• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1829-1832
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• 2008

This paper reports a novel gas sensing method by using a thermoelectric device, thermopile in this case, with an embedded tin oxide catalyst. By using a thin catalyst film, the response time and recovery time were remarkably improved. The fabricated gas sensor was characterized through detecting NOx gas with various concentrations.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.365-366
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• 2009

• Journal of the Korean Chemical Society
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• v.56 no.4
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• pp.484-490
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• 2012

The tin (IV) oxide nanoparticles are prepared by controlled precipitation method and calcined at temperatures of $200-600^{\circ}C$. The prepared $SnO_2$ nanoparticles characterized by XRD patterns, TEM image, IR and UV-Vis spectra. The XRD patterns and TEM image show the tetragonal structure and spherical morphology for $SnO_2$ nanoparticles, respectively. The photocatalytic activity of the prepared $SnO_2$ nanoparticles studied in degradation reaction of methylene blue (MB). The results show the size of nanoparticles, band-gap energy and photocatalytic activity of $SnO_2$ depends on the calcinations temperature. The $SnO_2$ nanoparticles calcined at $500^{\circ}C$ indicated the highest photoreactivity. Also, the zero-valent tin (ZVT) nanoparticles with tetragonal structure are prepared by a reducing agent and used as a catalyst in degradation of MB. In basic pH of 11, the degradation >95% of MB at time 150 min obtained at presence of ZVT nanoparticles.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1328_1329
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• 2009

Nano porous indium tin oxide (ITO) powder was synthesized employing a new route sol-gel combustion hybrid method using Ketjen Black as a fuel. The nano porous ITO powder was composed of $SnCl_4$-98.0% and $In(NO_3)_3{\cdot}XH_2O$-99.999%, produce with a $NH_4OH$ with sol-gel method as a catalyst [1,2]. Crystal structures were examined by powder X-ray diffraction (XRD), and those results show shaper intensity peak at $25.6^{\circ}(2{\Theta})$ of $SnO_2$ by increased sintering temperature. A particle morphology as well as crystal size was investigated by scanning electron microscopy(FE-SEM), and the size of the nano porous powder was found to be in the range of 20~30nm. ITO films could controlled by nano porous powder at various sintering temperature in this paper[3,4]. The sol-gel combustion method was offered simple and effective route for the synthesis of nano porous ITO powder[5].

• Journal of information and communication convergence engineering
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• v.7 no.1
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• pp.72-77
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• 2009

Three different procedures for adding Pd compounds to $SnO_2$ particles have been investigated. These processes are: (1) coprecipitation; (2) dried powder impregnation; and (3) calcined powder impregnation. The microstructures of $SnO_2$ particles have been analyzed by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). In the coprecipitaion method, the process does not restrain the growth of $SnO_2$ particles and it forms huge agglomerates. In the dried powder impregnation method, the process restrains the growth of $SnO_2$ particles and the surfaces of the agglomerates have many minute pores. In the calcined powder impregnation method, the process restrains the growth of $SnO_2$ particles further and the agglomerates have a lot more minute pores. The sensitivity ($S=R_{air}/R_{gas}$) of the $SnO_2$ gas sensor made by the calcined powder impregnation process shows the highest value (S = 21.5 at 5350 ppm of $C_3H_8$) and the sensor also indicates the lowest operating temperature of around $410^{\circ}C$. It is believed that the best result is caused by the plenty of minute pores at the surface of the microstructure and by the catalyst Pd that is dispersed at the surface rather than the inside of the agglomerate. Schematic models of Pd distribution in and on the three different $SnO_2$ particles are presented.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1338_1339
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• 2009

Dye-sensitized solar cell (DSC) consists of photo electrode, counter electrode and electrolyte. Photo electrode has titanium oxide layer with dye molecule to create electrons. And counter electrode is made of one layer that has catalytic ability for redox system such as the iodide/triiodide couple. Most DSC researchers use platinum as catalyst on counter electrode because platinum has good catalytic ability and conductivity. Platinum is doped on fluorine-doped tin oxide glass with different methods such as sputtering method, electrochemical method and so on. In this paper, we deposit platinum on counter electrode glass with two methods. One is the radio frequency (RF) sputtering method and the other is the chemical method with heating treatment. Finally, we compare the photovoltaic characteristics of DSCs that are assembled using two different counter electrodes.

