• Title/Summary/Keyword: hydrogen sensor$WO_3$

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Fabrication of an Optical Hydrogen Sensor Based on 3C-SiC Photovoltaic Effect and Its Characteristics (3C-SiC 광기전 특성 기반 광학식 수소센서의 제작과 그 특성)

  • Kim, Kang-San;Chung, Gwiy-Sang
    • Journal of Sensor Science and Technology
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    • v.21 no.4
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    • pp.283-286
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    • 2012
  • This paper presents the optical hydrogen sensor based on transparent 3C-SiC membrane and photovoltaic effect. Gasochromic materials of Pd and Pd/$WO_3$ were deposited by sputter on 3C-SiC membrane for gas sensing area. Gasochromic materials change to transparency by exposure to hydrogen. The variations of light intensity by hydrogen generate the photovoltaic of P-N junction between N-type 3C-SiC and P-type Si. Single layer of Pd shows higher photovoltaic compared with Pd/$WO_3$. However, phase transition from ${\alpha}$ to ${\beta}$ is shown at 6 %. Pd/$WO_3$ structure show the more linear response to hydrogen range of 2 % ~10 %. Also, almost 2 times fast response and recovery characteristics are shown at Pd/$WO_3$. These fast performances are come from the fact that Pd promoted the chemical reaction between hydrogen and $WO_3$.

Characteristics of Pd-doped WO3 thin film for hydrogen gas sensor (수소 센서용 Pd 첨가한 WO3 박막의 특성)

  • Kim, Gwang-Ho;Choi, Gwang-Pyo;Kwon, Yong;Park, Jin-Seong
    • Journal of Sensor Science and Technology
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    • v.15 no.2
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    • pp.120-126
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    • 2006
  • Physicochemical and electrical properties for hydrogen gas sensors based on Pd-deposited $WO_3$ thin films were investigated as a function of Pd thickness, annealing temperature, and operating temperature. $WO_3$ thin films were deposited on an insulating material by thermal evaporator. XRD, FE-SEM, AFM, and XPS were used to evaluate the crystal structure, microstructure, surface roughness, and chemical property, respectively. The deposited films were grown $WO_3$ polycrystalline with rhombohedral structure after annealing at $500^{\circ}C$. The addition effect of Pd is not the crystallinity but the suppression of grain growth of $WO_3$. Pd was scattered an isolated small spherical grain on $WO_3$ thin film after annealing at $500^{\circ}C$ and it was agglomerated as an irregular large grain or diffused into $WO_3$ after annealing at $600^{\circ}C$. 2 nm Pd-deposited $WO_3$ thin films operated at $250^{\circ}C$ showed good response and recovery property.

Highly Selective and Sensitive Detection of Acetone by ZnWO4-WO3 Hetero-composite Spheres

  • Ki Beom Kim;Myung Sung Sohn;Seong-Young Jeong
    • Journal of Sensor Science and Technology
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    • v.33 no.5
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    • pp.237-241
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    • 2024
  • ZnWO4-WO3 hetero-composite microspheres were prepared by ultrasonic spray pyrolysis of a solution containing Zn and W cations, followed by heat treatment at 600℃. The gas-sensing characteristics of 5 at% of Zn-added WO3 (5Zn-WO3; ZnWO4-WO3 hetero-composite) microspheres to 1 ppm acetone, ethanol, 20 ppm hydrogen (H2), 5 ppm carbon monoxide (CO), 25 ppb toluene, and 5 ppm ammonia (NH3) were measured at 325-400℃ under 80% relative humidity (RH). The sensor using 5Zn-WO3 microspheres exhibited highly selective and sensitive gas-sensing properties to acetone at 375℃ even under high humidity conditions. These superior gas-sensing properties were attributed to the increased resistance (electronic sensitization) through n-n heterojunction formation between WO3 and ZnWO4 phases and the acidic property of WO3, which exhibited a low gas response to interfering ethanol gas. The superior acetone gas-sensing characteristics of the 5Zn-WO3 sensor can be utilized in breath acetone analyzers for rapid, real-time ketogenic diet monitoring.

Optical Hydrogen Sensor Based on Gasochromic $RuO_2{\cdot}xH_2O$ Thin Film ($RuO_2{\cdot}xH_2O$ 박막의 가스채색 현상을 이용한 수소검지 광센서)

  • Cheong, Hyeon-Sik;Jo, Hyun-Chol;Kim, Kyung-Moon
    • Journal of Hydrogen and New Energy
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    • v.16 no.1
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    • pp.9-16
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    • 2005
  • We studied the electrochromic properties of hydrated amorphous ruthenium oxide ($RuO_2{\cdot}xH_2O$) thin films using in-situ Raman spectroscopy during electrochemical charging/discharging cycles. We have found that the principal effect of hydrogen insertion into $RuO_2{\cdot}xH_2O$ is reduction of $Ru^{4+}\;to\;Ru^{3+}$, and not formation of new bonds involving hydrogen. We compared the changes in the Raman spectrum of a gasochromic $Pd/RuO_2{\cdot}xH_2O$ film as it is exposed to hydrogen gas with that of electrochemical hydrogen insertion. We tested the changes in the optical transmission of the $Pd/RuO_2{\cdot}xH_2O$ film when exposed to hydrogen gas.