Repetitive Cyclic Voltammetry Research Articles

Electrosynthesis of tunable NiO/CuO-printed circuit board electrodes for glucose sensing

In this research work, a copper-based printed circuit board (Cu-PCB) was used as an electrode substrate. Alloyed copper-nickel oxides were synthesized on the surface of the Cu-PCB electrode by the two stages: In the first step, the electrodeposition of copper-nickel alloy on the surface of the Cu-PCB electrode was carried out by cyclic chronopotentiometric method (8 cycles) at the optimized conditions. In the second step, the Ni/Cu-PCB electrode was immersed in 1 M NaOH electrolyte solution, followed by the electrochemical synthesis of the alloyed copper-nickel oxides by repetitive cyclic voltammetry (40 cycles) and subsequently, the NiO/CuO-PCB electrode was obtained. The surface structure and morphology of NiO/CuO-PCB and Cu-PCB electrodes were comparatively investigated by SEM, EDX, and XRD techniques. Moreover, the electrochemical behavior and electrocatalytic properties of NiO/CuO-PCB electrode have been effectively investigated. To study the electrocatalytic efficiency of the NiO/CuO-PCB electrode, the measurement of glucose as a biological target was studied by cyclic voltammetry (CV) and amperometry approaches as well. The limit of glucose detection (LOD) and sensitivity of the proposed method in glucose assay were calculated as 5.4 and 1.1 µM, and 118.14 and, 112.08 mA/M by CV and amperometry approaches, respectively. Two-segment calibration graphs were found over the range 1.4–120 mM by CV, and 0.14–180 mM by hydrodynamic amperometry techniques. The fabricated sensor was successfully used to measure glucose in blood serum and human plasma samples.

Investigation of the effects of ethanolamine, 2-mercaptoethanol and citrate as capping agent and heteroatom source on ethylene glycol oxidation activity of heteroatom-doped reduced graphene oxide nanocomposites decorated with gold nanoparticles

In this study, ethanolamine and 2-mercaptoethanol were tested for the first time as capping agents and heteroatom sources in the preparation of heteroatom-doped reduced graphene oxides (Au/E@rGO and Au/M@rGO) decorated with Au nanoparticles that can be used as catalysts in ethylene glycol (EG) fuel cells. The performance of the composites was compared with the composite prepared at the same conditions using sodium citrate dihydrate (Au/C@rGO), a widely used capping agent in the literature. The average particle size of Au nanoparticles in Au/E@rGO, Au/M@rGO, and Au/C@rGO were calculated as 10.55 ± (5.10) nm, 5.82 ± (2.35), and 3.36 (±1.02 nm) based on the TEM analysis, respectively. Amounts of Au loaded to Au/E@rGO, Au/M@rGO, and Au/C@rGO were determined as 36.50 (±0.51) %, 39.04 (±1.13) %, and 27.66 (±0.08) %, respectively. The EG oxidation performance of Au/E@rGO was 5 and 14 times higher than that of Au/C@rGO and Au/M@rGO. Chronoamperometry measurements showed that Au/E@rGO, Au/C@rGO, and Au/M@rGO catalysts retained 18.72%, 7.31%, and 4.06% of their initial currents, respectively, revealing that Au/E@rGO maintained its stability significantly compared to Au/C@rGO and Au/M@rGO. Repetitive cyclic voltammetry measurements also verified the high stability of Au/E@rGO in EG oxidation. The results showed that ethanolamine can be used as a potential capping and N-doping agent in the preparation of carbon structures containing Au nanoparticles that can be used in fuel cells.

