Electrochemical Oxidative Polymerization Research Articles

High Voltage, Long Cycling Organic Cathodes Rendered by In Situ Electrochemical Oxidation Polymerization

High Voltage, Long Cycling Organic Cathodes Rendered by In Situ Electrochemical Oxidation Polymerization

Multi-responsive Electropolymer Surface Coatings Based on Azo Molecular Switches and Carbazoles: Light, pH, and Electrochemical Control of Z→E Isomerization in Thin Films.

Light-responsive surfaces are attracting increasing interest, not least because their physicochemical properties can be selectively and temporally controlled by a non-invasive stimulus. Most existing immobilization strategies involve the chemical attachment of light-responsive moieties to the surface, although this approach often suffers from a low surface concentration of active species or a high inhomogeneity of applied coatings. Herein, electropolymerization of carbazoles as a facile and rapid approach for preparing light-responsive azo-based surface coatings is presented. The electrochemical oxidative polymerization of bis-carbazole containing azo-monomers yields stable films, in which the photochemical properties and specific pH sensitivity of azo molecular switches are retained. Moreover, the molecular design enables electrocatalytic control over Z→E azo double bond isomerization facilitated by the conductive polycarbazole backbone. Ultimately, the high degree of control over macromolecular properties yields conductive surface coatings responsive to a range of stimuli, showing great promise as a strategy for versatile application in organic electronics.

Electro-Oxidative Polymerization of Aromatic Monomers without an Electric Power Supply

Electrochemistry is a powerful tool for organic synthesis based on electron transfer-driven reactions at the substrate/electrode interface. The use of electricity for synthetic reactions without the need for hazardous chemical oxidants and reductants is recognized as a green and sustainable approach. We have recently developed a split bipolar electrode (s-BPE) system [1], in which the redox reactions can be driven in a low electrolyte concentration, with batch [2,3] and flow [4] cells. Herein, we report a novel s-BPE system for organic electrosynthesis driven under a streaming potential condition with a pressure flow. As a proof-of-concept study on electrosynthesis without an electric power supply, electrochemical oxidative polymerization of aromatic monomers such as pyrrole successfully yielded the corresponding polymer films on an electrode surface at the upstream, which acted as an anode [5].[1] Shida, N.; Zhou, Y.; Inagi, S. Chem. Res. 2019, 52, 2598-2608.[2] Miyamoto, K.; Nishiyama, H.; Tomita, I.; Inagi, S. ChemElectroChem 2019, 6, 97-100.[3] Shida, N.; Villani, E.; Sanuki, M.; Miyamoto, K.; Gotou, A.; Isogai, I.; Yamauchi, A.; Fuchigami, T.; Tomita, I.; Inagi, S. Electrochemistry, 2021, 89, 476-479.[4] Sakagami, H.; Takenaka, H.; Iwai, S.; Shida, N.; Villani, E.; Gotou, A.; Isogai, T.; Yamauchi, A.; Kishikawa, Y.; Fuchigami, T.; Tomita, I.; Inagi, S. ChemElectroChem, 2022, 9, e202200084[5] Iwai, S.; Suzuki, T.; Sakagami, H. Miyamoto, K.; Chen, Z.; Konishi, M.; Villani, E.; Shida, N.; Tomita, I.; Inagi, S. Commun. Chem., 2022, 5, 66.

