Glucose oxidase electrodes based on microstructured polypyrrole films

Highly sensitive glucose oxidase (GOD) electrodes were fabricated on the basis of microstructured polypyrrole (PPy) films. The microstructures of the PPy films had a morphology like cups and were arranged in a density of approximately 4000 units/cm². GOD was immobilized in microstructured PPy films coated on a Pt or stainless steel (SS; AISI 321) substrate electrode. The GOD/PPy/Pt electrode showed a linear response to glucose concentrations in the range of 0–17 mM at a potential of 0.4 V (vs a saturated calomel electrode). Its sensitivity was measured to be approximately 660 nA/(mM cm²) at 15°C, and the response time (t_95%) was approximately 20 s. In comparison, the sensitivity of the GOD/PPy/Pt electrode based on a flat PPy film was only approximately 330 nA/(mM cm²) under the same conditions. The sensitivity of the microstructured GOD/PPy/Pt electrode could be increased to as high as approximately 2400 nA/(mM cm²) at 37°C. The microstructured GOD/PPy/SS electrode had a sensitivity of approximately 550 nA/(mM cm²) and a t_95% value of approximately 30 s at 15°C and 0.4 V. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2550–2554, 2005     

PMMA/棉花纤维素复合薄膜的制备及性能

为改善聚甲基丙烯酸甲酯(PMMA)的热性能和力学性能,以经过预处理的棉花纤维素为增强体,将PMMA与棉花纤维素溶液按不同比例混合,利用溶液浇铸法制备PMMA/棉花纤维素复合薄膜,并利用热重分析、透光性分析以及拉伸性能测试研究了不同棉花纤维素含量的PMMA/棉花纤维素复合薄膜的性能。结果表明,与PMMA薄膜相比,PMMA/纤维素复合薄膜的热稳定性和力学性能均有所提升,PMMA/纤维素复合薄膜的热分解温度提高8.3%;随着棉花纤维素含量从0增加到15%,拉伸强度从10.53 MPa提升到55.95 MPa,最高提升了431%。此外,复合薄膜的光透过率随着棉花纤维素含量的增加而降低。当棉花纤维素含量为7.5%时,复合薄膜不仅具有良好的力学性能,而且具有较高的透光率,综合性能较好。     

Polypyrrole/polyaniline conductive films obtained electrochemically on polycarbonate‐coated platinum electrodes

In this study, two‐component free‐standing films were obtained by coating a polycarbonate (PC)‐coated Pt electrode first with polypyrrole (PPy) in an organic medium and then polyaniline (PAn) in an aqueous medium using an electrochemical technique. The amount of PPy and PAn contained in the films was controlled by varying the electrolysis time. The PC/PPy/PAn films were characterized by cyclic voltammetry, conductivity, FTIR and UV–visible spectrophotometry, and thermogravimetric analysis. The resistance change of the films was determined in the temperature range of ?15 to 120 °C and their temperature sensor properties were investigated. © 2002 Society of Chemical Industry     

Fabrication of barium titanate nanoparticles‐polymethylmethacrylate composite films and their dielectric properties

A method for incorporating barium titanate (BT) nanoparticles into polymethylmethacrylate (PMMA) is proposed to prepare composite films with a high dielectric constant and high transparency. BT particles with particle sizes of 7.8–24.0 nm and crystal sizes of 8.60–17.7 nm were synthesized with a complex alkoxide method. Surface of the BT particles was modified with 3‐methacryloxypropyltrimethoxysilane to introduce double bonds that was grafted with PMMA. The PMMA‐grafted BT particles were suspended in PMMA/N‐methyl‐2‐pyrrodinone solution and spin‐coated onto glass substrates to prepare the PMMA/BT composite films. The surface modification gave composite films having smooth surfaces and high transparency. An increase in BT particle size and BT volume fraction in the film tended to increase the dielectric constant while keeping the dissipation factor around 5%. The dielectric constant of the film prepared for a particle size of 24.0 nm at 39 vol% attained a value of 19.8 that was around four times higher than that of the pure PMMA film. The dielectric constants of the BT particles estimated by the application of Lichtenecker's mixing model to the composite films were 75.3, 105.1, and 166.3 for particle sizes of 7.8, 11.0, and 24.0 nm, respectively. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Abrasion resistance of ceramic thin films of ZrO2/SiO2 on stretched grade polymethyl methacrylate substrates