A refreshing perspective on electrochromic materials: Phenoxazine as an opportune moiety towards stable and efficient electrochromic polyimides

In our attempt to develop appealing EC materials, here we address the electrochromic materials field by employing the aryl-substituted phenoxazine (POZ) as a new member of triarylamine family with excellent potential for electrochromic applications. Thus, a simple synthetic strategy was followed to build a novel POZ-based diamine that was further used in polycondensation reaction with commercially available aromatic dianhydrides to develop three novel polyimides (PIs). Complementarily, POZ-based model compounds were synthesized to get insights into the electrochemical and electrochromic behavior of the synthesized PIs. With the support of the computational quantum mechanical modeling methods (Density-Functional Theory – DFT and Time-Dependent (TD)–DFT), the mechanism responsible for the absence of the dimerization process upon POZ oxidation was established. Without resorting to any structural modification to block the para position of POZ, the present PIs demonstrated exquisite electrochemical and electrochromic performance, including high redox stability during 100 repetitive cyclic voltammetry scans, unique deep-purple coloration during oxidation, high optical contrast, up to 62%, response time below 6.5 s for coloring and 5.1 s for bleaching, excellent electrochromic efficiency, up to 193 cm2/C and a maximum 21% decay of the electrochromic efficiency after 500 cycles. The most efficient EC polyimide was used as an active layer in electrochromic prototype devices to survey the full applicative potential of these PIs. The devices rendered an optical contrast of 51%, 7.9 s for coloring, and 7.2 s for bleaching, electrochromic efficiency of 178 cm2/C, and decay of the electrochromic efficiency of 6.1% after 100 cycles, placing for the first time the POZ-based PIs among the perspective electrochromic materials.

Corrosion protection efficiency of the electrochemically synthesized polypyrrole-azo dye composite coating on stainless steel

The polypyrrole-azo dye (Lanaset-Red-2B) composite coatings were electrochemically deposited on stainless steel 430 by means of repetitive cyclic voltammetry. The composite coatings were synthesized by addition of the dye in 10−6–10−3 M range to 0.1 M oxalic acid solution containing 0.1 M pyrrole monomer. All polypyrrole/Lanaset-Red-2B composite coatings are more protective with respect to the pristine polypyrrole in NaCl (3.5%) medium. The best protective coating synthesized in the presence of 10−5 M dye using optimized potential range, scan-rate and cycle number were characterized by infrared-reflection-absorption-spectroscopy, scanning-electron-microscopy and energy-dispersive-spectroscopy analyses. The electrochemical characterizations were performed by using potentiodynamic polarization and electrochemical-impedance-spectroscopy techniques. The steel coated with the polypyrrole/Lanaset-Red-2B composite is more resistant in 0.1 M H2SO4 solution comparing to NaCl (3.5%) during long-term immersion until 432 h. The corrosion protection efficiency of the coating is higher than that of its initial value at the end of 432 h immersion in both media due to controlled release of the Lanaset-Red-2B deposited as inhibitor in the polypyrrole structure.

Boosting the oxygen evolution reaction performance of wrinkled Mn(OH)2 via conductive activation with a carbon binder

Electrochemical water splitting is one of the most reliable approaches for environmental-friendly hydrogen production. Because of their stability and abundance, Mn-based materials have been studied as electrocatalysts for the oxygen evolution reaction (OER), which is a more sluggish reaction in the water splitting system. To increase the OER activity of Mn, it is imperative to facilitate the structural change of Mn oxide to the active phase with Mn3+ species, known as the active site. Here, we present the relationship between the electronic conductivity in the catalyst layer and the formation of the Mn active phase, δ-MnO2, from wrinkled Mn(OH)2. Mn(OH)2 has poor conductivity, and it disrupts the oxidation reaction toward MnOOH or δ-MnO2. Adjacent conductive carbon to Mn(OH)2 enabled Mn(OH)2 to be oxidized to δ-MnO2. Furthermore, after repetitive cyclic voltammetry activation, the more conductive environment resulted in a higher density of δ-MnO2 through the irreversible phase transition, and thus it contributes to the improvement of the OER activity.