New construction of polypyrrole interphase layers to improve performance stability of NaTi2(PO4)3 anode for aqueous Na-ion batteries

NaTi2(PO4)3 (NTP) as a promising anode material for aqueous sodium-ion batteries has attracted widespread attention. However, the NTP material commonly exhibits significant capacity fade, possibly mainly attributing to the change of the chemical stability of NTP in the aqueous electrolytes. Coating NTP with polypyrrole (PPY) conductive polymers is a promising strategy to solve this problem, but in situ synthesis of the PPY polymer in the presence of the NTP active materials seems not to be easy, reported by the previous work, owing to the inferior adhesion of the synthesized PPY to the NTP surface. Thereby, this work has attempted ex situ synthesis of PPY coatings on the carbon-coated NTP (NTP/C) anode surface in the presence of small amounts of carbon conductive additives and organic binders, and then it shows that synthesized conductive PPY interphase layer can readily adhere to the NTP surface with no visible phase separation through the electrochemical oxidation polymerization under certain potentials in the pyrrole (PY)-containing electrolytes. The corresponding optimized oxidation modification conditions of the anode can be obtained, and the evolution law of the anode interface with the content of the electrolyte additives, the oxidation potential and the oxidation time can be established. Thus, the as-synthesized optimal modified anodes, with the thickness of about 24 μm for the PPY coating, are observed to have fairly large charge/discharge capacity of 228.6 mAh·g−1, high coulombic efficiency (> 95%) and enhanced cycling stability. Furthermore, a schematic for the charge/discharge processes involving possible reaction pathways at the modified anodes with the PPY layers in Na2SO4 aqueous electrolytes has been proposed.

In Situ Constructing a Catalytic Shell for Sulfur Cathode via Electrochemical Oxidative Polymerization.

Sluggish multiphase reaction kinetics and severe shuttle effect of lithium polysulfides (LiPSs) are two major challenges facing lithium-sulfur (Li-S) batteries, which largely prevent them from becoming a reality. Herein, a shell with catalytic function for sulfur cathode is in situ constructed through an ingenious electrochemical oxidative polymerization strategy by introducing hexafluorocyclotriphosphazene (HFPN) as additives, which suppresses the shuttle effect and promotes efficient sulfur conversion. The shell with abundant heteroatoms effectively confines polysulfides to the cathode matrix by chemically interacting with them to eliminate capacity degradation. Moreover, the shell exhibits high catalytic activities, which turns Li2S(2) into an activated state and facilitates its dissociation. The functionalized shell substantially advances the performance of Li-S batteries, thanks to efficient lithium-ion transportation and abundant adsorption-catalytic sites. As a result, Li-S batteries demonstrate superb resistance to self-discharge, ultrastable cycle performance, and greatly enhanced rate capability. Impressively, the batteries show an ultralow capacity decay rate of 0.034% throughout 700 cycles at 2C. They deliver a capacity of 517 mAh g-1 even at a 4C rate, exhibiting relieved electrochemical polarization and excellent sulfur utilization. This work provides an ingenious strategy to construct adsorption-catalytic nets for next-generation Li-S batteries with enhanced lifespan and electrochemical performance.

Electrically Copolymerized Polydopamine Melanin/Poly(3,4-ethylenedioxythiophene) Applied for Bioactive Multimodal Neural Interfaces with Induced Pluripotent Stem Cell-Derived Neurons.

Multimodal neural interfaces include combined functions of electrical neuromodulation and synchronic monitoring of neurochemical and physiological signals in one device. The remarkable biocompatibility and electrochemical performance of polystyrene sulfonate-doped poly(3,4-ethylenedioxythiophene) (PEDOT:PSS) have made it the most recommended conductive polymer neural electrode material. However, PEDOT:PSS formed by electrochemical deposition, called PEDOT/PSS, often need multiple doping to improve structural instability in moisture, resolve the difficulties of functionalization, and overcome the poor cellular affinity. In this work, inspired by the catechol-derived adhesion and semiconductive properties of polydopamine melanin (PDAM), we used electrochemical oxidation polymerization to develop PDAM-doped PEDOT (PEDOT/PDAM) as a bioactive multimodal neural interface that permits robust electrochemical performance, structural stability, analyte-trapping capacity, and neural stem cell affinity. The use of potentiodynamic scans resolved the problem of copolymerizing 3,4-ethylenedioxythiophene (EDOT) and dopamine (DA), enabling the formation of PEDOT/PDAM self-assembled nanodomains with an ideal doping state associated with remarkable current storage and charge transfer capacity. Owing to the richness of hydrogen bond donors/acceptors provided by the hydroxyl groups of PDAM, PEDOT/PDAM presented better electrochemical and mechanical stability than PEDOT/PSS. It has also enabled high sensitivity and selectivity in the electrochemical detection of DA. Different from PEDOT/PSS, which inhibited the survival of human induced pluripotent stem cell-derived neural progenitor cells, PEDOT/PDAM maintained cell proliferation and even promoted cell differentiation into neuronal networks. Finally, PEDOT/PDAM was modified on a commercialized microelectrode array system, which resulted in the reduction of impedance by more than one order of magnitude; this significantly improved the resolution and reduced the noise of neuronal signal recording. With these advantages, PEDOT/PDAM is anticipated to be an efficient bioactive multimodal neural electrode material with potential application to brain-machine interfaces.

