DOCSLIB.ORG

Room Temperature Operation of UV Photocatalytic Functionalized Algan/Gan Heterostructure Hydrogen Sensor

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Room Temperature Operation of UV Photocatalytic Functionalized Algan/Gan Heterostructure Hydrogen Sensor nanomaterials Communication Room Temperature Operation of UV Photocatalytic Functionalized AlGaN/GaN Heterostructure Hydrogen Sensor June-Heang Choi 1 , Taehyun Park 2 , Jaehyun Hur 2,* and Ho-Young Cha 1,* 1 School of Electronic and Electrical Engineering, Hongik University, Seoul 04066, Korea; [email protected] 2 Department of Chemical and Biological Engineering, Gachon University, Seongnam 13120, Gyeonggi, Korea; [email protected] * Correspondence: [email protected] (J.H.); [email protected] (H.-Y.C.) Abstract: An AlGaN/GaN heterostructure based hydrogen sensor was fabricated using a dual cata- lyst layer with ZnO-nanoparticles (NPs) atop of Pd catalyst film. The ZnO-NPs were synthesized to have an average diameter of ~10 nm and spin coated on the Pd catalyst layer. Unlike the conventional catalytic reaction, the fabricated sensors exhibited room temperature operation without heating owing to the photocatalytic reaction of the ZnO-NPs with ultraviolet illumination at 280 nm. A sensing response of 25% was achieved for a hydrogen concentration of 4% at room temperature with fast response and recovery times; a response time of 8 s and a recovery time of 11 s. Keywords: AlGaN/GaN; ZnO-nanoparticles; Pd; photocatalyst; hydrogen sensor; ultraviolet Citation: Choi, J.-H.; Park, T.; Hur, J.; 1. Introduction Cha, H.-Y. Room Temperature Hydrogen is presently being studied as an alternative energy source for eco-friendly Operation of UV Photocatalytic renewable energy generation instead of fossil fuels [1,2]. The successful utilization of Functionalized AlGaN/GaN hydrogen requires highly sensitive and reliable safety sensors. For example, hydrogen Heterostructure Hydrogen Sensor. explosions occur at concentrations exceeding 4.65% [3–5]; therefore, the sensor must detect Nanomaterials 2021, 11, 1422. https:// low levels of hydrogen quickly and accurately. doi.org/10.3390/nano11061422 Among various types of sensors, an FET-type sensor with a catalytic gate material has been widely studied due to its compact size and low power consumption. A catalytic Academic Editor: Gabriella Caminati reaction with a target gas changes the surface potential of FET, which in turn modulates the FET current [5–7]. Received: 13 April 2021 Gallium nitride (GaN) has a wide energy bandgap of 3.4 eV [8–13], which results in Accepted: 25 May 2021 a low intrinsic carrier density allowing GaN to maintain its semiconductor properties at Published: 28 May 2021 much temperatures higher than those possible with Si or GaAs. When an AlGaN/GaN heterostructure is formed, a 2-dimensional electron gas (2DEG) channel is created with Publisher’s Note: MDPI stays neutral high mobility at the interface [14–16]. Since the AlGaN thickness is generally of the order with regard to jurisdictional claims in published maps and institutional affil- of a few tens of nanometers, the channel current strongly depends on the surface potential iations. change, thus resulting in sensitive responses from the sensor. Therefore, an AlGaN/GaN heterostructure would be a great candidate for the sensing platform. Various catalysts have been investigated for use in hydrogen sensors, including metals and metal oxides. Pt, Pd, and Ru are known to have high hydrogen solubility [17–26]. Metal oxides, such as ZnO, TiO2, SnO2, WO2, PdO, In2O3, and Fe2O3, have been studied Copyright: © 2021 by the authors. mostly as resistive sensors where adsorbed oxygen ions play an important role in the Licensee MDPI, Basel, Switzerland. reaction mechanism [27–40]. This article is an open access article distributed under the terms and Since the typical catalytic reaction with hydrogen occurs at elevated temperatures [41], conditions of the Creative Commons the sensor module must be heated using a separate or integrated heater, which incurs extra Attribution (CC BY) license (https:// power and time for stabilization. In addition, thermal heating of the catalyst and sensor creativecommons.org/licenses/by/ platform degrades long-term reliability [42]. Therefore, there is a strong demand for a hy- 4.0/). drogen sensor operating at room temperature without heating. A possible solution would Nanomaterials 2021, 11, 1422. https://doi.org/10.3390/nano11061422 https://www.mdpi.com/journal/nanomaterials Nanomaterials 2021, 11, x FOR PEER REVIEW 2 of 10 Nanomaterials 2021, 11, 1422 for a hydrogen sensor operating