Electrochemical H2 Production using Polypyrazole based Zinc(II) Complex in Alkaline Medium

A zinc(II) complex of polypyazole containing ligand namely, [Tp*ZnCl] (Zn1) {Tp* = tris(3,5-dimethylpyrazolyl)borate}, along with its zinc(II) bound hydroxo complex [Tp*Zn–OH] (Zn2) were synthesized and characterized by FT-IR, Raman, 1H NMR techniques and elemental analysis. In alkaline solution (0.1 M KOH), the Zn2 modified glassy carbon (GC), namely GC–Zn2, was investigated as a molecular electrocatalyst for the hydrogen evolution reaction (HER). Different quantities (ca. 0.1–0.5 mg cm–2) of Zn2 were loaded on GC electrodes to make various GC–Zn2 electrodes. These electrodes were utilized as cathodes in 0.1 M KOH to produce H2 using linear sweep voltammetry (LSV) measurements. The HER electrocatalytic activity of the GC–Zn2 catalyst was found to be quite high and it increased with the catalyst loading density. The top performing electrocatalyst, GC–Zn2 (0.5 mg cm–2), demonstrated considerable HER catalytic performance with a low HER onset potential (EHER) of –33 mV vs. RHE and a high exchange current density of 0.59 mA cm–2. Moreover, the top performing electrocatalyst had a Tafel slope of –152 mV dec–1 and consumed an overpotential of 135 mV to generate a current density of 10 mA cm–2. Under the same operating conditions, these HER electrochemical kinetic parameters were found to be not remarkably far from those determined for commercial Pt/C (–10 mV vs. RHE, 0.88 mA cm–2, 108 mV dec–1 and 110 mV to yield a current density of 10 mA cm–2). In addition, the most active molecular electro-catalysts for H2 production from aqueous alkaline electrolytes were found to be comparable to the HER electrochemical kinetic parameters reported here for the GC–Zn2 electrocatalyst. Using 5000 cycles of repetitive cyclic voltammetry and 48 h of chronoamperometry measurements, the best electrocatalyst’s stability and long term durability were tested. It exhibited high stability for the HER catalytic activity.

Simultaneous electrochemical deposition of nickel cobalt oxide-reduced graphene oxide composites for high performance asymmetric supercapacitors

In this work, a one-step electrodeposition approach was applied for nanosheets fabrication of binder free nickel cobalt oxide (NCO) and NCO-reduced graphene oxide (NCO-rGO) composites on the nickel-foam substrate by repetitive cyclic voltammetry (rCV). The NCO-rGO hybrids were firstly fabricated on Ni foam surface with the reduction of GO and electrodeposition of NCO simultaneously. Interaction of NCO particles with rGO sheets increased the conductivity of the composite and consequently facilitated the electron transfer rate. Electrochemical measurements proved that specific capacitance and cyclic performance of as-prepared materials were improved with the synergistic effect of rGO in the hybrid structure. The optimized NCO-rGO electrode exhibited a specific capacitance of 1916.5 F g−1 at 1 A g−1 with superior stability of 95.6% at a high current density of 10 A g−1 even after 3000 cycles. To explore its practical applications, an asymmetric supercapacitor (ASC) based on NCO-rGO as a positive electrode and rGO as a negative electrode was constructed, which exhibited a prominent specific energy of 45.22 Wh kg−1 at 400 W kg−1. As a result, NCO-rGO hybrid structure as the functional electrode material for the supercapacitors with remarkable electrochemical performance were obtained, thanks to the increased conductivity and decreased mass by removing binders.

Simultaneous electrodeposition of electrochemically reduced graphene oxide-binary metal chalcogenide composites to enhance photoelectrochemical performance

In this study, a facile and one-step simultaneous electrodeposition of the composite thin films bearing binary metal chalcogenides (CdxZn1-xS (x = 0.0, 0.2, 0.5, 0.8, 1.0)) and electrochemically reduced graphene oxide (RGO) was carried out via repetitive cyclic voltammetry (rCV). Then their photoelectrochemical (PEC) performances were investigated under the solar light irradiation to find out the optimized composition of the composites. Immobilization of Cd1-xZnxS nanoparticles among the RGO sheet with the rCV confined the Cd1-xZnxS nanoparticles between the RGO sheets, which prevented leakage of these particles from the electrode surface and contributed to the increase of active sites for the PEC reaction. PEC results showed that increasing x from 0 to 0.8 in CdxZn1-xS composition boosted the photocurrent density, reaching from 25 μA cm−2 to 438 μA cm−2. Incorporation of RGO to the structure increased the conductivity and prevented the photocorrosion of Cd0.8Zn0.2S, thus, RGO(0.25)-Cd0.8Zn0.2S enhanced the photocurrent density from 0.44 mA cm−2 (as-synthesized Cd0.8Zn0.2S) to 1.38 mA cm−2.

