• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.15 no.7
• /
• pp.615-620
• /
• 2002

In the case of immobilizing of glucose oxidase into polypyrrole (PPy) using electrosynthesis, the glucose oxidise (GOx) forms a coordinate bond with the polymers backbone. However, because of intrinsic insulation and net-chain of the enzyme, the charge transfer and mass transport are obstructed during the film growth. Therefore, the film growth is dull. We synthesized enzyme electrodes by electropolymerization added some organic solvent, such as ethanol and tetrahydrofuran (THF). The formative seeds of film growth was delayed by adding ethanol. The delay was induced by radical transfer between ethanol and pyrrole monomer. The radical transfer reactions shared the contribution of dopants between electrolyte anion and GOx polyanion. This led to increase amount of immobilized the enzyme in PPy. For the UV absorption spectra of synthetic solution before synthesis and after, in the case of ethanol added, the optical density was slightly decreased for the GOx peaks. It suggests amount of GOx in the solution was decreased and amount of GOx in the film was increased.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.15 no.7
• /
• pp.621-626
• /
• 2002

In the case of immobilizing of glucose oxidase (GOx) in polypyrrole (PPy) conducting polymer using electrosynthesis, the GOx obstructs charge transfer and mass transport during the film growth. This may lead to short chained polymer and/or make charge-coupling weak between the GOx and the backbone of the PPy. That is mainly due to insulating property and net chain of the GOx. Since being the case, it is useless to increase in amount of GOx mere than reasonable in the synthetic solution. We improved the amount of immobilized GOx into the PPy by adding a little ethanol in the synthetic solution without any more amount of GOx in the solution. We electrochemically analyzed an improvement in the immobilizing event. For the glucose sensing, when ethanol was added by 0.1 mol $dm^{-3}$ in the synthetic solution, the Michaelis constant of the resulting enzyme electrode was about 32 mmol $dm^{-3}$ and maximum current was about $146\mu A$.

• Proceedings of the KIEE Conference
• /
• 1999.11d
• /
• pp.984-986
• /
• 1999

In the case of immobilizing of glucose oxidase in organic polymer using electrosynthesis, the glucose oxidase obstructs charge transfer and mass transport during the film growth. This may lead to short chained polymer and make charge-coupling weak between the glucose oxidase and the backbone of the polymer. That is mainly due to insulating property and net chain of the glucose oxidase. Such being the case, it is useless to increase in amount of glucose oxidase more than reasonable in the synthetic solution. We establish by means of qualitative analysis that amount of immobilized glucose oxidase can be improved by adding a hole ethyl alcohol in the synthetic solution. As ethyl alcohol was added by 0.1mol $dm^{-3}$ in the synthetic solution, the faradic impedance of resultant electrode was increased about five times as much as the case of ethyl alcohol free in the solution, and mass transport was limited more than over. That is due to insulating property and net chain of the glucose oxidase. Moreover, in ultraviolet spectra of the synthetic solution, the adsorption peak at 285nm corresponding to glucose oxidase was decreased. It suggests increase in amount of immobilized glucose oxidase.

• Journal of Electrochemical Science and Technology
• /
• v.4 no.1
• /
• pp.1-18
• /
• 2013

Gallium is an important element in the production of a variety of compound semiconductors for optoelectronic devices. Gallium has a low melting point and is easily oxidized to give oxides of different compositions that depend on the conditions of solutions containing Ga. Gallium electrode reaction is highly irreversible in acidic media at the dropping mercury electrode. The passive film on a gallium surface is formed during anodic oxidation of gallium metal in alkaline media. Besides, some results in published reports have not been consistent and reproducible. An increase in the demand of intermetallic compounds and semiconductors containing gallium gives rise to studies on electrosynthesis of them and an increase of gallium concentration in the environment with various application of gallium causes the development of electroanalysis tools of Ga. It is required to understand the electrochemistry of Ga and to predict the electrochemical behavior of Ga to meet these needs. Any review papers related to the electrochemistry of gallium have not been published since 1978, when the review on the subject was published by Popova et al. In this study, the redox behavior, anodic oxidation, and electrodeposition of gallium, and trace determination of gallium by stripping voltammetries will be reviewed.

• Journal of Electrochemical Science and Technology
• /
• v.14 no.2
• /
• pp.105-119
• /
• 2023

The electrochemical chlorine evolution reaction (CER) is an important electrochemical reaction and has been widely used in chlor-alkali electrolysis, on-site generation of ClO^-, and Cl₂-mediated electrosynthesis. Although precious metal-based mixed metal oxides (MMOs) have been used as CER catalysts for more than half a century, they intrinsically suffer from a selectivity problem between the CER and parasitic oxygen evolution reaction (OER). Hence, the design of selective CER electrocatalysts is critically important. In this review, we provide an overview of the fundamental issues related to the electrocatalysis of the CER and design strategies for selective CER electrocatalysts. We present experimental and theoretical methods for assessing the active sites of MMO catalysts and the origin of the scaling relationship between the CER and the OER. We discuss kinetic analysis methods to understand the kinetics and mechanisms of CER. Next, we summarize the design strategies for new CER electrocatalysts that can enhance the reactivity of MMO-based catalysts and overcome their scaling relationship, which include the doping of MMO catalysts with foreign metals and the development of non-precious metal-based catalysts and atomically dispersed metal catalysts.