• Journal of the Korean Electrochemical Society
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• v.11 no.3
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• pp.141-146
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• 2008

Electrocatalytic activities and stabilities of Pt supported on Sb-doped $SnO_2$ (ATO) were examined for ethanol oxidation reactions. Pt colloidal particles were deposited on ATO nanoparticles (Pt/ATO) and the prepared electrocatalysts were characterized by X-ray diffraction, transmission electron microscopy (TEM), and cyclic voltammetry. Electrochemical activity of the Pt/ATO for ethanol electro-oxidation was compared to those of Pt supported on carbon (Pt/C) and commercial PtRu/C. The activitiy of the Pt/ATO was much higher than those of the Pt/C and commercial PtRu/C. The Pt/ATO exhibited much higher electrochemical stabilities than the Pt/C in 0.5M ${H_2}{SO_4}$ and in 0.5M ${H_2}{SO_4}$/1M ${C_2}{H_5}OH$. According to TEM, the growth rate of Pt particles was lower in the Pt/ATO than it was in the Pt/C. The ATO nanoparticle appears to be a promising support material that promotes electrochemical reactions and stabilizes catalyst particles in direct ethanol fuel cell.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.4
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• pp.91-97
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• 2023

Electrochemical (EC) CO₂ reduction is a promising method to convert CO₂ into valuable hydrocarbon fuels and chemicals ecofriendly. Here, we report on a facile method to synthesize surface-controlled SnO₂/Cu(OH)₂ nanowires (NWs) and its EC reduction of CO₂ to HCOOH and CO. The SnO₂/Cu(OH)₂ NWs (-16 mA/cm²) showed superior electrochemical performance compared to Cu(OH)2 NWs (-6 mA/cm²) at -1.0 V (vs. RHE). SnO₂/Cu(OH)₂ NWs showed the maximum Faradaic efficiency for conversion to HCOOH (58.01 %) and CO (29.72 %). The optimized catalyst exhibits a high C1 Faradaic efficiency stable electrolysis for 2 h in a KHCO₃ electrolyte. This study facilitates the potential for the EC reduction of CO₂ to chemical fuels.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2342-2348
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• 2014

Poly(lactic-co-glycolic acid) (PLGA) were grafted to both ends of Pluronic$^{(R)}$ F68 ($(EO)_{75}(PO)_{30}(EO)_{75}$) triblock copolymer to produce poly{(lactic acid)$_m$-co-(glycolic acid)$_n$}-b-poly(ethylene oxide)$_{75}$-b-poly(propylene oxide)$_{30}$-b-poly(ethylene oxide)$_{75}$-b-poly{(lactic acid)$_m$-co-(glycolic acid)$_n$} (PLGA-F68-PLGA) pentablock copolymers. Molecular weights of PLGA blocks were controlled and five kinds of pentablock copolymers with different PLGA block lengths were synthesized using in-situ ring-opening polymerization of D,L-lactide and glycolide with tin(II) 2-ethylhexanoate ($Sn(Oct)_2$) catalyst. PLGA-F68-PLGA pentablock copolymers were characterized by $^1H$- and $^{13}C$-NMR, GPC, and TGA. The numbers (2m, 2n) of repeating units for lactic acid and glycolic acid inside PLGA segments were obtained as (48, 17), (90, 23), (125, 40), (180, 59), and (246, 64), with $^1H$-NMR measurement. From NMR data, the resultant molecular weights were determined in the range of 12,700-29,700, which were similar to those obtained from GPC. Polydispersity index was increased in the range of 1.32-1.91 as the content of PLGA blocks increased. TG and DTG thermograms showed discrete degradation traces for PLGA and F68 blocks, which indicate the weight fractions of PLGA blocks in pentablock copolymers can be calculated by TG profile and it is possible to remove PLGA block selectively. Hydrodynamic radius and radius of gyration of pentablock copolymer micelle were obtained in the range of 46-68 nm and 31-49 nm, respectively, in very dilute (i.e. 0.005 wt %) aqueous solution of THF:$H_2O$ = 10:90 by volume at $25^{\circ}C$.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.2 s.17
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• pp.81-87
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• 2004

Semiconductor thick film gas sensors based on tin oxide are fabricated and their gas response characteristics are examined for four simulant gases of chemical warfare agent (CWA)s. The sensing materials are prepared in three different sets. 1) The Pt or Pd $(1,\;2,\;3\;wt.\%)$ as catalyst is impregnated in the base material of $SnO_2$ by impregnation method.2) $Al_2O_3\;(0,\;4,\;12,\;20\;wt.\%),\;In_2O_3\;(1,\;2,\;3\;wt.\%),\;WO_3\;(1,\;2,\;3\;wt.\%),\;TiO_2\;(3,\;5,\;10\;wt.\%)$ or $SiO_2\;(3,\;5,\;10\;wt.\%)$ is added to $SnO_2$ by physical ball milling process. 3) ZnO $(1,\;2,\;3,\;4,\;5\;wt.\%)$ or $ZrO_2\;(1,\;3,\;5\;wt.\%)$ is added to $SnO_2$ by co-precipitation method. Surface morphology, particle size, and specific surface area of fabricated sensing films are performed by the SEM, XRD and BET respectively. Response characteristics are examined for simulant gases with temperature in the range 200 to $400^{\circ}C$, with different gas concentrations. These sensors have high sensitivities more than $50\%$ at 500ppb concentration for test gases and also have shown good repetition tests. Four sensing materials are selected with good sensitivity and stability and are fabricated as a sensor array A sensor array Identities among the four simulant gases through the principal component analysis (PCA). High sensitivity is acquired by using the semiconductor thick film gas sensors and four CWA gases are classified by using a sensor array through PCA.