Yongkeun Son

Ionic interactions in polyacrylonitrile/polypyrrole conducting polymer composite

A conducting polymer composite was prepared by the postpolymerization of pyrrole in a polyacrylonitrile (PAN) matrix film. To enhance the electrostatic interaction between the two phases, a small amount of a sulfonate or a carboxylate (COO−) group was incorporated into the PAN structure. The presence of electrostatic interaction between the conducting polypyrrole and the anion-containing PAN copolymer was elucidated by examination of the morphology and the electrical properties of the composite. The aromatic sulfonate-containing matrix provided the composite with the best results in the electrical conductivity, the environmental stability of conductivity, and the morphological property.

IN-SITU FORMATION OF GOLD NANOPARTICLE/CONDUCTING POLYMER NANOCOMPOSITES

Poly(3,4-ethylenedioxythiophene)/gold (PEDOT/Au) nanocomposites were prepared by in-situ redox reaction using PEDOT in the neutral state and AuCl3 as an oxidant. AuCl3 had a sufficient power to oxidize the neutral PEDOT film while it reduced to form gold nanoparticles in the polymer matrix. It was observed that the rate of redox reaction was strongly influenced by the solvent. Finally, the formation and coalescence of gold nanoparticles was clearly demonstrated by SEM and XPS experiments, and a rapid drop in film resistance was also monitored during the redox reactions.

Characteristics of Indium Tin Oxide (ITO) Nanoparticles Recovered by Lift-off Method from TFT-LCD Panel Scraps

In this study, indium-tin-oxide (ITO) nanoparticles were simply recovered from the thin film transistor-liquid crystal display (TFT-LCD) panel scraps by means of lift-off method. This can be done by dissolving color filter (CF) layer which is located between ITO layer and glass substrate. In this way the ITO layer was easily lifted off the glass substrate of the panel scrap without panel crushing. Over 90% of the ITO on the TFT-LCD panel was recovered by using this method. After separating, the ITO was obtained as particle form and their characteristics were investigated. The recovered product appeared as aggregates of particles less than 100 nm in size. The weight ratio of In/Sn is very close to 91/9. XRD analysis showed that the ITO nanoparticles have well crystallized structures with (222) preferred orientation even after recovery. The method described in this paper could be applied to the industrial recovery business for large size LCD scraps from TV easily without crushing the glass substrate.

Recovery of indium tin oxide (ITO) and glass plate from discarded TFT-LCD panels using an electrochemical method and acid treatment

The recovery of ITO and the glass substrate from discarded TFT-LCDs, without crushing the glass substrate, was done by using an electrochemical method and acid treatments. Anodic conditions did not show any redox reaction of the ITO except oxygen evolution. The oxygen evolution lifted the ITO layer off the glass substrate with the remaining colour filer and black matrix. Recovery of the ITO was 75%, but it showed an In–Sn ratio of 15.9:1. The recovered ITO was not suitable for reuse directly. It may be that it needed the addition of extra Sn. However, this work presented a new process for the resource circulation of the indium from discarded LCD panels. The free glass substrate was then recovered after removing the colour filter and black matrix by using an acid solution. The optical transmittance of the recovered glass substrate was about 90% in the visible region, and the average roughness was 0.96 nm.

Synthesis and characterization of a soluble and transparent conducting polymer, poly(3,4-ethylenedioxythiophene)

Abstract A soluble conducting polymer, poly(3,4-ethylenedioxythiophene), has been prepared by various synthetic conditions. The physical properties of a resulting polymer. such as solubility, optical property, and electrical property, were monitored as a function of the concentration of an oxidant and a dopant, as well as reaction time. An increase in the molecular weight with reaction time was clearly observed by GPC and the best results in the solubility and conductivity was obtained using methanol and ferric toluenesulfonate as a solvent and an oxidant, respectively. In chloroform solvent, the solubility reached up to > 90 % and the conductivity of the cast film reached 1.85 S/cm.

Photoluminescence and Electroluminescence from Polymer-Like Organic Thin Films Deposited by Plasma-Enhanced Chemical Vapor Deposition Using Para-Xylene as Precursor

Photoluminescence (PL) and electroluminescence (EL) were observed from the polymer-like organic thin films (POTFs) deposited by plasma-enhanced chemical vapor deposition (PECVD) using p-xylene as the precursor. Absorption and PL spectra suggested that the film includes visible-light-luminescing species. The PL spectrum had a peak around 460 nm. Current-voltage (I-V) and luminescence-voltage (L-V) were measured from the aluminum/POTF/indium-tin-oxide light-emitting diode (LED). L-V curve follows the I-V curve showing a turn-on voltage of ~ 2.5 V. The EL spectrum from the LED was similar to the PL spectrum.