Removal of malachite green by electrochemical oxidation polymerization and electrochemical reduction precipitation: its kinetics and intermediates

Removal of malachite green by electrochemical oxidation polymerization and electrochemical reduction precipitation: its kinetics and intermediates

Asymmetric Activation of the Nitro Group over a Ag/Graphene Heterointerface to Boost Highly Selective Electrocatalytic Reduction of Nitrobenzene

The electrocatalytic reduction of nitrobenzene to aniline normally faces high overpotential and poor selectivity because of its six-electron redox nature. Herein, a Ag nanoparticles/laser-induced-graphene (LIG) heterointerface was fabricated on polyimide films and employed as an electrode material for an efficient nitrobenzene reduction reaction (NBRR) via a one-step laser direct writing technology. The first-principles calculations reveal that Ag/LIG shows the lowest activation barriers for the NBRR, which could be attributed to the optimum adsorption of the H atom realized by the appropriate interaction between Ag/LIG heterointerfaces and nitrobenzene. As a result, the overpotential of the NBRR is reduced by 217 mV after silver loading, and Ag/LIG shows a high aniline selectivity of 93%. Furthermore, an electrochemical reduction of nitrobenzene in tandem with an electrochemical oxidative polymerization of aniline was designed to serve as an alternative method to remove nitrobenzene from the aqueous solution. This strategy highlights the significance of heterointerfaces for efficient electrocatalysts, which may stimulate the development of novel electrocatalysts to boost the electrocatalytic activity.

Electropolymerization without an electric power supply

Electrifying synthesis is now a common slogan among synthetic chemists. In addition to the conventional two- or three-electrode systems that use batch-type cells, recent progress in organic electrochemical processes has been significant, including microflow electrochemical reactors, Li-ion battery-like technology, and bipolar electrochemistry. Herein we demonstrate an advanced electrosynthesis method without the application of electric power based on the concept of streaming potential-driven bipolar electrochemistry. As a proof-of-concept study, the electrochemical oxidative polymerization of aromatic monomers successfully yielded the corresponding polymer films on an electrode surface, which acted as an anode under the flow of electrolyte in a microchannel without an electric power supply.

Preparation and performance of polyaniline modified coal-based carbon membrane for electrochemical filtration treatment of organic wastewater

