• Journal of the Korean Electrochemical Society
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• v.6 no.2
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• pp.158-160
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• 2003

We have reported to make nanostructured cobalt oxide electrode that have large capacitance over than 400 F/g (specific capacitance) and good cycleability. But, it had serious demerits of low voltage range under 0.5 V and low power density. Therefore, we need to increase voltage range of cobalt oxide electrode. We report here on the electrochemical properties of sol-gel-derived nanoparticulate cobalt xerogel in 1M KOH solution and aqueous polymeric gel electrolyte. In solution electrolyte, cobalt oxide electrode had over 250 F/g capacitance consisted of EDLC and pseudocapacitance. In gel electrolyte, cobalt oxide electrode had around 100 F/g capacitance. This capacitance was only electric double layer capacitance of active surface area. In solution electrolyte, potassium ion as working ion reacted with both of layers easily. However, In gel electrolyte, reacted with only surface-active layer. Itis very hard to reach resistive layer. So, we have studied on pretreatment of electrode to contain working ions easily. We'll report more details.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.93-96
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• 2001

We have reported to make nanostructured cobalt oxide electrode that have large capacitance over than 400F/g (specific capacitance) and good cycleability. But, It had serious demerits of low voltage range under 0.5V and low power density. Therefore, we need to increase voltage range of cobalt oxide electrode. we report here on the electrochemical properties of sol-gel-derived nanoparticulate cobalt xerogel in 1M KOH solution and aqueous polymeric gel electrolyte. In solution electrolyte, cobalt oxide electrode had over than 250F/g capacitance consisted of EDLC and pseudocapacitance. In gel electrolyte, cobalt oxide electrode had around l00F/g capacitance. This capacitance was only surface EDLC. In solution electrolyte, potassium ion as working ion reacted with both of layers easily. However, In gel electrolyte, reacted with only surface-active layer. Its very hard to reach resistive layer. So, we have studied on pretreatment of electrode to contain working ions easily. We'll report more details.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.93-96
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• 2001

We have reported to make nanostructured cobalt oxide electrode that have large capacitance over than 400F/g (specific capacitance) and good cycleability. But, It had serious demerits of low voltage range under 0.5V and low power density. Therefore, we need to increase voltage range of cobalt oxide electrode. we report here on the electrochemical properties of sol-gel-derived nanoparticulate cobalt xerogel in 1M KOH solution and aqueous polymeric gel electrolyte. In solution electrolyte, cobalt oxide electrode had over than 250F/g capacitance consisted of EDLC and pseudocapacitance. In gel electrolyte, cobalt oxide electrode had around 100F/g capacitance. This capacitance was only surface EDLC. In solution electrolyte, potassium ion as working ion reacted with both of layers easily. However, In gel electrolyte, reacted with only surface-active layer. Its very hard to reach resistive layer. So, e have studied on pretretmetn of electrode to contain working ions easily. We'll report more details.

• Journal of Electrochemical Science and Technology
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• v.2 no.3
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• pp.174-179
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• 2011

The mesoscopic $Sb_2S_3$-sensitized photoelectrochemical solar cells using cobalt redox electrolyte exhibit nonlinear behavior of power conversion efficiency with illuminated sun intensity. From the measurement of bulk diffusion and electrochemical impedance spectroscopy studies, we suggest that the nonlinearity of device performance with illuminated sun intensity is attributed not to the slow bulk diffusion problem of cobalt electrolyte but to the limited mass transport in narrowed pore volume in mesoscopic $TiO_2$ electrode.

• Corrosion Science and Technology
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• v.19 no.1
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• pp.8-15
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• 2020

In this paper, the efficiency and the inhibition mechanisms of cobalt salts (cobalt nitrate and cobalt-exchange silica Co/Si) for the corrosion protection of AA2024 were investigated in a neutral aqueous solution by using the electrochemical impedance spectroscopy (EIS) and polarization curves. The experimental measurements suggest that cobalt cation plays a role as a cathodic inhibitor. The efficiency of cobalt cation was important at the concentration range from 0.001 to 0.01 M. The formation of precipitates of oxides/hydroxides of cobalt on the surface at low inhibitor concentration was confirmed by the Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy (SEM/EDS) analysis. EIS measurements were also conducted for the AA2024 surface covered by water-based epoxy coating comprising Co/Si salt. The results obtained from exposure in the electrolyte demonstrated the improvement of the barrier and inhibition properties of the coating exposed in the electrolyte solution for a lengthy time. The SEM/EDS analysis in artificial scribes of the coating after salt spray testing revealed the release of cobalt cations in the coating defect to induce the barrier layer on the exposed AA2024 substrate.