Electrophilic attack of alkyl halide at the cyanide nitrogen in trans-[Fe(H)(CN)(dppe)2]: preparation, structure, and properties of trans-[Fe(H)(CNR)(dppe)2]X (dppe=Ph2PCH2CH2PPh2; R=Me, Et, Pr, i-Pr, n-Bu, CH2CH2Br, CH2CH2CH2I, CH2CHCH2, CH2CCH; X=Br, I)

Abstract Compound trans -[FeH(CN)(dppe) 2 ] ( 1 ) reacted with alkyl iodides or alkyl bromides to give Fe(II)–organic isocyanide complexes of the type trans -[FeH(CNR)(dppe) 2 ]X [X=I: R=Me ( 2 ), Et ( 3 ), Pr ( 4 ), CH 2 CH 2 CH 2 I ( 5 ), i -Pr ( 6 ), CH 2 CHCH 2 ( 7 ); X=Br: R=Et ( 8 ), Pr ( 9 ), n -Bu ( 10 ), CH 2 CH 2 Br ( 11 ), CH 2 CHCH 2 ( 12 ), CH 2 CCH ( 13 )]. Compound 1 reacted with BF 3 to give a Lewis acid–base adduct, trans -[FeH(CN→BF 3 )(dppe) 2 ]. Compounds 5 and 13 were characterized structurally by X-ray diffraction, in which the hydride ligand appears to be involved in the dihydrogen bonding, MH⋯HC.

Solution-processed yolk–shell-shaped WO3/BiVO4 heterojunction photoelectrodes for efficient solar water splitting

The WO3/BiVO4 heterojunction is regarded as one of the most promising photoanode materials for photoelectrochemical (PEC) water splitting. To improve the solar water splitting efficiency, maximizing the solar light absorption efficiency in a photoelectrode is still a critical issue. Here, to achieve the aforementioned need, we designed and fabricated a WO3 film consisting of yolk–shell structured nanoparticles via solution processing. A thin BiVO4 layer with a smaller bandgap was coated onto the surface and inside the WO3 shells, providing a rationally designed inner space between the particles and the shell for better electrolyte accessibility. The yolk–shell-shaped PEC photoanode not only induces efficient light absorption but also plays an important role in electron collection from BiVO4 due to an enlarged contact area. The structure–PEC performance relationship was studied by combining ultraviolet-visible (UV-vis) absorption spectroscopy with a specular and diffuse reflectance technique, which illustrates that the yolk–shell morphology has a superior light absorption ability than conventional hollow or dense film structures. The pure yolk–shell (Y-WO3/BiVO4) photoanode possessed a photocurrent density of 2.3 mA cm−2 and achieved a highest value of ∼5.0 mA cm−2 after adding a Fe–Ni co-catalyst at a bias of 1.23 V vs. RHE under AM 1.5 illumination (100 mW cm−2).

Preparation of Conducting Polymer/Metal Nanocomposites

This study was primarily focused on the preparation and characterization of conducting polymer/metal nanocomposites. Poly(3,4-ethylenedithiathiophene) was prepared onto ITO electrodes as thin film shapes by electrochemical polymerization and reduced with constant potential. When the polymer films were doped with K2PtCl6 solution, they were easily get oxidized due to the concurrent reduction of Pt(IV) to Pt(0). This procedure ended up with the formation of polymer/metal composites. In-situ spectroelectrochemistry was used to investigate the composite formation processes. The final composites were indentified with SEM and EDAX. Catalytic decomposition of methanol on these composite electrodes was observed by using cyclic voltammetry.

Highly Sensitive and Selective Glucose Sensor Realized by Conducting Polymer Modified Nanoporous PtZn Alloy Electrode

Platinum is a well known element which shows a significant electrocatalytic activity in many important applications. In glucose sensor, because of the poisoning effect of reaction intermediates and the low surface area, the electrocatalytic activity towards the glucose oxidation is low which cause the low sensitivity. So, we fabricate a nanoporous PtZn alloy electrode by deposition-dissolution method. It provides a high active surface and a large enzyme encapsulating space per unit area when it used for an enzymatic glucose sensor. Glucose oxidase was immobilized on the electrode surface by capping with PEDOT composite and PPDA. The composite and PPDA also can exclude the interference ion such as ascorbic acid and uric acid to improve the selectivity. The surface area was determined by cyclic voltametry method and the surface structure and the element were analyzed by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray spectroscopy (EDX), respectively. The sensitivity is . It is a remarkable value with such simply prepared senor has high selectivity.