Abrasion resistance of stretched grade polymethyl methacrylate (PMMA) was increased by using the sol–gel method to have it coated with a ZrO₂/SiO₂ thin film. Different molar ratios of Zr(OPr)₄/Si(OPr)₄ sols were prepared as precursors with propanol. These sols were used for dip-coating the stretched PMMA surfaces to establish very smooth thin films of amorphous Zr–O–Si. Fourier Transform Infrared spectroscopy (FT-IR) was employed to study vibrations of Zr–O–Si bonds within the thin film. The phase analysis was undertaken via X-ray Diffraction (XRD) method. The morphology and thickness of coatings on PMMA were investigated by means of Scanning Electron Microscopy (SEM). The results showed that coating had an amorphous structure with its thickness within the range of 80–100 nm. The water contact angle of PMMA substrates altered from 73° before coating to less than 64° after coating. Once coated, the PMMA substrate had its transparency characteristic (within the UV–vis region) increased. Furthermore, the influences of thermal treatment temperature and molar ratio of precursors (Zr(OPr)₄/Si(OPr)₄) on abrasion resistance of the coatings were studied.     

Water-soluble polyaniline/graphene prepared by in situ polymerization in graphene dispersions and use as counter-electrode materials for dye-sensitized solar cells

Water-soluble polyaniline/graphene nanocomposites have been prepared via a simple in situ polymerization of aniline in graphene dispersion. TEM measurement confirmed that polyaniline was homogeneously coated on the graphene sheets. The nanocomposites solution can be used for film fabrication by common technology, such as drop coating. When these different polyaniline/graphene nanocomposites were applied as the counter electrode materials for dye-sensitized solar cells, the short-circuit current density and power-conversion efficiency of the devices were measured to be 12.19 mA cm⁻² and 4.46%, respectively, which was comparable to 5.71% for the cell with a Pt counter electrode under the same experimental conditions.     

Electrochemical preparation of poly(o‐toluidine) film and its application as a permselective membrane

Poly(o‐toluidine) films were electrochemically synthesized on Pt electrodes at a constant potential (0.75 V versus Ag/AgCl) from a deoxygenated aqueous solution of 0.1M toluidine dissolved in 0.1M KCl. To form permselective polymeric film electrodes, poly(o‐toluidine) films at different thicknesses were prepared by varying the amount of charge consumed during electrochemical polymerization. Then, experimental parameters (e.g., concentrations of monomer and electrolyte and pH of the phosphate buffer salt solution) affecting the polymeric film thickness were optimized. Permeation of the various electroactive and nonelectroactive species such as ascorbic acid, oxalic acid, hydrogen peroxide, lactose, sucrose, and urea through the optimized poly(o‐toluidine)‐coated electrodes was investigated using a chronoamperometric technique. From experimental results, it was found that a poly(o‐toluidine)‐coated electrode permitted the oxidation of hydrogen peroxide and prevented the permeation of the mentioned electroactive and nonelectroactive species. In other words, it was seen that this polymeric electrode responded to only hydrogen peroxide selectively. Thus, it has been claimed that a poly(o‐toluidine)‐coated Pt electrode can be used as a permselective polymeric membrane to overcome interference problems occurring in the hydrogen peroxide‐based biosensor applications. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2141–2146, 1999     

The electrochemical synthesis of poly(aniline-co-o-anisidine) on copper and their corrosion performances

