Electrochemical Deposition Of Polypyrrole Research Articles

Advanced Procedure of Simultaneous Electrodeposition from a Natural Deep Eutectic Solvent of a Drug and a Polymer Used to Improve TiZr Alloy Behavior.

This paper presents research about the embedding and release of gentamicin from an electrochemical deposition of polypyrrole from ionic liquids such as choline chloride on TiZr bioalloy. The electrodeposited films were morphologically investigated using scanning electron microscopy (SEM) with an EDX module, and polypyrrole and gentamicin were both identified using structural FT-IR analysis. The film's characterization was completed with an evaluation of hydrophilic-hydrophobic balance, with electrochemical stability measurements in PBS and with antibacterial inhibition. A decrease in the value of the contact angle was observed from 47.06° in the case of the uncoated sample to 8.63° in the case of the sample covered with PPy and GS. Additionally, an improvement in the anticorrosive properties of the coating was observed by increasing the efficiency to 87.23% in the case of TiZr-PPy-GS. A kinetic study of drug release was performed as well. The drug molecule might be provided by the PPy-GS coatings for up to 144 h. The highest amount released was calculated to be 90% of the entire drug reservoir capacity, demonstrating the effectiveness of the coatings. A non-Fickian behavior was established as a mechanism for the release profiles of the gentamicin from the polymer layer.

Electrochemical Deposition of Polypyrrole in the Presence of Silanes as Adhesion Promoters.

Polypyrrole adhesion to indium-tin oxide electrodes was improved by adding pre-hydrolyzed alkoxysilanes to the electrodeposition media. The pyrrole oxidation and film growth rates were studied by potentiostatic polymerization in acidic media. The morphology and thickness of the films were studied by contact profilometry and surface-scanning electron microscopy. The bulk and surface semiquantitative chemical composition was studied by Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Finally, the adhesion was studied by scotch-tape adhesion test, where both alkoxysilanes showed a significant improvement in adhesion. We proposed a hypothesis for the improvement in adhesion, that involves the formation of siloxane material as well as in situ surface modification of the transparent metal oxide electrode.

Porous NiCo2O4@Ppy core-shell nanowire arrays covered on carbon cloth for flexible all-solid-state hybrid supercapacitors

Abstract Nanoarray structure materials have drawn much attention because they facilitate the transmission of electrons and shorten ion diffusion path for application in energy storage. In this paper, the porous core-shell NiCo2O4@Ppy nanowire arrays were designed and successfully prepared through hydrothermal treatment assisted with sodium dodecyl sulfate as a template and sequent by electrochemical deposition of polypyrrole. The structural characterization results show that the 8–40 nm thickness of polypyrrole layer is covered on crystalline NiCo2O4 nanowires. The electrochemical tests verified that the unique NiCo2O4@Ppy composite exhibits fast charge transfer kinetics during long charge/discharge process. The specific capacity of the NiCo2O4@Ppy/CC electrode reaches 155.4 mAh g−1 at the density of 1 mA cm−2 and 138 mAh g−1 at 10 mA cm−2. Also, it exhibits the 71% capacity retention ratio after 8000 cycles at 10 mA cm−2. Furthermore, an all-solid-state hybrid supercapacitor, assembled by the NiCo2O4@Ppy/CC as positive electrode, active carbon as negative electrode and PVA/KOH gels as electrolyte, delivers high energy and power density. The excellent electrochemical performance of the core-shell structure NiCo2O4@Ppy reveals the great possibility for the application in high-performance supercapacitors.

Nitrogen-doped carbon fiber/carbon paper supported Co-MoS2 as an efficient catalyst for hydrogen evolution

In this paper, Co-doped MoS2 (Co-MoS2) with various Co/Mo mole ratio (6%–12%) decorated on nitrogen-doped carbon fiber/carbon paper (NCFCP) (Co-MoS2/NCFCP) is fabricated by a solvothermal method as an efficient electrocatalyst for hydrogen evolution reaction (HER). The NCFCP substrate is prepared by electrochemical deposition of polypyrrole on carbon paper followed by heat treatment. The obtained 9% Co-MoS2/NCFCP hybrid catalyst exhibits an excellent electrocatalytic HER activity with a low overpotential of 174 mV at 10 mA cm−2, a small Tafel slope of 52 mV dec−1 and long-term stability. Thus, Co-MoS2/NCFCP hybrid holds high potential as an efficient earth-abundant electrocatalyst material for HER.