Electrochemical filtration process, in which the active conductive membranes were employed as filtration membrane and electrochemical active electrode simultaneously, exhibited great prospect on the organic wastewater treatment. In this work, an efficient metal-free polyaniline-coated coal-based carbon membrane (PANI/CM) was fabricated via a facile electrochemical polymerization deposition method. Structural properties and electrochemical properties of PANI/CM were systematically characterized via SEM, XRD, FTIR, XPS and electrochemical workstation, etc. The electrochemical filtration treatment performance of PANI/CM for organic wastewater was systematically investigated. Results showed that the PANI was successfully deposited on the coal-based carbon membrane (CM) through electrochemical oxidative polymerization deposition method. The PANI coating can effectively improve the hydrophilicity of CM. Under the optimal preparation condition, the PANI/CM achieved a high permeability of 2564.67 L·m−2·h−1·bar−1 (1410.57 L·m−2·h−1·bar−1 for CM). In addition, PANI/CM possessed higher electrochemical activity and stability than CM, and the phenol and COD removal efficiencies of PANI/CM were up to >99.32% and 84.85%, respectively, under the operation condition of 2.0 V applied voltage, 50 mg·L-1 phenol, 2.5 g·L-1 Na2SO4 and 2.0 ml·min−1 flow rate, which were much higher than that of CM (70.12% and 63.64%, respectively). Additionally, the electrochemical oxidation mechanism of PANI/CM during the electrochemical filtration was explored, which included both indirect oxidation and direct oxidation. Furthermore, it was verified that PANI/CM also exhibited excellent applicability for different types of organic pollutants and the long-term stability.

Investigation of Some Ion Selective and Water Repellent Properties of Carbazole Based Polymers

A polymer derived from poly-9-bis[4-(thiophen-3,4-yloxy)biphenyl)]-9H-carbazole containing a carbazole and thiophene group, abbreviated as B2, was synthesized via the oxidation method by using FeCl3 as an oxidant. Additionally, P(B2) was synthesized and coated onto an ITO–glass surface via electrochemical oxidative polymerization. UV spectra of these polymers and their metal complexes (like Fe2+, Cd2+, Hg2+, Pb2+) were recorded in DMSO solutions, and then their UV spectra depending on the concentration were recorded. According to the results, when the concentration was rising, the absorbance peak intensity increased gradually for B2. Also, for P(B2), the absorbance peak followed a fluctuating course. The photo images of its some metal complexes were recorded under UV light. Resultantly, B2 polymer was determined to be selective against Fe2+ ion and it can be said that B2 could be used as fluorescence Fe2+ ion probe. Finally, contact angle (CA) measurements of B2 and P(B2) were realized and, according to the recorded photo images it can be said that B2 had more hydrophobic property than P(B2).

SnO2 and Ni doped SnO2 /polythiophene nanocomposites for gas sensing applications

This short letter reports the achievement of promising sensing properties by using pure and Ni doped SnO2-Polythiophene nanostructured materials. These nanocomposites of SnO2 (undoped and doped with Ni) and polythiophene (PTh) were synthesized by electrochemical oxidative polymerization of thiophene in the presence of the two types of nanoparticles obtained by co‐precipitation. The as obtained materials were used as active layer in sensing devices. The nanocomposites were structurally characterized and their electrochemical properties were evaluated by cyclic voltammetry. The nanocomposites conductivity variation with temperature was studied in air and then were exposed to different pollutant gases to investigate the composites suitability for gas sensing applications, which prove to be promising materials.

Carbon dots with pH-responsive fluorescence: a review on synthesis and cell biological applications.

This review summarizes state of the art synthesis and applications of carbon dots (CDs) with pH-responsive fluorescence. Following an introduction, the first section covers methods for the preparation of pH-responsive CDs, with subsections on general methods for preparing CDs (by hydrothermal, solvothermal, electrochemical, microwave, laser ablation, pyrolysis or chemical oxidation polymerization methods), and on precursors for synthesis. This is followed by a section on the mechanisms of pH-responsivity (by creating new functional groups, change of energy levels, protonation and deprotonation, aggregation, or by introduction shells). Several Tables are presented that give an overview of the wealth of methods and materials. A final section covers applications of carbon dots (CDs) with pH-responsive fluorescence for sensing, drug delivery, and imaging. The conclusion summarizes the current status, addresses challenges, and gives an outlook on potential future trends. Graphical abstract The synthesis and biological applications of carbon dots(CDs) with pH-responsive fluorescence are summarized. Precursors and methods for preparation of pH-responsive CDs, mechanisms of pH-responsivity, and biological applications of CDs with pH-responsive fluorescence for sensing, drug delivery, and imaging are discussed.

