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Indirect Electrochemical Oxidation of Phenol by Ce4+, Controlling Surface Insulation of Au Electrode
표명호,문일식 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.6
Indirect electrochemical oxidation of phenol by Ce4+ was investigated in sulfuric acid solutions. It was found that electrode fouling during oxidation of phenol can be controlled by adjusting the time interval (TI) of double potential steps (DPSs). While the electroactivity was greatly decreased after several DPSs of a relatively long TI, repeated DPSs with a short potential pulse showed substantial amounts of electroactivity after a few hundreds or thousands DPS, suggesting that the formation of an insulating layer can be controlled by adjusting a potential program. Effectiveness of the consecutive application of DPSs for phenol decomposition was confirmed by GC-MS.
표명호,Jungsook Joo,Youn Su Jung 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.8
Au was electrolessly deposited on polycarbonate (PC) membranes (0.1 mm pores) at the air/water interface. It was found that the Au nanotube dimension can be controlled by adjusting the plating temperature and the solution composition. Interfacial deposition of Au at relatively low temperatures (4 oC) produced long nanotubes, which run through the whole membrane thickness with small openings. Increase of plating temperatures resulted in the decrease of nanotube lengths and Au film thicknesses. It was also disclosed that the inside-diameter of Au nanotubes can be controlled with negligible variations in length by changing the composition of a plating solution.
조연경,표명호,정규관 한국전기화학회 2010 한국전기화학회지 Vol.13 No.1
New monomers, possessing various alkyl substituents on propylene dioxypyrrole, were synthesized. The monomers could be easily polymerized to produce highly conductive and soluble polymers. The corresponding polymers showed excellent solubility, retaining electrochemical and optical properties of their parent polymer [poly(propylene dioxypyrrole)]. The conductivities of chemically prepared polymers were quite high in a range of 20 and 60 Scm−1. Solubility of the polymer in a common organic solvent was as high as no polymer is deposited on an electrode. The redox potentials of the electrochemically prepared polymers revealed quite stable electroactivity during repeated redox switching up to 500 times. The optoelectrochemistry studies also showed distinct color changes of the polymers upon changing the doping state, indicating strong absorption peaks at 400~600 nm in reduced states and complete bleaching in fully oxidized states.
한수철,김유신,표명호 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.11
A reduced graphene oxide/disodium terephthalate (RGO/DST) composite was prepared via ultrasonic-assisted co-precipitation. The ultrasonication of an azeotropic H2O/acetonitrile solution at elevated temperature induced simultaneous precipitations of RGO and DST with solvent evaporation. RGO/DST, collected before complete evaporation, showed that the DST was in a well-dispersed state between the graphene layers of the RGO, giving the RGO/DST a more densely stacked microstructure. When applied as an anode for sodium ion batteries (SIBs), the RGO/DST revealed an enhancement in Na+-storage capability, relative to composites prepared via simple evaporation (E-RGO/DST) and mechanical mixing (M-RGO/DST). The RGO/DST delivered a reversible capacity of 422 mAh/g at a charge/discharge (C/D) rate of 50 mA/g, in contrast to 368 and 303 mAh/g for E-RGO/DST and M-RGO/DST, respectively. The superiority of the RGO/DST was maintained during repeated cycles. With an increase in the current densities, however, the reversible capability of the RGO/DST was decreased more substantially than that of the M-RGO/DST. Since Na+ diffusivity was greater in the RGO/DST than in the M-RGO/DST, this glitch in the high-rate performance of RGO/DST was considered because of a high level of charge-transfer impedance, in which a dense microstructure hampered the structural change of DST during reduction and oxidation.
Viswanathan S. Saji,표명호 한국물리학회 2010 Current Applied Physics Vol.10 No.3
Poly(ethyl thieno[3,4-b]thiophene-2-carboxylate) (PTTEt), showing near infrared (NIR) absorption was employed as a polymer sensitizer in dye-sensitized solar cell (DSSC). The photovoltaic performance of DSSC was investigated with PTTEt of different molecular weights. Low molecular weight aliphatic diacids were also employed as coadsorbents along with PTTEt. It was revealed that the reduction of polymer molecular weights caused only a slight enhancement in overall power conversion efficiency (η). The species and concentration of coadsorbents, on the other hand, greatly affects η. The best performance with η of ca. 1.5% was obtained when 3,30-dithiodipropionic acid was adsorbed along with PTTEt, indicative of significant improvement of η (ca. 50% increase).
Youn Su Jung,표명호 대한화학회 2008 Bulletin of the Korean Chemical Society Vol.29 No.5
Removal of heavy metal ions (Cd²+ and Zn²+) by electrocoagulation (ECG) was investigated in an acidic condition, which is necessary for re-using or discharging the mediated electrochemical oxidation (MEO) media. Effects of various parameters such as electrolytes, current densities, and electrode materials were examined for a metal-contaminated MEO system using Fe²+/Fe³+ pairs as a mediator. It was found that ECG with Al electrodes is greatly affected by the presence of Fe²+. [Cd²+] and [Zn²+] remain constant until [Fe²+] reaches a certain concentration level (ca. 10 mM). This preferential removal of Fe²+ during ECG with Al electrodes is not alleviated by controlling current densities, potential programs, and solution mixing. ECG with Fe electrodes, on the other hand, resulted in relatively fast removal of Cd²+ and Zn²+ under coexistence of Fe²+, indicative of the different role between Fen+ generated from an electrode and Fe²+ initially present in a solution. When ECG was performed with Fe electrodes until [Fen+] became the same as the concentration of initially present Fe²+, [Cd²+] and [Zn²+] were reduced to one-tenth of the initial concentrations, suggesting the possibility of a continuous use of the medium for a subsequent MEO process.
Eun Gyoung Bae,Yun-Hwa Hwang,표명호 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.4
Nanocomposites consisting of Sn nanoparticles and graphene oxide (GO) were electrophoretically deposited onto Cu current collectors that was used for anodes in Li ion batteries (LIBs). In order to optimize the electrochemical performance of nanocomposites as an anode material by controlling the oxygen functionality, the GO was subjected to O3 treatment prior to electrophoretic deposition (EPD). During thermal reduction of the GO in the nanocomposites, the Sn nanoparticles were reduced in size, along with the formation of SnO and/ or SnO2 at a small fraction, relying on the oxygen functionalities of the GO. The variation in the duration of time for the O3 irradiation resulted in a small change in total oxygen content, but in a significantly different fraction of each functional group in the GO, which influenced the Sn nanoparticle size and the amount of SnO (and/or SnO2). As a result, the EPD films prepared with the GO that possessed the least amount of carboxylic groups (made by treating GO in an O3 environment for 3 h) showed the best performance, when compared with the nanocomposites composed of untreated GO or GO that was O3-treated for a duration of less than 3 h.