Efficient Electrochemical Water Oxidation by a Trinuclear Ru(bda) Macrocycle Immobilized on Multi‐Walled Carbon Nanotube Electrodes

AbstractCatalytic water splitting is a viable process for the generation of renewable fuels. Here it is reported for the first time that a trinuclear supramolecular Ru(bda) (bda: 2,2′‐bipyridine‐6,6′‐dicarboxylate) catalyst, anchored on multi‐walled carbon nanotubes and subsequently immobilized on glassy carbon electrodes, shows outstanding performance in heterogeneous water oxidation. Activation of the catalyst on anodes by repetitive cyclic voltammetry (CV) scans results in a catalytic current density of 186 mA cm−2 at a potential of 1.45 V versus NHE. The activated catalyst performs water oxidation at an onset overpotential of 330 mV. The remarkably high stability of the hybrid anode is demonstrated by X‐ray absorption spectroscopy and electrochemically, revealing the absence of any degradation after 1.8 million turnovers. Foot of the wave analysis of CV data of activated electrodes with different concentrations of catalyst indicates a monomolecular water nucleophilic attack mechanism with an apparent rate constant of TOFmax (turnover frequency) of 3200 s−1.

Nonenzymatic and low potential glucose sensor based on electrodeposited Ru-nanofilm from ionic liquid electrolyte

In this work, the Repetitive cyclic voltammetry method used to electrodeposition of thin Ruthenium film from the ionic liquid (bmimPF6) solution of RuCl3. The FESEM, EDX, XPS, and AFM used to evaluate and characterization of prepared film. The imaging results indicated well-regulated nanoclusters (RuNCs) of ruthenium. The electrochemical behavior of prepared nanocluster film was investigated by using cyclic voltammetry. The electrodeposited nanofilm shows excellent electrocatalytic activity toward enzyme less oxidation of glucose in the natural pH. The deposited film enhances the electron transfer efficiency and reduces the oxidation potential to next to −0.1 V vs. Ag/AgCl. The quantitative determination of glucose without any interference at RuNCs/ITO has obtained in a width dynamic range of 20 µM–1.2 mM with a limit of detection of 20 µM. It could be a good candidate for generating miniaturized glucose biosensor in humane matrices.

Electrosynthesis and characterizations of electrochromic and soluble polymer films based on N- substituted carbazole derivates

Carbazole derivatives are a class of nitrogen-containing aromatic heterocyclic compounds and they not only have various biological activities but also exhibit useful properties as organic materials due to their special structures. In this study, the compounds based on carbazole derivatives (N-positions were occupied by methanol, carboxylic acid, and cyanoethyl) were synthesized via a simple method. The electrochemistry and electropolymerization of these three monomers were investigated and compared with those of different N-substituted with groups attaching on the active sites of the carbazole units. The polymeric films were prepared on ITO/glass substrate by repetitive cyclic voltammetry (CV) scanning of the monomer solutions containing NaClO4-LiClO4 electrolyte dissolved in acetonitrile. The structures of the monomers and polymers were characterized by 1H-NMR, 13C-NMR, and FTIR. The electro-generated polycarbazole films exhibited redox-activity and multichromic properties with increasing potential. The remarkable electrochromic behavior of the films was explained in detail with the help of spectroelectrochemical studies. Photoluminescence spectra and quantum yields were given of polycarbazole samples in solution. In addition, solubility, molecular weight, and conductivity properties of polymers containing N-substituted groups have been discussed further.

