• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.2
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• pp.77-82
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• 2022

Recently, research on the development of low-cost/high-efficiency water electrolysis catalysts to replace noble metal catalysts is being actively conducted. Since overvoltage reduces the overall efficiency of the water splitting device, lowering the overvoltage of the oxygen evolution reaction (OER) is the most important task in order to generate hydrogen more efficiently. Currently, noble metal catalysts show excellent characteristics in OER performance, but they are experiencing great difficulties in commercialization due to their high price and efficiency limitations due to low reactivity. In this study, a water electrolysis catalyst Ni-MWCNT was prepared by successfully doping Ni into the MWCNTs structure through the pulsed laser ablation in liquid (PLAL) process. High resolution-transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS) were performed for the structure and chemical composition of the synthesized Ni-MWCNT. Catalytic oxygen evolution reaction evaluation was performed by linear sweep voltammetry (LSV) overvoltage characteristics, Tafel slope, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and Chronoamperometry (CA) was used for measurement.

• Journal of the Korean Chemical Society
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• v.33 no.2
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• pp.215-224
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• 1989

Electrochemical reductions of $trans-[Co(en)_2X_2](ClO_4)_n$ (where X is cyanide, nitrite, ammonia, and isothiocyanate) were investigated by cyclic voltammetry and polarography at mercury and glassy carbon electrode. $trans-[Co(en)_2(CN)_2]ClO_4$ was reduced to Co(II) complex followed by adsorption to the mercury electrode. Cyanide ion was not released from the reduced Co(II) complex but the cyanide and (en) were released after the reduction to metallic cobalt. The other complexes except $trans-[Co(en)_2(CN)_2]ClO_4$ were reduced to cobalt(II) complexes followed by release of monodendate ligand, and (en) was released at the reduction step to metallic cobalt. $trans-[Co(en)_2(NO_2)_2]ClO_4$ was reduced to cobalt(Ⅱ) complex, and $NO_2^-$ ion was released followed by electroreduction through ECE mechanism at pH 2. On glassy carbon electrode, all complexes of Co(III) were reduced to Co(II) complexes with irreversible one-electron diffusion controlled reaction in which (en) was not released at this step. Increasing absorption wave number of complexes caused to negative shift of peak potential.

• Journal of the Korean Chemical Society
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• v.33 no.5
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• pp.484-495
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• 1989

Reactions of $(Et_4N)_2[MoOCl_5]$ with multidentate ligands containing nitrogen or/and oxygen donor atom (EDTA, DTPA, IDA, CyDTA, OX) produce a series of binuclear molybdate (V) complexes. The prepared Mo (V) complexes has been identified by Elemental Analysis, Infrared Spectra, Proton Magnetic Resonance Spectra, and Electronic Spectra. The electrochemical reduction mechanism has been studied by Cyclic voltammetry, Controlled Potential Coulometry, and Spectrophotometry in pH 3.571-10.375 acetate, borate, phosphate/sodium hydroxide, phosphate, ammonium/ammonia buffers. The cyclic voltammogram of the Mo-EDTA, DTPA, IDA, CyDTA complexes at pH < ca. 6.00 have shown two reduction waves. The first reduction wave shows two electron process and the second reduction wave shows two electron process. The cyclic voltammogram of the Mo-EDTA, DTPA, IDA, CyDTA complexes at pH < ca. 8.00 has shown one reduction wave. This reduction wave show four electron process. The cyclic voltammogram of the Mo-OX complex at pH < ca. 7.2 has shown one reduction wave. This reduction wave show four electron process.