poly(flavin adenine dinucleotide) co-polymer (PANIFAD) has been synthesized on gold and screen printed carbon electrodes by potentiostatic methods. The presence of MWCNTs in the MWCNTs-PANIFAD biocomposite film enhances the surface coverage concentration (Gamma) of PANIFAD and increases the electron transfer rate constant (k(s)) to 89%. Electrochemical quartz crystal microbalance studies reveal the enhancements in the functional properties of MWCNTs and PANIFAD present in MWCNTs-PANIFAD biocomposite film. Surface morphology of the biocomposite film has been studied using scanning electron microscopy and atomic force microscopy. The surface morphology results reveal that PANIFAD incorporated on MWCNTs. The MWCNTs-PANIFAD biocomposite film exhibits promising enhanced electrocatalytic activity towards the oxidation of p-acetamidophenol. The cyclic voltammetry has been used for the measurement of electroanalytical properties of p-acetamidophenol by means of PANIFAD, MWCNTs and MWCNTs-PANIFAD biocomposite film modified gold electrodes. The sensitivity value of MWCNTs-PANIFAD film (88.5 mA mM(-1)cm(-2)) is higher than the values which are obtained for PANIFAD (28.7 mA mM(-1)cm(-2)) and MWCNTs films (60.7 mA mM(-1)cm(-2)). Finally, the flow injection analysis (FIA) has been used for the amperometric detection of p-acetamidophenol at MWCNTs-PANIFAD film modified screen printed carbon electrode. The sensitivity value of MWCNTs-PANIFAD film (3.3 mA mM(-1)cm(-2)) in FIA is also higher than the value obtained for MWCNTs film (1.1 mA mM(-1)cm(-2)).