• Korean Journal of Materials Research
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• v.27 no.2
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• pp.94-99
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• 2017

Dinickel-silicide $(Ni_2Si)/glass$ was employed as a counter electrode for a dye-sensitized solar cell (DSSC) device. $Ni_2Si$ was formed by rapid thermal annealing (RTA) at $700^{\circ}C$ for 15 seconds of a 50 nm-Ni/50 nm-Si/glass structure. For comparison, $Ni_2Si$ on quartz was also prepared through conventional electric furnace annealing (CEA) at $800^{\circ}C$ for 30 minutes. XRD, XPS, and EDS line scanning of TEM were used to confirm the formation of $Ni_2Si$. TEM and CV were employed to confirm the microstructure and catalytic activity. Photovoltaic properties were examined using a solar simulator and potentiostat. XRD, XPS, and EDS line scanning results showed that both CEA and RTA successfully led to tne formation of nano $thick-Ni_2Si$ phase. The catalytic activity of $CEA-Ni_2Si$ and $RTA-Ni_2Si$ with respect to Pt were 68 % and 56 %. Energy conversion efficiencies (ECEs) of DSSCs with $CEA-Ni_2Si$ and $RTA-Ni_2Si$catalysts were 3.66 % and 3.16 %, respectively. Our results imply that nano-thick $Ni_2Si$ may be used to replace Pt as a reduction catalytic layer for a DSSCs. Moreover, we show that nano-thick $Ni_2Si$ can be made available on a low-cost glass substrate via the RTA process.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.101-101
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• 2015

Photoelectrochemical water splitting is considered as a promising method of transforming solar energy into chemical energy stored in the type of hydrogen. An n-type $WO_3$ semiconductor is one of the most promising photoanodes for hydrogen production from water splitting. Films annealed at lower temperatures consisted of amorphous, whereas films annealed above $500^{\circ}C$ comprised solely of monoclinic $WO_3$. In this study, we observed photoactivity of $WO_3$ as increasing thickness of $WO_3$. And it shows good photoacivity as thickness increases. Also we tried to improve photoactivity through surface modification and bulk modification by using hydrogen treatment and conducting polymer. The photocurrent was measured in potentiostatic method with the three electrode system. A Pt wire and Ag / AgCl electrode were used as the counter electrode and the reference electrode, respectively. photocurrent-time (I-T) curve was measured at a bias potential of 0.79 V.

• Korean Journal of Materials Research
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• v.24 no.10
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• pp.565-571
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• 2014

Nitrogen-doped ZnO nanoparticle-carbon nanofiber composites were prepared using electrospinning. As the relative amounts of N-doped ZnO nanoparticles in the composites were controlled to levels of 3.4, 9.6, and 13.8 wt%, the morphological, structural, and chemical properties of the composites were characterized by means of field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). In particular, the carbon nanofiber composites containing 13.8 wt% N-doped ZnO nanoparticles exhibited superior catalytic properties, making them suitable for use as counter electrodes in dye-sensitized solar cells (DSSCs). This result can be attributed to the enhanced surface roughness of the composites, which offers sites for $I_3{^-}$ ion reductions and the formation of Zn3N2 phases that facilitate electron transfer. Therefore, DSSCs fabricated with 13.8 wt% N-doped ZnO nanoparticle-carbon nanofiber composites showed high current density ($16.3mA/cm^2$), high fill factor (57.8%), and excellent power-conversion efficiency (6.69%); at the same time, these DSSCs displayed power-conversion efficiency almost identical to that of DSSCs fabricated with a pure Pt counter electrode (6.57%).

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.925-928
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• 2014

A dye-sensitized solar cell (DSSC) was fabricated with a nanocrystalline $TiO_2$ film electrode on FTO glass, N719 dye, electrolytes (or $CsSnI_3$), and counter Pt electrode by incorporating it with single-walled carbon nanotubes (SWNTs). SWNTs were combined with $TiO_2$ film, $CsSnI_3$, Pt electrode, separately, and the SWNT-containing cell was compared with a pristine cell in cell performance. We also examined the performance change by pressing $TiO_2$ film, during cell fabrication, inside a high pressure chamber. Mostly, the change of conversion efficiency was compared for each cell, and an atomic force microscopy data were suggested to explain our results.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.4
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• pp.337-342
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• 2022

