Characterization and Electrochromic Properties of Poly(2,3,5,6-Tetrafluoroaniline): Progress Towards a Transparent Conducting Polymer

Electrochromic films of poly(2,3,5,6-tetrafluoroaniline) (PTFA) were formed on ITO substrates from aqueous solutions utilising perchloric acid (HClO4) as dopant. Electrochemical and spectroscopic characterization of PTFA films was performed in background electrolyte and in solutions with the addition of tetrahydrofuran. When the PTFA film was removed from its growth medium, a significant decrease in the faradaic current was observed. The faradaic response increased on addition of tetrahydrofuran which facilitates ion movement through the polymer matrix. PTFA films deposited on ITO substrate were orange and light orange in the oxidized and reduced forms, respectively. The films were ca. 25 nm in thickness. In aqueous solution the films showed a porous structure with a non-uniform distribution of pore diameters. In the presence of tetrahydrofuran a less porous structure was observed

Electrodeposition and Characterisation of Copolymers Based on Pyrrole and 3,4-Ethylenedioxythiophene in BMIM BF4 Using a Microcell Configuration

Electrochemical copolymerization of pyrrole (Py) and 3,4-ethylenedioxythiophene (EDOT) was performed in an ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, (BMIM BF4) employing a ‘micro-cell’ in order to use the materials efficiently. Characterization of the copolymers formed on an ITO substrate was performed for different Py: EDOT ratios (1:2, 1:1, 2:1) in both aqueous and ionic liquid electrolytes. Electrochemical and spectroelectrochemical analysis revealed that the properties of the copolymer depend upon the Py/EDOT monomer ratio used. The copolymer PPy-co-PEDOT (2:1) displayed good stability, a switching time of 20 s and a colouration efficiency of 101.3 C-1cm2. The presence of Py in the copolymer stabilised the polaron state of the copolymer and allowed greater ion mobility compared to the PEDOT alone

Antimicrobial enzymatic biofuel cells†

peer-reviewedA compact antibiotic delivery system based on enzymatic biofuel cells was prepared, in which ampicillin was released when discharged in the presence of glucose and O2. The release of ampicillin was effective in inhibiting the growth of bacterium Escherichia coli as confirmed by ex situ and in situ release studies in culture media

Adsorption of malachite green and alizarin red S dyes using Fe-BTC metal organic framework as adsorbent

peer-reviewedSynthetic organic dyes are widely used in various industrial sectors but are also among the most harmful water pollutants. In the last decade, significant efforts have been made to develop improved materials for the removal of dyes from water, in particular, on nanostructured adsorbent materials. Metal organic frameworks (MOFs) are an attractive class of hybrid nanostructured materials with an extremely wide range of applications including adsorption. In the present work, an iron-based Fe-BTC MOF, prepared according to a rapid, aqueous-based procedure, was used as an adsorbent for the removal of alizarin red S (ARS) and malachite green (MG) dyes from water. The synthesized material was characterized in detail, while the adsorption of the dyes was monitored by UV-Vis spectroscopy. An optimal adsorption pH of 4, likely due to the establishment of favorable interactions between dyes and Fe-BTC, was found. At this pH and at a temperature of 298 K, adsorption equilibrium was reached in less than 30 min following a pseudo-second order kinetics, with k” of 4.29 × 10−3 and 3.98 × 10−2 g·mg−1 min−1 for ARS and MG, respectively. The adsorption isotherm followed the Langmuir model with maximal adsorption capacities of 80 mg·g−1(ARS) and 177 mg·g −1 (MG), and KL of 9.30·103 L·mg−1 (ARS) and 51.56·103 L·mg−1 (MG)

Coupled immobilized bi-enzymatic flow reactor employing cofactor regeneration of NAD+ using a thermophilic aldehyde dehydrogenase and lactate dehydrogenase

The use of enzymes in biochemical processes is of interest due to their ability to work under mild conditions while attaining high reaction rates. A limitation in the use of enzymes such as oxidoreductases on a large scale lies with their requirement for costly cofactors, e.g. NAD+, in stoichiometric quantities. Cofactor regeneration mechanisms using bienzymatic recycling systems is an attractive way to increase productivity and efficiency. The thermophilic enzyme aldehyde dehydrogenase (ALDHTt) was immobilized directly from E. coli cell lysate, containing the expressed enzyme, onto Ni2+ activated Sepharose(R). The system displayed a rate of conversion of approx. 63% NAD+ with reuse achievable for up to 5 cycles and residual activity of the enzyme upon storage of 93% after 7 days. L-Lactate dehydrogenase was immobilized in a second reactor module downstream of ALDHTt via two different methods, electrochemical entrapment in poly (3,4-ethylenedioxypyrrole) (PEDOP) and covalent attachment on glyoxyl agarose. Both reactors allowed for up to 100% conversion of NADH, however LDH@Agarose proved superior in terms of reuse and storage. LDH@Agarose displayed no reduction in activity after 6 cycles of use and retained 98% activity following 56 days storage. A coupled reactor containing immobilized ALDHTt-LDH was operated with the substrates hexanal, benzaldehyde, terephthalaldehyde and p-tolualdehyde. A particular advantage of the system is its ability to preferentially oxidise a single aldehyde group in substrates containing two aldehyde functional groups. The reactor demonstrated efficient cofactor regeneration under continual operation for up 24 h, with enhanced product yields

Organic dyes containing coplanar dihexyl-substituted dithienosilole groups for efficient dye-sensitised solar cells

peer-reviewedA chromophore containing a coplanar dihexyl-substituted dithienosilole (CL1) synthesised for use in dye-sensitised solar cells displayed an energy conversion efficiency of 6.90% under AM 1.5 sunlight irradiation. The new sensitiser showed a similar fill factor and open-circuit voltage when compared with N719. Impedance measurements showed that, in the dark, the charge-transfer resistance of a cell using CL1 in the intermediate-frequency region was higher compared to N719 (69.8 versus 41.3 Omega). Under illumination at AM 1.5G-simulated conditions, the charge-transfer resistances were comparable, indicative of similar recombination rates by the oxidised form of the redox couple. The dye showed instability in ethanol solution, but excellent stability when attached to TiO2. Classical molecular dynamics indicated that interactions between ethanol and the dye are likely to reduce the stability of CL1 in solution form. Time-dependent density functional theory studies were performed to ascertain the absorption spectrum of the dye and assess the contribution of various transitions to optical excitation, which showed good agreement with experimental results.PUBLISHEDpeer-reviewe