Anodic Coating of 1.4622 Stainless Steel with Polydopamine by Repetitive Cyclic Voltammetry and Galvanostatic Deposition

Polydopamine exhibits high potential as coating of materials used for medical devices, antifouling, and corrosion prevention. Repetitive cyclic voltammetry on gold electrodes was used to deposit polydopamine by anodic oxidation. Investigation of polydopamine formation in the pH range 5–8 showed that coating at pH 6.5 permits selective polydopamine formation on the electrode, while auto-oxidation of dopamine in the electrolyte could be suppressed. The optimized conditions then were transferred to stainless steel electrodes. At pH 6.5–6.6, an anodic peak current density of 12.9 μA/mm2 was measured using a plane stainless steel anode in 5 mM dopamine solution. During experimental scale-up, anodic coating of 1.4622 steel plates in galvanostatic experiments led to formation of a colored polydopamine surface, which exhibited reduction of the water contact angle by 13.5°. The controlled anodic polydopamine formation is of a particular value for an economic polydopamine coating of the conductive material in larger-scale applications.

Aqueous surface chemistry of gold mesh electrodes in a closed bipolar electrochemical cell

The influence of the bipolar electrode on the voltammetry observed with a closed bipolar electrochemical cell (CBPEC) goes far beyond simply conducting electrons between the two electrolyte solutions. The surface of each pole of the bipolar electrode may contain redox active functional groups that generate misleading or interfering electrochemical responses. Herein, a 4-electrode CBPEC configuration was studied with the opposite poles of the bipolar electrode resting in separate aqueous and organic electrolyte solutions. Using gold mesh wire electrodes as the poles, we systematically investigated the many experimental variables that influence the observed voltammetry upon addition of a reductant (decamethylferrocene) to the organic phase. External bias of the driving electrodes forced electrons released by decamethylferrocene at the organic pole to flow along the bipolar electrode and reduce redox active surface functional groups at the aqueous pole, such as oxide or hydroxide groups, or carry out the oxygen reduction reaction (ORR) or hydrogen evolution reaction (HER). The 4-electrode CBPEC configuration diminishes capacitive currents, permitting observation of voltammetric signals from electron transfer processes related to surface functional groups at the aqueous pole at much lower scan rates than possible with working electrodes in conventional 3-electrode electrochemical cells. Surface modification, by oxidative or reductive electrochemical pre-treatment, changes the potential window experienced by the aqueous pole in the 4-electrode CBPEC in terms of its position versus the standard hydrogen electrode (SHE) and dynamic range. In a related observation, the electrochemical responses from the surface functional groups on the aqueous pole completely disappear after oxidative pre-treatment, but remain after reductive pre-treatment. The flow of electrons from decamethylferrocene to the surface of the aqueous pole is limited in magnitude, by the decamethylferrocene concentration, and kinetically limited, due to decamethylferrocene diffusion to the organic pole, in comparison to the infinite supply of electrons delivered to the surface of a working electrode in a 3-electrode cell. This unique feature of the 4-electrode CBPEC facilitates a very gradual evolution of the surface chemistry at the aqueous pole, for example from fully oxidised after oxidative pre-treatment to a more reduced state after repetitive cyclic voltammetry cycling. Perspective applications of this slow, controlled release of electrons to the electrode surface include spectroelectrochemical analysis of intermediate states for the reduction of metal salts to nanoparticles, or conversion of CO2 to reduced products at catalytic sites. The use of indium tin oxide (ITO) electrodes in CBPEC experiments for specific reactions is recommended to avoid misleading or interfering electrochemical responses from redox active functional groups prevalent on metallic surfaces. However, the electronic bridge to implement entirely depends on the reaction under study, as ITO also has drawbacks such as a lack of electrocatalytic activity and the requirement of an overpotential due to its semiconducting nature.

The effect of surface modification on the corrosion protection ability of the passive films of sensitized UNS S31803 duplex stainless steel

ABSTRACTThe influence of sensitisation heat treatment, surface roughness and repetitive cyclic voltammetry (RCV) procedure (that was used to create passive films on the surface of sensitised samples) on the corrosion behaviour of UNS S31803 duplex stainless steel was evaluated using sodium hydroxide etching, double-loop electrochemical potentiodynamic reactivation (DLEPR), potentiodynamic polarisation, Mott–Schottky analysis, X-ray diffraction and optical microscopy techniques. The results showed that prolonged sensitisation time leads to the formation of defective passive films on the surface. In addition, as the substrate surface roughness decreases, the defect concentration in the resulting passive film decreases. Moreover, thick passive films that were created at a high number of RCV cycles contain fewer defects than the thin ones. Finally, the specimens with smooth surfaces, thick passive films and low degree of sensitisation exhibit high corrosion resistance due to their intact passive layers formed on their surfaces.