In this study, a water electrolysis was studied to investigate the effect of ammonia on current density and H2 gas production. A H type cell with three electrodes was used and KOH solution was used as electrolyte. The conventional platinum foil was used for working electrode, whereas nickel foam was used for counter electrode. CV experiment was performed to see the activity of ammonia oxidation reaction. In addition, CP experiment was done to examine the dependence of Faraday efficiency of hydrogen on current density and NH3 concentration. The CV result shows the 0.5M NH3 concentration required for highest current density and reliable operation. The CP result shows the increased current density leads to higher H2 generation. The higher H2 production and subsequent energy efficiency was observed for 0.5M NH3 using a Pt/13%Rh coil for a cathode as compared to those in water electrolysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.584-587
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• 2011

In this work, the $TiO_2$ and $SnO_2$ thin films as blocking layers were coated directly onto the metal-mesh electrode surface to prevent unnecessary inflow of back-transfer electrons from the electrolyte ($I^-/I_3^-$) to the metal-mesh electrode. The DSCs were fabricated with working electrode of SUS mesh coated with blocking $TiO_2$ and $SnO_2$ layers, dye-attached mesoporous $TiO_2$ film, gel electrolyte and counter electrode of Pt-deposited F:$SnO_2$. From the experimental result, it was ascertained that the efficiency of metal electrode coated with $TiO_2$ by Dip-coating was superior to that of metal electrode coated with $SnO_2$ by Dip-coating and screen printing with the results of experiments. The photo-current conversion efficiency of the cell obtained from optimum fabrication condition was 3% ($V_{oc}$=0.61V, $J_{sc}$=11.64 mA/$cm^2$, ff=0.64) under AM1.5, 100 mW/$cm^2$ illumination.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1529_1530
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• 2009

The process conditions for fabricating p-type silicon pillars were optimized by controlling current density, bath temperature. To get best process flexibility for pillar arrays formation, three factors affecting pillar formation were changed. First, the solution bath was designed to keep constant temperature during the experiment irrespective of external temperature. Second, the counter Pt electrode was changed from rod type to mesh to obtain uniform distribution of current density. Third, Cr-Cu alloy electrode instead of Cu was used to increase electrode current density.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1379-1385
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• 2018

The hand held voltammetry systems searched diabetic assay using glucose sensor of fluorine nafion doped carbon nanotube electrode (FCNE). An inexpensive graphite carbon pencil was used as an Ag/AgCl reference and Pt counter electrode. Upon combining and using three electrode systems, optimum square wave (SW) stripping results were attained to 1.0-9.0 ug/L with 8 points. Statistic RSD precision was of 6.02 % with n=15 in 0.1 mg/L glucose. After a total of 200 second accumulation times, analytical detection limit of 0.8 ug/L was obtained. This developed technique was applied to urine samples from diabetic patients urine for fluid analysis, it was determined that the sensor can be used with a diagnostics in the ex vivo of live cells and non treated biological fluid.

• Korean Journal of Materials Research
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• v.26 no.11
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• pp.649-655
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• 2016

Ni nanoparticles (NPs)-graphitic carbon nanofiber (GCNF) composites were fabricated using an electrospinning method. The amounts of Ni precursor used as catalyst for the catalytic graphitization were controlled at 0, 2, 5, and 8 wt% to improve the photovoltaic performances of the nanoparticles and make them suitable for use as counter electrodes for dye-sensitized solar cells (DSSCs). As a result, Ni NPs-GCNF composites that were fabricated with 8 wt% Ni precursors showed a high circuit voltage (0.73 V), high photocurrent density ($14.26mA/cm^2$), and superb power-conversion efficiency (6.72%) when compared to those characteristics of other samples. These performance improvements can be attributed to the reduced charge transport resistance that results from the synergetic effect of the superior catalytic activity of Ni NPs and the efficient charge transfer due to the formation of GCNF with high electrical conductivity. Thus, Ni NPs-GCNF composites may be used as promising counter electrodes in DSSCs.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.100-106
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• 2009

A novel 8 V DC power source with an external series-parallel connection of 50 Dye-sensitized Solar Cells (DSCs) has been proposed. One DSC has the optimized length to width ratio of $5.2{\times}2.6\;cm$ and an active area $8\;cm^2$ ($4.62{\times}1.73\;cm$) which attained a conversion efficiency of 4.02%. From the electrochemical impedance spectroscopic analysis, it was found that the resistance elements related to the Pt electrode and electrolyte interface behave like that of diode and the series resistance corresponds to the sum of the other resistance elements. Surface morphology and sheet resistance of Pt counter electrode did not degrade the performance of the cell. This novel 8V-0.33A DC power source shows stable performance with an energy conversion efficiency of 4.24% under 1 sun illumination (AM 1.5, Pin of $100\;mW/cm^2$).