Ultrasound Assisted Electrochemical Deposition of Polypyrrole - Carbon Nanotube Composite Film: Preparation, Characterization and Application to the Determination of Droxidopa

Background: Nowadays, polymeric composites modified with carbonaceous nanomaterials have been popular due to their greater application potentials in many application fields. However, the structural consistency of the composite prepared by electropolymerization suffers from agglomeration of Carbon Nanotubes (CNTs) probably due to their poor dispersion in the coating solution. Present study describes a new synthesis route for the preparation of polypyrrole/CNT composite film on a Glassy Carbon Electrode (GCE) via combining the ultrasonication and electrochemical pulsed deposition for the first time. The performance of the composite film was tested by monitoring the electrochemical oxidation of droxidopa which is used as a new psychoactive drug and synthetic amino acid precursor which acts as a prodrug to the neurotransmitters. Methods: The polypyrrole/CNT composite film was deposited onto a glassy carbon electrode via combining the ultrasonication and electrochemical pulsed deposition. The composite film was characterized by Scanning Electron Microscopy (SEM), Fourier Transfer Infrared Spectroscopy (FTIR), Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV). Then after, the electrochemical behavior of droxidopa was investigated on the GCE/PPy-CNT electrode. Results: SEM images of the surface morphology have revealed a more ordered film formation and enhanced conductivity of the surface has been confirmed by EIS measurements. The synergetic effect of this composite film was tested by monitoring the electrochemical oxidation of a new psychoactive drug; droxidopa at 0.45 V. The influence of solution parameters such as medium pH, pyrrole concentration and amount of CNT along with the instrumental parameters including applied pulse number on the peak formation was investigated by aid of cyclic voltammetry. Under the optimal conditions, by monitoring the oxidation peak in dp mode, two linear ranges have been observed in 4 - 20 μM which is well suited for droxidopa analysis in pharmaceutical preparations. The limit of detection (S/N=3) was calculated as 1.3 μM. Conclusion: Present study offers a fast, easy and sensitive method for the determination of droxidopa by providing a novel route for the preparation of PPy-CNT composite films for any further studies.

Immobilization of phosphotungstate through doping in polypyrrole for supercapacitors.

Immobilization of phosphotungstate is achieved through doping in polypyrrole via the electrochemical deposition of polypyrrole (PPy) in the presence of the phosphotungstate anions (PW12) on carbon nanotube film. Electrochemical stability in neutral solution is realized for PW12 in the prepared ECNT-PPy/5PW12, owing to the proton sponge provided by PPy. ECNT-PPy/5PW12 shows a high areal capacitance of 1300.0 mF cm-2 in LiCl solution at 1 mA cm-2. ECNT-PPy/5PW12 also displays high rate capability and good cyclic stability due to the interaction of incorporated PW12 and the polymer matrix. ECNT-PPy/5PW12 can retain 78.6% and 92.0% of its capacitance with 40-fold current increase and after 10 000 galvanostatic charge/discharge cycles, respectively. An asymmetric supercapacitor with the ECNT-PPy/5PW12 anode and CNT-MnO2 cathode demonstrates high volumetric energy density (4.71 mW h cm-3 at 13.85 mW cm-3) and long cycle life (90.0% capacitance retention after 10 000 charge/discharge cycles).

Material Deposition into Porous Silicon Template

A wide range of materials can be prepared using porous silicon template. The shape and pore size of the starting silicon template, along with the type of material and deposition conditions determine the final synthesized structures. In this work, chemical and electrochemical deposition of various metals and conducting polymers into porous silicon templates are demonstrated, with an emphasis on the processing issues associated with the deposition approach. The electrochemical deposition of polypyrrole into porous silicon template as a case study is addressed and thoroughly discussed.