Delicate topotactic conversion of coordination polymers to Pd porous nanosheets for high-efficiency electrocatalysis

Two-dimensional noble metal-based nanosheets with high porosity represent a class of promising electrocatalysts due to their highly open structure feature, increased atomic utilization efficiency and thus boosted electrocatalytic performances. Nevertheless, it still remains greatly challenging to fabricate highly porous metal nanosheets through a feasible and general approach to date. Herein we present a novel coordination polymer (CP)-engaged approach to create a class of porous 2D Pd nanosheets for enhancing the electrocatalysis of small molecules through a two-step topotactic conversion reaction. The pre-synthesized Hofmann-type CP square nanoplates are firstly converted into Pd-Ni oxide through a mild calcination and eventually transformed into Pd porous nanosheets after repetitive cyclic voltammetry (CV) treatments in H2SO4 solution. Benefiting from intriguing structural advantages, the formed porous Pd nanosheets exhibit greatly improved catalytic performance toward the electrooxidation of liquid fuels (e.g., CH3OH and HCOOH) and oxygen reduction reaction (ORR) as compared with commercial Pd black catalyst. The present synthetic strategy would provide a new perspective for the rational fabrication of noble metal-based porous nanosheets with extraordinary functionalities.

Cr2O3-modified graphite felt as a novel positive electrode for vanadium redox flow battery

In this work, we investigate a facile modification approach for depositing novel electrocatalyst of chromium oxide on graphite felt via impregnation in conjunction with unltrasonication in order to improve the electrochemical performance of the positive electrode in the vanadium redox flow battery (VRFB). The modified graphite felt with an ultra-thin coating layer of Cr2O3 not only promotes the activity and reversibility of VO2+/VO2+ redox reactions, but also exhibits excellent stability in repetitive cyclic voltammetry. The flow cell employing the modified graphite felt electrodes demonstrates enhanced performance with voltage efficiency and energy efficiency of 75.9% and 67.6% at a high current density of 150 mA cm−2, which are much higher than that of 66.9% and 56.8% obtained from the cell employing pristine graphite felt. Moreover, the utilization depth of the cell is significantly enhanced as the discharge capacity increases by 83.6%. The cycling test demonstrates the stability of the Cr2O3 coating layer on graphite felt, where no significant decay in efficiencies was observed. The results verify stable and significantly enhanced catalytic effect of chromium oxide in providing active sites and promoting the electrochemical performance of graphite felt in the VRFB.

Redox-active and fluorescent pyrene-based triarylamine dyes and their derived electrochromic polymers

Two triarylamine derivatives, DPPA-2(NHCO-TPA) and DPPA-2(NHCO-NPC), composed of a central diphenylpyrenylamine (DPPA) unit via amide groups linked to two triphenylamine (TPA) or N-phenylcarbazole (NPC) sides are developed as an electroactive precursor to prepare electrochromic films through electrochemical polymerization. The dilute solutions of these two DPPA-containing compounds showed notable fluorescence and solvatochromic shifts. Electroactive polymeric films could be electrodeposited on the ITO electrode surface by repetitive cyclic voltammetry scanning of their dichloromethane solutions containing dissolved 0.1 M tetrabutylammonium perchlorate (TBAP) between 0 and 1.5 V. The polymer films displayed multi-staged redox processes and color changes upon electrochemical oxidation. Spectroelectrochemistry and electrochromic switching stability of the polymers were investigated. Simple single-layer electrochromic devices were also fabricated and tested.

Comparative Study of the ORR Activity and Stability of Pt and PtM (M = Ni, Co, Cr, Pd) Supported on Polyaniline/Carbon Nanotubes in a PEM Fuel Cell.