Tuning electrical properties of polythiophene/nickel nanocomposites via fabrication

Polythiophene/nickel nanocomposites were synthesized by the electrochemical oxidative polymerization of thiophene in the presence of nickel nanoparticles. The nanocomposites were characterized by scanning electron microscopy, energy dispersive X-ray analysis, atomic force microscopy and Raman spectroscopy. It was found that both PTh and PTh/Ni nanocomposites show granular structures with grains that agglomerate. The increasing of the Ni content results in a decreasing in size and an increasing in density of insular PTh/Ni agglomerations. All composite samples present smaller grains and agglomerations as compared to pure PTh. As the Ni content increases both Ra and RMS are slightly increasing. Surface area was also estimated and the results showed a slightly increase of active surface area. Their electrochemical properties were further evaluated utilizing cyclic voltammetry. As-grown nanocomposites of PTh/nickel with the highest content of nickel exhibited enhanced electrochemical activity, the highest specific capacitance of 3000 F g−1 and the fastest discharging process of 200 s.

Simultaneous electro-synthesis of polyaniline graphene nanocomposite in dilute graphene oxide as dopant and aniline by electrochemical method and its high specific capacitance

A composite of reduced Graphene oxide -polyaniline (RGO-PANI) was fabricated by an in situ electrochemical oxidative polymerization of aniline in the presence of GO in Sodium dodecyl sulfate (SDS), which synthsized by anodic exfoliation, on carbon paper electrode. Here GO uses as a protonation agent for doping of PANI and also as a physical crosslinker of PANI fibers. The structure and the property of RGO-PANI composite were investigated by tunneling electron microscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, cyclic voltammetry, galvanostatic charge–discharge test and electrochemical impedance spectroscopy (EIS) techniques. The fabricated composite was then employed as the supercapacitor, which provides specific capacitances as high as 890 F g−1 at the current density of 1 A g−1 in 1 M H2SO4 aqueous solution. Long term stability and high specific capacitance, are related to synergistic effects between PANI and RGO and also conductive graphene sheets. EIS indicates a decreasing charge transfer resistance at the electrode/electrolyte interface of RGO-PANI composite than each individual component. This work may suggest an alternative method to synthesis one-pot produce of RGO-PANI composite for the development of high-performance supercapacitors.

2,7-Linked N-methylcarbazole copolymers by combining the macromonomer approach and the oxidative electrochemical polymerization

The preparation of copolymers bearing N-methylcarbazole and 2,7-linked 3,4-ethylenedioxythiophene units has been carried out using the N-methyl-2,7-di(2-(3,4-ethylenedioxythienyl))carbazole monomer, which has been chemically synthesized through the Stille coupling reaction of 2,7-dibromo-N-methylcarbazole and tributyl-stannylated 3,4-ethylenedioxythiophene. Then, the monomer was electropolymerized by chronoamperometry in acetonitrile with 0.1 M LiClO4 under a constant potential of 0.70 V and using steel AISI 316 electrodes. The electrochemical activity and stability, charge–discharge capacity, charge transfer resistance and surface properties (i.e. morphology, topography and wettability) of the resulting polymer have been characterized and compared with those reported for poly(3,4-ethylenedioxythiophene). Finally, the polymer has been obtained by potentiodynamic sweep, applying around 100 cyclic voltammetry steps to an acetonitrile solution of the N-methyl-2,7-di(2-(3,4-ethylenedioxythienyl))carbazole monomer with 0.1 M LiClO4. Results show that although this technique has been mostly used to electropolymerize diheteroaromatic-subtituted carbazoles, the resulting material presents serious disadvantages with respect to that produced by chronoamperometry under a constant potential.