Super-high rate stretchable polypyrrole-based supercapacitors with excellent cycling stability

The performance and cycling stability of stretchable energy storage devices, such as supercapacitors and batteries, are limited by the structural breakdown arising from the stretch imposed and large volumetric swelling/shrinking. This work demonstrates a very facile and low-cost approach to fabricate stretchable supercapacitors with high performance and excellent cycling stability by electrochemical deposition of polypyrrole (PPy) on smartly-tailored stretchable stainless steel meshes. The fabricated solid-state supercapacitors possess a capacitance up to 170F/g at a specific current of 0.5A/g and it can be effectively enhanced to 214F/g with a 20% strain. Moreover, they can be operated at a very high scan rate up to 10V/s, which are 1–2 orders of magnitude higher than most rates for the PPy electrodes measured even in aqueous electrolytes. Even significantly, the fabricated solid-state supercapacitors under 0% and 20% strains achieve remarkable capacitance retentions of 98% and 87% at a very high specific current of 10A/g after 10,000 cycles, respectively, which are the best for PPy-based solid-state flexible supercapacitors, to the best of our knowledge. The key factors and mechanisms to achieve such high performance are discussed. This facile and low-cost approach developed for fabricating stable and stretchable supercapacitors with high performances could pave the way for next-generation stretchable electronics.

Development of supercapacitor active composites by electrochemical deposition of polypyrrole on carbon nanofibres

In this study, pyrrole monomer is polymerized on carbon nanofibres (CNFs) via electropolymerization. This is a new technique to produce a chemically bonded CNF–polypyrrole composite. Deposition of the polypyrrole (PPy) on the nanofibres was optimized by varying the degree of deposition and deposition speed. Optimization studies have proven that the high deposition amounts result in blocks of polymers, which can be overcome through tuning the degree of polymerization by means number of cycles of electropolymerization and the scan rate of the electropolymerization.

Electrodeposition of a highly adherent and thermally stable polypyrrole coating on steel from aqueous polyphosphate solution

Electrochemical deposition of polypyrrole (PPy) on steel surface has been carried out from an aqueous polyphosphate medium using constant potential coulometry (CPC) and cyclic voltammeter (CV), and the adherence, anticorrosion property and thermal stability of the coated material have been studied. Open circuit potential (OCP) measurements were carried out in a 3.5% NaCl solution. The high OCPs maintained for a period of 40 days suggest that polyphosphate-doped PPy (PPy/PP) retains its oxidative state and provide good corrosion protection for SS-304. It seems that, the large polyphosphate counter-ion prevents the ingress of chloride ions much better than other dopants reported elsewhere. The amount of polypyrrole formed on the steel surface increased with electrodeposition time, monomer concentration and applied potential. However, the effect of potential was higher than the effects of either monomer concentration or deposition time. Also, the effect of electrolyte concentration on the polymer formation was insignificant. Scanning electron microscopy (SEM), however, showed that PPy surface morphology was affected by polyphosphate concentration. Very smooth, compact and adherent PPy films with significantly smaller globules were obtained from solutions with high concentration of polyphosphate. Thermogravimetric analysis of the coated material indicated that PPy/PP has excellent thermal stability at temperatures up to 700 °C, much higher than other conductive polymer coatings cited.

Ultrathin polypyrrole films on silicon substrates

The electrochemical deposition of polypyrrole (PPy) on p-Si(1 0 0) electrodes was investigated. The electrodeposition was performed in aqueous electrolyte solutions utilising cyclic voltammetry. Thin, adhesive, uniform PPy films were successfully deposited on p-Si(1 0 0) electrodes. The Si/PPy interface was characterised with infrared spectroscopic ellipsometry (IR-SE) and photoluminescence (PL) measurements to obtain information of a possible oxidation of the Si interface and charge carrier recombination at the interface, respectively. Very small amounts of interfacial silicon oxides have been found at the Si/PPy interface. PL measurements lead to the assumption that electrodeposition of PPy onto the Si electrodes generated only very few additional non-radiative recombination-active (nr) defects. Hence, polypyrrole is an excellent passivation of nr defects at the silicon surface.

Corrosion study of PVD coatings and conductive polymer deposited on mild steel: Part I: Polypyrrole

Electrochemical deposition of polypyrrole on mild steel substrate was carried out by cyclic voltammetry and galvanostatic technique from neutral aqueous sodium tartrate medium. Homogenous polypyrrole layer for further studies was achieved by galvanostatic technique at constant current density of 5 mA/cm 2. TiN, CrN and diamond-like carbon (DLC) coatings deposited by physical vapor deposition (PVD) technique on mild steel were used for comparison of corrosion properties with polypyrrole film. Electrochemical synthesis of polypyrrole was also applied as a solution for the PVD coatings porosity problem. Polypyrrole film was successfully deposited on all studied PVD coatings by the galvanostatic technique under special conditions. The protection against corrosion was studied by several methods — measurement of potentiodynamic polarization curves, Tafel plot analysis and electrochemical impedance spectroscopy in 3% NaCl solution.