The copolymer films PANI-co-POA and poly(aniline-co-o-anisidine) were carried out on copper (Cu) electrode, by applying two different scan rates (20 and 50 mV s⁻¹) and using two different thicknesses at high scan rate. Synthesizes were achieved under cyclic voltammetric conditions from 0.075 M aniline and 0.075 M o-anisidine containing sodium oxalate solutions. The synthesized copolymer films were strongly adherent and homogeneous in both cases. AC impedance spectroscopy (EIS), anodic polarization plots and open circuit potential–time curves were used to evaluate the corrosion performance of copolymer coated and uncoated electrodes in 3.5% NaCl. It was shown that the copolymer film coated at low scan rate exhibited a better property initially when compared with the copolymer film produced at high scan rate. However, it could not resist the attack of corrosion products, in longer time and meanwhile its barrier property significantly diminished. It was found that the thin copolymer film produced at high scan rate by its catalysing effect led to the formation of highly protective copper oxides on the surface whereby providing a better protection for long exposure times. It also emerged that the corrosion resistances of thin copolymer film produced at high scan rate and copolymer film synthesized at low scan rate were almost same and relatively higher for much longer periods when compared with the one observed for bare copper electrode.     

Protective properties of polyaniline and poly(aniline-co-o-anisidine) films electrosynthesized on brass

Polyaniline and poly(aniline-co-o-anisidine) films were deposited on brass (Cu40Zn). The synthesis processes of homo and copolymer film were carried out under cyclic voltammetric condition from 0.12 M aniline and 0.06 M aniline + 0.06 M o-anisidine containing 0.2 M sodium oxalate solutions. Homo and copolymer films were characterized by scanning electron microscopy (SEM). SEM images clearly show that one of the brass electrodes was covered with a black copolymer film of strongly adherent homogeneous characteristic while the other one with a porous dark green homo polymer one. The corrosion performances of coated and uncoated electrodes in 3.5% NaCl were evaluated with the help of AC impedance spectroscopy, anodic polarization plots and open circuit potential–time curves. The protective effect of homo and copolymer films formed on brass grew in parallel with extended exposure time. It was only observed with copolymer-coated electrode that changes in the charge transfer resistance of copolymer-coated electrode were related to strong adsorption of copolymer film on the brass surface which led to the formation of a protective oxide layer due to its catalytic behaviour.     

Electrochemically oxidative polymerization of aniline in aromatic copolyamide matrix

Composite films from polyaniline (PAn) and a copolyamide, poly(p-phenylene terephthalamide/diphenylether terephthalamide) (PPDTA), have been obtained by the electrochemical polymerization of aniline on a PPDTA/Pt (or Ni, stainless steel) working electrode in water or a mixed-solvent electrolyte solution. This PAn/PPDTA composite has higher mechanical properties than does the PPDTA matrix and the electrical conductivity close to pure PAn. The electrochemical polymerization of aniline can be carried out only in the electrolyte solution with PH < 2. The PAn/PPDTA film is electroactive material and very stable in air. © 1993 John Wiley & Sons, Inc.     

Multilayer photoactive nanocolloidal PPy:PSS as a novel substitute for Pt free counter electrode in DSSC

Water dispersible and highly processable, Polypyrrole (PPy) nanocolloidal particles were synthesized by chemical oxidation polymerization with 15 wt % of anionic polyelectrolyte poly(styrene sulfonate) (PSS) at 5°C has been reported in this work. This polymer composite (PPy:PSS) was competent with conventional Pt counter electrode (CE) when compared for dye sensitized solar cells (DSSCs). Morphological analysis revealed smooth and spherical shaped nanoparticles of PPy. Interaction between the SO₃H groups and Py units in PPy improved the thermal stability of PPy with higher doping levels of PSS. The nanocolloidal solution was spin coated at 4000 rpm. The layer by layer, self‐assembled multilayer thin films were used as CE in DSSCs. There was a linear dependence of DSSCs performance with film roughness for the self‐assembled multilayer PPy:PSS films. Single layer films showed better electrocatalytic behavior than multilayer films. All the PPy:PSS films had good electrochemical stability. The DSSC efficiency of 3.40% was observed for chemically oxidized PPy with 15 wt % PSS for single layer film, with a highest FF of 0.7154. The low cost, good performance, rapid and simple fabrication method of PPy:PSS composite modified CE could be a potential alternative for Pt in the DSSCs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43114.     