D.C electrical conductivity of prepared pure and doped polyaniline salt

Pure Polyaniline salt, and protonation PANI by H2SO4 were synthesized by electro-chemical oxidative polymerization of aniline with acidity of H2SO4. The solution was prepared in reaction temperature equal 291 K and the acidity of aqueous solution was 1 molarities. The prepared polyaniline was characterized by FT-IR, the result indicate that the intensity is increase with increasing of applied voltage. The dc conductivity has been measured for bulk polyaniline pure and doped in the form of compressed pellet with evaporated Ohmic Al electrodes in temperature range (303-423) K. The Eav energy of the thermal rate process of the electrical conductivity was determined. The results indicate that the dc conductivity of doped samples are two or three orders of magnitude higher by comparison with the pure sample and found that the increasing in conductivity of prepared samples with applied voltage is systematic.

Molecular frameworks of polymerized 3‑aminobenzoic acid for chemical modification and electrochemical recognition

The main purpose of this work is to provide insight into the molecular frameworks that are the products of 3‑aminobenzoic acid (3ABA) polymerization. The employment of vibrational spectroscopic (FTIR and FT-Raman) and mass spectrometric (MS) methods enabled us to determine the structures of oligomers that form during both the chemical and electrochemical oxidative polymerization of 3ABA. It was found that i) the intermolecular connections in the nanolayer were realized through amino groups similarly to the aniline polymerization mechanism, ii) the carboxyl groups of 3ABA were not significantly damaged during polymerization, which was important for their subsequent post-modification by 3‑aminophenylboronic acid (3APBA); iii) the presence of both amino and phenolic groups on oligomeric backbones was responsible for appropriate acid-base behaviour and also for the N‑acetylneuraminic acid (NANA) recognition that occurred between the modified electrode surface and the tested solutions, in which both pH and NANA content varied. The pH sensitivity of oligomers deposited onto a platinum disc electrode observed during potentiometric measurements additionally confirmed the presence of groups (in particularly, carboxyl and amino groups) taking part in acid-base equilibrium and contributing to the recognition process. The ability of modified oligomers to detect NANA was proved using electrochemical impedance spectroscopy (EIS) and potentiometry in the range from 25μM up to 741μM NANA at pH7, independently of the measuring technique.

Synthesis and Redox Behavior of a Sheathed Cross-Conjugated Polythiophene

Control over the electronic structure in π-conjugated polymers is of great importance for the development of organic electronics and spintronics. In this study, we synthesized a sheathed cross-conjugated polythiophene through oxidative electrochemical polymerization. Spectroelectrochemistry has revealed that unlike linearly conjugated polythiophenes, polarons were confined in the repeating units that were segmented by cross-conjugation.

Electrochemical polymerization of triphenylamine end-capped dendron: Electrochromic and electrofluorochromic switching behaviors

Triphenylamine unit containing two electroactive end-capped dendritic macromolecules Benz-3TPA and Benz-3CNTPA have been rationally designed and successfully synthesized with good yield. Their structures contain benzene moieties as part of the core. Both dendrons have formed the polymers (p-Benz-3TPA and p-Benz-3CNTPA) through the oxidative electrochemical polymerization and also are capable of showing simultaneous operation in electrochromic (EC) and electrofluorochromic (EFC) properties. These two polymer films have exhibited stable reversible multi-color electrochromic changes with high coloration efficiency and contrast ratio upon electro-oxidation. These electrochromic polymers have not only produced EC properties with high optical contrast (ΔT% = 65–71%) but also exhibited high contrast ratio (Ion/Ioff = 179, Ion = fluorescence on (neutral state) and Ioff = fluorescence off (oxidized state)) EFC properties at low working voltage. Both have still showed excellent electro-switching stability even after hundredth cycles. Solid state electrochromic devices (ECD) using both the polymers have been fabricated and its color and fluorescent state are simultaneously switched by an applied potential, making the polymer a unique candidate for electrochemical fluorescence and electrochromic applications in future.