Formation of stable passive film on stainless steel by electrochemical deposition of polypyrrole

Stable passive film has been formed on 304 stainless steel during the electrochemical deposition of polypyrrole (PPy) from sulfuric acid solution. The stability of passive film under PPy increases with aging in H 2SO 4 and this film has much higher resistance to pitting than that formed by anodic polarization under the same condition of aging. XPS studies indicate that the content of chromium components in the oxides under PPy layer is about twice that of the anodically formed passive film with larger value of the ratio Cr 2O 3/Cr(OH) 3. Higher content of iron with a ratio of Fe 2+/Fe 3+ more than unity is also observed with a considerable lower hydration and sulfate content in the oxides under PPy layer. It is suggested that sulfate ion is consumed as a dopant in the formation of PPy film and the oxidation of stainless steel is achieved under the environment of lower concentration of water and sulfate molecules. This may result in the enhancement of formation of corrosion-resisting oxides rather than hydroxides and sulfates.

자기 집합 단분자막 개질 금 전극을 이용한 수용액 중 폴리피를 성장에 관한 In-situ EQCM 연구

Self-assembled monolayer(SAM)로 변형된 금 전극 위로 폴리피롤의 전기화학적 석출 과정을 수용액 상태에서 in-situ EQCM (Electrochemical Quartz Crystal Microbalance)과 ex-situ AFM (Atomic Force Microscopy)을 이용하여 조사하였다. 금 전극에서 cyclic voltammetry로 살펴본 폴리머의 석출은 산화 제한 전위 (anodic limiting potential) 값에 매우 의존적이었으며 주사 횟수에는 의존하지 않았다. 제한 산화 전위가 0.8V (vs Ag | ArCl) 이상일 때 폴리머의 석출은 크게 증가하였다. 그리고 주사 횟수가 증가하면서 질량의 비이상적 변화가 관찰되었는데 이것은 폴리피롤 필름의 rearrangement가 원인이라고 생각된다. 1-dodecanethiol SAM 전극과 thiophene SAM전극에서는 폴리머가 3차원적으로 성장하며 필름의 rearrangement를 수반하였지만 BPUS <TEX>$(Bis(\omega(N-pyrrolyl)-n-undecyl)disulfide)$</TEX> SAM 전극에서는 2차원적인 layer-by-layer 성장을 하고 필름의 rearrangement는 관찰되지 않았다. 폴리머가 급격하게 전극 면으로 석출되면 사슬 모양과 도너츠 모양의 폴리머를 만들며, 정류 상태에 이르면서 주름잡힌 폴리머 필름이 생성되는 것이 원자 힘 현미경 (Atomic Force Microscopy) 이미지로 관찰되었다. The growth of Polypyrrole film has been investigated during electropolymerization in an aqueous solution on bare and SAM modified gold electrodes by in-situ EQCM and ex-situ AFM. According to the result of cyclic voltammetry measurements, in the case of a bare gold electrode, the electrochemical deposition of polypyrrole were dependent on the limiting oxidative potential, but not on scan numbers. When the limiting potential higher than 0.8 V was applied on the electrode, the amount of polypyrrole deposited on a gold electrode was rapidly increased and the abnormal mass change attributed to the rearrangement of polypyrrole films was observed as the scan number increased. The polypyrrole film Prepared on electrodes modified with 1-dodecanethiol SAM or thiophene SAM grew 3-dimensionally with the rearrangement of film. However, in the case of BPUS SAM, 2-dimensional layer-by-layer growth of film was observed without the rearrangement of film. AFM images showed films with chain-shaped and/ or donut-shaped polymers when grown rapidly and a wrinkled film at the steady state condition.

Electrochemical synthesis of polypyrrole/polyimide conducting composite using a polyamic acid precursor

Conducting polymer/poly(amic acid) composites were synthesized by casting poly(amic acid) (PAAc)film onto the surface of stainless steel followed by electrochemical deposition of polypyrrole. Polypyrrole/polyimide (PPy/PI) composites were also formed by preimidizing the polyamic acid film prior to electrodeposition of PPy. The electrical resistance of the bottom side of PPy/PAAc composite (2.3 Ω cm) was lower than that of the PPy/PI composite (6.4 Ω cm), the thickness of the matrix was the same. A PI matrix was used for electropolymerization of pyrrole. The electrodeposition was investigated by using different current densities. IR spectroscopy revealed interactions between the PAAc and PPy in the composite.