Resistive switching characteristics of sputtered AlN thin films

AlN thin films were deposited on Pt/Ti/SiO₂/Si substrates using a radio-frequency magnetron sputtering technique. The effect on the switch current–voltage characteristics of four different materials in the electrode fabricated on top of the AlN film was investigated. The deposition time and nitrogen content in the sputtering atmosphere were changed to adjust the thickness and composition of the AlN thin films, respectively. The influence of film thickness and content on the resistive switching behavior was discussed. The possible mechanism of resistive switching was examined via analyses of the electrical resistive switching characteristics, forming voltage, and on/off current ratio.     

Electrochemical preparation of electrically conducting polyurethane/polyaniline composite

Composite films from polyaniline (PANi) and polyurethane (PU), with flexibility and mechanical strength similar to pure PU and conductivity close to pure PANi, have been obtained by electropolymerizing amiline on a PU/Pt electrode in water/acetonitrile/ethylen glycol electrolyte solution. In the composite films, PANi is dispersed, in the form of particulate, inside and on the inner surface of the PU substrates. It is found that the electropolymerization reaction of aniline proceeds much faster in basic solution and composite film as prepared shows higher conductivity than that in acidic solution. PANi in PU/PANi composite film is protonic-acid-doped and is conducting even in case it is electropolymerized in a basic electrolyte solution.     

Poly(malachite green) film: Electrosynthesis, characterization, and sensor application

Poly(malachite green) films were synthesized electrochemically on the glassy carbon electrode in the potentiodynamic mode. The characterization and growth mechanism of as-prepared films were studied with FT-IR spectroscopy, UV-vis spectroscopy, cyclic voltammetry, chronocoulometry, and electrochemical impedance spectroscopy. Charge transfer and ion transport of poly(malachite green) films were investigated in the aqueous solutions with different types of supporting electrolytes. The poly(malachite green) film coated glassy carbon electrode showed catalytic ability towards ascorbic acid and dopamine. The difference of the anodic peak potential of ascorbic acid on the poly(malachite green) film modified electrode from that of dopamine was 180 mV. Based on their voltammetric responses, the poly(malachite green) film coated glassy carbon electrode was utilized as an electrochemical sensor for the content determination of ascorbic acid and dopamine simultaneously and separately in pharmaceutical and injections.     

Comparison of the growth process and electrochemical properties of polyaniline films prepared by pulse potentiostatic and potentiostatic method on titanium electrode

Polyaniline (PANI) films were deposited on titanium (Ti) electrode in a bath containing 0.3 mol L^?1 aniline and 1 mol L^?1 HNO₃ by pulse potentiostatic method (PPM) and potentiostatic method (PM). The chronoamperograms during aniline polymerization were recorded, and the morphologies of PANI films prepared with different polymerization periods were examined under scanning electron microscope. The difference between the processes of PANI films growth was studied. The growth processes of PANI films prepared by PPM and PM are divided into two stages. For both PPM and PM, the first stage corresponds to the formation of a compact granular PANI layer on the surface of Ti electrode. The second stage corresponds to further growth of PANI film on the surface of the compact granular PANI film. However, the PANI films prepared by PPM and PM show different morphologies in this stage. In addition, the electrochemical properties of the PANI films prepared by PPM and PM are obviously different. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 458–463, 2007     

底电极原位退火与沉积温度对PZT薄膜性能影响研究

采用磁控溅射工艺,在Pt/Ti底电极上沉积锆钛酸铅(PZT)薄膜,研究了原位退火温度与底电极沉积温度对溅射PZT薄膜结晶取向、微观结构、介电性能、铁电性能及疲劳性能的影响。X射线衍射(XRD)和扫描电子显微镜(SEM)分析结果表明,随着电极沉积温度升高,Pt晶粒尺寸增大,随着退火温度升高,PZT薄膜致密性变差。对室温制备的Pt/Ti底电极进行200 ℃原位退火30 min后,易于促进PZT薄膜沿(100)择优取向,而高温制备或经高温退火处理的Pt/Ti底电极更有利于PZT薄膜的(111)晶向生长。电学性能分析表明,室温制备的Pt/Ti底电极在经200 ℃原位退火30 min后,其PZT薄膜介电性能最优,同时展现较高的剩余极化强度和最小的矫顽场强,经历10⁸次极化翻转后,初始极化下降仅为11％。     