• Current Photovoltaic Research
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• v.2 no.1
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• pp.18-27
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• 2014

Dye-sensitized solar cells (DSSCs), developed two decades ago, are considered to be an attractive technology among various photovoltaic devices because of their low cost, accessible dye chemistry, ease of fabrication, high power conversion efficiency, and environmentally friendly nature. A typical DSSCs consists of a dye-coated $TiO_2$ photoanode, a redox electrolyte, and a platinum (Pt)-coated fluorine-doped tin oxide (FTO) counter electrode. Among them, redox electrolytes have proven to be extremely important in improving the performance of DSSCs. Due to many drawbacks of iodide electrolytes, many research groups have paid more attention to seeking other alternative electrolyte systems. With regard to this, one-electron outer sphere redox shuttles based on cobalt complexes have shown promising results: In 2014, porphyrin dye (SM315) with the cobalt (II/III) redox couple exhibited a power conversion efficiency of 13% in DSSCs. In this review, we will provide an overview and perspectives of cobalt redox electrolytes in DSSCs.

• Korean Journal of Materials Research
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• v.24 no.6
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• pp.319-325
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• 2014

Cobalt nano-rods were fabricated using a template-free electrochemical-deposition process. The structure of cobalt electro-deposits strongly depends on the electrolyte composition and on the density of the applied current. In particular, as the content of boric acid increased in the electrolyte, deposits of semi-spherical nuclei formed, and then grew into one-dimensional nano-rods. From analysis of the electro-deposits created under the conditions of continuous and pulsed current, it is suggested that the distribution of the active species around the electrode/electrolyte interface, and their transport, might be an important factor affecting the shape of the deposits. When transport of the active species was suppressed by lowering the deposition temperature, more of the well-defined nano-rod structures were obtained. The optimal conditions for the preparation of well-defined nano-rods were determined by observing the morphologies resulting from different deposition conditions. The maximum height of the cobalt nano-rods created in this work was $1{\mu}m$ and it had a diameter of 200 nm. Structural analysis proved that the nano-rods have preferred orientations of (111).

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.927-930
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• 2013

We developed an electroplating process of cobalt nanowires of which line-widths were between 70 and 200 nm. The plating electrolyte was made of $CoSO_4$ and an organic additive, dimethyldithiocarbamic acid ester sodium salt (DAESA). DAESA in plating electrolytes had an accelerating effect and reduced the surface roughness of plated cobalt thin films. We obtained void-free cobalt nanowires when the plating current density was 6.25 mA/$cm^2$ and DAESA concentration was 1 mL/L.

• Korean Journal of Materials Research
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• v.26 no.8
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• pp.401-405
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• 2016

The cobalt silicides were investigated for employment as a catalytic layer for a DSSC. Using an E-gun evaporation process, we prepared a sample of 100 nm-thick cobalt on a p-type Si (100) wafer. To form cobalt silicides, the samples were annealed at temperatures of $300^{\circ}C$, $500^{\circ}C$, and $700^{\circ}C$ for 30 minutes in a vacuum. Four-point probe, XRD, FE-SEM, and CV analyses were used to determine the sheet resistance, phase, microstructure, and catalytic activity of the cobalt silicides. To confirm the corrosion stability, we also checked the microstructure change of the cobalt silicides after dipping into iodide electrolyte. Through the sheet resistance and XRD results, we determined that $Co_2Si$, CoSi, and $CoSi_2$ were formed successfully by annealing at $300^{\circ}C$, $500^{\circ}C$, and $700^{\circ}C$, respectively. The microstructure analysis results showed that all the cobalt silicides were formed uniformly, and CoSi and $CoSi_2$ layers were very stable even after dipping in the iodide electrolyte. The CV result showed that CoSi and $CoSi_2$ exhibit catalytic activities 67 % and 54 % that of Pt. Our results for $Co_2Si$, CoSi, and $CoSi_2$ revealed that CoSi and $CoSi_2$ could be employed as catalyst for a DSSC.

• Journal of Magnetics
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• v.22 no.2
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• pp.175-180
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• 2017

CoNi alloy films prepared from electrolytes with various concentrations of cobalt ions were studied in the paper. Influences of different cobalt ions concentrations on electrochemistry processes, components, microstructures, surface morphologies and magnetic properties of CoNi films were investigated. It was found that CoNi film plating was a kind of anomalous codeposition process. The percentage of cobalt content in CoNi films was higher than that of in the electrolyte. Moreover, with the rise of cobalt ions concentrations, the percentage of cobalt content in the samples increased gradually. CoNi films possessed crystal structures with four stronger diffraction peaks. However, CoNi films prepared from bath with higher cobalt ions possessed hcp structures which contributed to dendrite structures resulting in the increase of coercivity.