Electrochemical synthesis of polypyrrole/carbon nanotube nanoscale composites using well-aligned carbon nanotube arrays

Polypyrrole/carbon nanotube nanoscale composites were successfully fabricated by electrochemical deposition of polypyrrole over each of the carbon nanotubes in well-aligned large arrays. The thickness of the polypyrrole coating can be easily controlled by the value of the film-formation charge. For both thin (low film-formation charge) and thick (high film-formation charge) films, the polypyrrole coating on the surface of each nanotube is very uniform throughout the entire length, as observed by transmission electron microscopy.

Electrochemical deposition of polypyrrole on patterned self-assembled monolayers

Patterned self-assembled monolayers have been fabricated by the reductive desorption of mercaptoacetic acid in mixed monolayers of mercaptoacetic acid and C16SH in alkaline solution. The greater the content of C16SH in the monolayers, the more negative is the reductive desorption potential of mercaptoacetic acid, indicating that mercaptoacetic acid and C16SH did not form patched domains, but mixed well with each other. The electrochemical deposition of pyrrole has been investigated at the patterned monolayers by cyclic voltammetry and atomic force microscopy (AFM). The results show that the polymer film growth strongly depends on the integrity of such patterned monolayers. In the case of patterned monolayers of high integrity, the polypyrrole grows on the top of the monolayers. However, in the case of a large number of pinhole defects, the polymerization results in the formation of polymer nuclei on pinhole sites scattered in the insulating monolayer matrix. The nuclei act as conducting paths to make the redox of the electroactive species more facile.

LIGA-electrodes in voltammetric and spectroelectrochemical studies.

The advantages of lithographic-galvanic (LIGA) fabricated microstructured honeycomb electrodes are demonstrated for spectroelectrochemical cells with respect to the response time (the time necessary to generate the product in a sufficient layer thickness close to the electrode to be detectable by UV-Vis-NIR spectroscopy) and to the conversion of the redox system in solution under thin-layer conditions. Transmission UV-Vis-NIR spectroscopy for several electrochemical applications can be performed in a special spectroelectrochemical cell based on the LIGA electrode and the two quartz rods, forming the walls of the cell and conducting the light beam through the cell. They are limiting the diffusion layer at the structured part of the working LIGA electrode. These microstructured LIGA-electrodes can be used as well defined models of porous electrodes at which redox processes occur under finite diffusion conditions. Such electrodes have been successfully used in the voltammetric and spectroelectrochemical study of various redox systems in both aqueous and non-aqueous solvents. The possibility to fabricate the well defined microstructures from various organic conducting polymers is demonstrated by the electrochemical deposition of polypyrrole in moulded LIGA-forms at high current densities in aqueous solutions.

TiO2/polypyrrole diodes prepared by electrochemical deposition of polypyrrole on microporous TiO2 film

Polypyrrole (PPy) as the material filled in micropores of titanium dioxide (TiO2) was prepared by the electrochemical method. We report morphologies of PPy films with different thicknesses on the microporous films of TiO2 and the influence of the thickness of PPy films on the characteristics of TiO2/PPy diodes. Evidence indicates that a suitable thickness for PPy films is of great importance in enhancing the rectifying ratio (RR) of TiO2/PPy diode.

Thiol-Modified Pyrrole Monomers: 4. Electrochemical Deposition of Polypyrrole over 1-(2-Thioethyl)pyrrole

The electrochemical deposition of polypyrrole (PPy) potentiodynamically and potentiostatically over monolayers of 1-(2-thioethyl)pyrrole (1-TEP) is described. The relationship between monolayer oxidation and PPy growth depended strongly on the electrolyte. In propylene carbonate/LiClO4, the PPy polymerization potential was higher than that for 1-TEP monolayer oxidation, and the monolayer oxidation peak was identical to that seen in monomer-free electrolyte. In water/LiClO4, the oxidation and polymerization potentials were almost the same, with the result that the onset of polymerization was prevented until after the monolayer oxidation process had been completed. In water/(sodium dodecylbenzenesulfonate), an anionic surfactant, the PPy polymerization potential was lower than that in water/LiClO4, and polymerization apparently occurred without monolayer oxidation. In all cases, PPy growth was found to be essentially the same on 1-TEP, oxidized 1-TEP, and clean gold as evidenced by cyclic voltammograms, chr...