• New & Renewable Energy
• /
• v.16 no.1
• /
• pp.58-67
• /
• 2020

Microbial electrosynthesis has recently been considered a potentially sustainable biotechnology for converting carbon dioxide (CO₂) into valuable biochemicals. In this study, bioelectrochemical acetate production from CO₂ was studied in an H-type two-chambered reactor system with an anaerobic microbial consortium. Metal-rich mud flat was used as the inoculum and incubated electrochemically for 90 days under a cathode potential of -1.1 V (vs. Ag/AgCl). Four consecutive batch cultivations resulted in a high acetate concentration and productivity of 93 mmol/L and 7.35 mmol/L/day, respectively. The maximal coulombic efficiency (rate of recovered acetate from supplied electrons) was estimated to be 64%. Cyclic voltammetry showed a characteristic reduction peak at -0.2~-0.4 V, implying reductive acetate generation on the cathode electrode. Furthermore, several electroactive acetate-producing microorganisms were identified based on denaturing- gradient-gel-electrophoresis (DGGE) and 16S rRNA sequence analyses. These results suggest that the mud flat can be used effectively as a microbial source for bioelectrochemical CO₂ conversion.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.05b
• /
• pp.316-319
• /
• 2000

In the case of immobilizing of glucose oxidase into polypyrrole (PPy) using electrosynthesis, the glucose oxidase (GOx) forms a coordinate bond with the polymer's backbone. However, because of intrinsic insulation and net-chain of the enzyme, the charge transfer and mass transport are obstructed during the film growth. Therefore, the film growth is dull. We synthesized the enzyme electrode by electropolymerization added some organic solvent, A formative seeds of film growth is delayed by adding the solvent. The delay is induced by radical transfer between the solvent and pyrrole monomer. In the case of adding ethanol, the radical transfer shares the contribution of dopant between electrolyte anion and GOx polyanion. This may lead to increase amount of immobilized the enzyme in ppy. However, adding tetrahydrofuran (THF), the radical transfer is more brisk, resulting in short chained polymer. Therefore, the doping level is lowered and then amount of immobilized of enzyme is decreased. For the UV absorption spectra of synthetic solution before synthesis and after, in the case of ethanol added, the optical density was slightly decreased for the GOx peaks. It suggests amount of GOx in the solution was decreased and amount of GOx in the film was increased. We established qualitatively that amount of immobilization can be improved by adding a little ethanol in the synthetic solution. It is due to radical transfer reaction. The radical transfer shares the contribution of dopant between small and fast electrolyte anion and big and slow GOx polyanion.

• Korean Journal of Materials Research
• /
• v.27 no.3
• /
• pp.137-143
• /
• 2017

Boron-doped diamond (BDD) electrode has an extremely wide potential window in aqueous and non-aqueous electrolytes, very low and stable background current and high resistance to surface fouling due to weak adsorption. These features endow the BDD electrode with potentially wide electrochemical applications, in such areas as wastewater treatment, electrosynthesis and electrochemical sensors. In this study, the characteristics of the BDD electrode were examined by scanning electron microscopy (SEM) and evaluated by accelerated life test. The effects of manufacturing conditions on the BDD electrode were determined and remedies for negative effects were noted in order to improve the electrode lifetime in wastewater treatment. The lifetime of the BDD electrode was influenced by manufacturing conditions, such as surface roughness, seeding method and rate of introduction of gases into the reaction chamber. The results of this study showed that BDD electrodes manufactured using sanding media of different sizes resulted in the most effective electrode lifetime when the particle size of alumina used was from $75{\sim}106{\mu}m$ (#150). Ultrasonic treatment was found to be more effective than polishing treatment in the test of seeding processes. In addition to this, BDD electrodes manufactured by introducing gases at different rates resulted in the most effective electrode lifetime when the introduced gas had a composition of hydrogen gas 94.5 vol.% carbon source gas 1.6 vol.% and boron source gas 3.9 vol.%.

• Applied Chemistry for Engineering
• /
• v.7 no.3
• /
• pp.473-480
• /
• 1996

Synthesis of n-perfluorooctanesulfonyl fluoride(n-PFOSF), which is valuable precursor perfluoro-chemicals, was studied by electrochemical fluorination(ECF). Of prime concern was to investigate the cyclic voltamograms of Ni electrode in anhydrous hydrogen fluoride(AHF) with and without the reactants and to measure fluorine evolution potential. In a batch cell, chronoampherometric electrolysis and various chemical analysis such as GC, GC/MS and IR were used to understand the amphere change of electrode and the reaction paths. Fluorine equilibrium potential was found to be about 2.8V(vs. $Cu/CuF_2$) from the cyclic voltammograms and decay curves of anode potential in AHF. In batch processes, the ECF proceeded in two distinguished steps. The first step proceeded electrochemically and the second one chemically. Under 7V(vs. $Cu/CuF_2$), amount of crude products was proportional to the applied anode potential. Above 7V(vs. $Cu/CuF_2$), it had a hundred percentage with weight ratio of reactants and productivity of PFOSF was almost constant.