Graphene aerogels as a highly efficient counter electrode material for dye-sensitized solar cells

Graphene aerogels (GAs) prepared with an organic sol–gel process, possessing a high specific surface area of 814 m²/g and a high electric conductivity of 850 S/m, are applied as a counter electrode material for dye-sensitized solar cells (DSSCs). The performance of the GA as the counter electrode material is found to be dependent on its film thickness, with thicker films offering more surface areas for the involved catalytic reduction reaction but at the same time increasing the charge and mass transport resistances. At an optimum GA film thickness of 4.9 μm, a power conversion efficiency of 96% of that achieved with a Pt counter electrode based DSSC is obtained. In addition, a thinner GA film of 1.7 μm, when loaded with Pt of 1 mol% through a photo-reduction process, achieves a power conversion efficiency of 98% of that obtained with a Pt counter electrode based DSSC. The excellent performances of the GA-based counter electrodes are manifested with electrochemical impedance analyses and cyclic voltammetry based catalytic activity analyses.     

Study of graphene nanoflake as counter electrode in dye sensitized solar cells

Graphene nanoflake (GNF) films have been fabricated on a fluorine doped tin oxide (FTO) glass using a doctor blade method and thermally annealed in air and argon ambient at various temperatures. The GNF/FTO thin films were employed as a counter electrode for dye sensitized solar cells (DSSCs). Results showed the GNF/FTO film could enhance the power conversion efficiency (PCE) of DSSC devices more effectively when annealed in argon ambient rather than in air and at annealing temperatures higher than 380 °C. The PCE enhancement was mainly due to the lowered oxygen concentration in the film and the elevated electrical conductance. A PCE of 6.08% or 88% of that with a Pt counter electrode has been achieved for DSSCs with a GNF counter electrode, suggesting that GNF is a highly potential candidate to replace Pt catalyst.     

Enhanced performance of a dye-sensitized solar cell with an electrodeposited-platinum counter electrode

A counter electrode was prepared for a dye-sensitized solar cell (DSSC) through electrochemical deposition of mesoporous platinum on fluorine-doped tin oxide glass in the presence of a structure-directing nonionic surfactant, octaethylene glycol monohexadecyl ether (C₁₆EO₈). The DSSC fabricated with the electrochemically deposited Pt (ED-Pt) counter electrode rendered a higher solar-to-electricity conversion efficiency of 7.6%, compared with approximately 6.4% of the cells fabricated with the sputter-deposited or most commonly-employed thermal deposited Pt counter electrodes. This enhanced efficiency is attributed to the higher short-circuit photocurrent arising from the increases in the active surface area and light reflection as well as the decrease in the sheet resistance of the ED-Pt film, relative to those of the Pt films prepared by the other two deposition methods. The sputter-deposited Pt film yielded almost the same photovoltaic characteristics as the thermal deposited Pt film. The Pt films were characterized by FE-SEM, AFM, cyclic voltammetry, chronoamperometry, electrochemical impedance spectroscopy, sheet resistance measurements, adhesion tests, and light reflection tests.     

The influence of chemical passivation on the PZT/Pt electrode interface

It has been recognized that the interdiffusion of atomic species between a PZT film and the Pt bottom electrode leads to the gradual degradation of a PZT capacitor. In order to prevent this interdiffusion, experimental studies on chemical passivation to the bottom electrode surface were carried out by the sulfurization method. It was observed that a sulfur layer was built up on the Pt substrate with small grains, which resulted in a structural change at the Pt surface. Atomic force microscopy (AFM) showed that the film roughness of the Pt surface was increased by sulfur treatment. Pb(Zr_0.5Ti_0.5)O₃(PZT) thin films were prepared on a Pt/Ti/SiO₂Si bottom electrode by spin-coating techniques. The microstructure and the preferred orientation of the PZT films were shown to depend on the sulfur-treated electrode. The PZT capacitor on a clean Pt electrode was confirmed to be ferroelectric with Pr=17.7 μC/cm² and Ec=65 kV/cm from the P-E hysteresis curves. The fatigue behavior of a PZT film capacitor prepared on a sulfur-treated one was observed to be relaxed, but the absolute value of Pr was paid off.