The oxygen reduction reaction (ORR) activity and stability of platinum (Pt) and PtM (M = Ni, Co, Cr, Pd) supported on polyaniline/carbon nanotube (PtM/PANI-CNT) were explored and compared with the commercial Pt/C catalyst (ETEK). The Pt/PANI-CNT catalyst exhibited higher ORR activity and stability than the commercial Pt/C catalyst even though it had larger crystallite/particle sizes, lower catalyst dispersion and lower electrochemical surface area (ESA), probably because of its high electrical conductivity. The addition of second metal (M) enhanced the ORR activity and stability of the Pt/PANI-CNT catalyst, because the added M induced the formation of a PtM alloy and shifted the d-band center to downfield, leading to a weak chemical interaction between oxygenated species and the catalyst surface and, therefore, affected positively the catalytic activity. Among all the tested M, the addition of Cr was optimal. Although it improved the ORR activity of the Pt/PANI-CNT catalyst slightly less than that of Pd (around 4.98%) in low temperature (60 °C)/pressure (1 atm abs), it reduced the ESA loss by around 14.8% after 1000 cycles of repetitive cyclic voltammetry (CV). In addition, it is cheaper than Pd metal. Thus, Cr was recommended as the second metal to alloy with Pt on the PANI-CNT support.

Electrosynthesis of redox-active and electrochromic polymer films from triphenylamine-cored star-shaped molecules end-capped with arylamine groups

Four starburst molecules with a triphenylamine (TPA) core through the amide group linked to the terminal triphenylamine or (N-phenyl)carbazole (NPC) unit, coded as T-3(NHCO-TPA), T-3(NHCO-NPC), T-3(CONH-TPA), and T-3(CONH-NPC), were synthesized and their electrochemistry and electropolymerization were investigated. The oxidation potential and the stability of the oxidized forms of the starbursts are affected by the orientation of amide linkage and the structure of terminal triarylamine unit. Robust polymeric films could be built onto ITO/glass surface by repetitive cyclic voltammetry (CV) of the T-3(NHCO-TPA) solution containing an electrolyte. The electrodeposited films exhibited reversible electrochemical processes and strong color changes upon electro-oxidation, which can be switched by potential modulation. The electrochromic behavior of the film was clearly interpreted on the basis of spectroelectrochemical studies. T-3(CONH-TPA) did not undergo electropolymerization effectively. T-3(CONH-NPC) also could electrochemically polymerize to polymer films upon repeated CV scans. However, their electrochromic switching stability is less than that of the polymer film from T-3(NHCO-TPA).

Biofunctionalization of Nerve Interface via Biocompatible Polymer-Roughened Pt Black on Cuff Electrode for Chronic Recording.

Peripheral nerve cuff electrodes with roughened Pt black (BPt) are coated with polyethylene glycol (PEG) and Nafion (NF). Although the influence of coated PEG and Nafion on roughened BPt on the electrical properties is weak, the cuff electrode with BPt/PEG and BPt/Nafion exhibits some very important properties. For example, it markedly decreases interfacial impedance, increases charge storage capacity (CSC) due to retaining the BPt surface structure, good stability without exfoliation in repetitive cyclic voltammetry scanning because it is protected by PEG or Nafion coating. In cell viability test, Nafion-coated BPt does not show cytotoxicity to rat Schwann cell line (S16) at 24 and 72 h with the Nafion coating ranging from 0.1 to 10 mg cm-2 . In addition, real-time polymerase chain reaction (PCR) analysis indicates that Schwann cell differentiation (S100 calcium-binding protein B, myelin basic protein, peripheral myelin protein 22), proliferation (proliferating cell nuclear antigen, cyclin-dependent kinase 1 (CDK1)), and adhesion molecules (neural cell adhesion molecule, laminin, fibronectin) are upregulated up to 5 mg cm-2 of Nafion. In animal study, the BPt/Nafion reduces infiltration of fibrotic tissue with high axonal maintenance with upregulation of proliferation (CDK1), adhesion (laminin, neuronal cell adhesion molecule), and neurotrophic factor receptor-related (gdnf family receptor alpha 1) mRNA expressions.