at room temperature without heating. A possible2 of 10 solution would be a photocatalytic reaction where the gas reaction with catalyst material is accel- erated by photoreaction. Indeed, it was reported that metal oxides reacted with hydrogen atbe room a photocatalytic temperature reaction with whereexposure the gas to reactionultraviole witht (UV) catalyst light material [43–47]. is acceleratedIn this study, by an Al- GaN/GaNphotoreaction. FET Indeed, sensor itwas was fabricated reported that using metal a dual oxides catalyst reacted layer with hydrogenwith ZnO-nanoparticles at room (NPs)temperature atop of with Pd exposure catalyst tofilm, ultraviolet which (UV) exhibited light [43 room–47]. Intemperature this study, an sensing AlGaN/GaN capability of FET sensor was fabricated using a dual catalyst layer with ZnO-nanoparticles (NPs) atop hydrogen with UV illumination. of Pd catalyst film, which exhibited room temperature sensing capability of hydrogen with UV illumination. 2. Experiment and Results 2. ExperimentFigure 1 illustrates and Results the synthesis process of ZnO-NPs. The precursor solution was the hydrolysisFigure 1of illustrates Zn(CH3COO) the synthesis2 2H2O (Sigma-Aldrich, process of ZnO-NPs. St. Louis, The precursor MO, USA) solution with wasKOH (Sam- chun,the hydrolysis Samchun, of Zn(CHSeoul,3 COO)South2 ·Korea,2H2O (Sigma-Aldrich, 95%) in methanol St. Louis, (Sigma-Aldrich, MO, USA) with St. KOHLouis, MO, (Samchun, Samchun, Seoul, South Korea, 95%) in methanol (Sigma-Aldrich, St. Louis, MO, USA, 99.9%). ZnO-NPs formed after 2 h reaction were separated by centrifugation. A de- USA, 99.9%). ZnO-NPs formed after 2 h reaction were separated by centrifugation. A taileddetailed synthesis synthesis process process and thethe characterization characterization for for the synthesizedthe synthesized ZnO-NPs ZnO-NPs can be can be foundfound in refref [[48].48]. FigureFigure 1. Synthesis process process for for ZnO-NPs. ZnO-NPs. The crystal structure of the ZnO-NPs was investigated using powder X-ray diffraction, whichThe is showncrystal in structure Figure2a. of The the crystal ZnO-NPs planes was of the investigated crystalline ZnO-NPs using powder corresponding X-ray diffrac- tion,to the which observed is shown diffraction in Figure peaks 2a. are The indicated crystal in planes the plot, of confirmingthe crystalline the successfulZnO-NPs corre- spondingsynthesis ofto ZnO-NPs.the observed The internaldiffraction and surfacepeaks ar chemicale indicated bonding in the state plot, of ZnO-NPs confirming was the suc- cessfulanalyzed synthesis through of X-ray ZnO-NPs. photoelectron The internal spectroscopy and surface (XPS). Figurechemical2b represents bonding thestate O of ZnO- NPs1 s spectrum was analyzed of ZnO-NPs through where X-ray three photoelectron distinct binding spectroscopy energy peaks (XPS). were Figure observed 2b represents at the529.6, O 1 531.0, s spectrum and 532.1 of eV,ZnO-NPs which corresponded where three to distinct the O atom binding in the energy Zn-O bonding peaks were (lattice observed − atoxygen), 529.6, oxygen531.0, and sublattice 532.1 imperfectioneV, which corresp (oxygenonded vacancy) to andthe surfaceO atom adsorbed in the Zn-O O2 of bonding (latticeZnO-NPs, oxygen), respectively oxygen [49 –sublattice51]. This XPS imperfecti result demonstrateson (oxygen thevacancy) presence and of thesurface ionized adsorbed oxygen molecules at the ZnO-NP surface, which plays an important role in the catalytic O2- of ZnO-NPs, respectively [49–51]. This XPS result demonstrates the presence of the reaction under UV illumination. The absorption spectrum of ZnO-NPs as a function of ionizedwavelength oxygen was alsomolecules measured at tothe estimate ZnO-NP the surface, optical bandgap which plays of ZnO-NPs. an important Figure3 a,brole in the catalyticshow the reaction absorption under spectrum UV illumination. and Tauc plot The of theabsorption ZnO-NPs spectrum thin film of from ZnO-NPs which the as a func- tionoptical of wavelength bandgap was was estimated also measured to be 3.24 eV. to Theesti widemate bandthe optical gap of ZnO-NPsbandgap can of ZnO-NPs. selectively Figure 3a,babsorb show UV lightthe absorption that can remove spectrum the oxygen and Tauc molecules plot adsorbedof the ZnO-NPs on the ZnO-NPs thin film surface. from which the optical bandgap was estimated to be 3.24 eV. The wide band gap of ZnO-NPs can selectively absorb UV light that can remove the oxygen molecules adsorbed on the ZnO- NPs surface. Nanomaterials 2021, 11, x FOR PEER REVIEW 3 of 10 NanomaterialsNanomaterials 20212021,,, 1111,,, 1422xx FORFOR PEERPEER REVIEWREVIEW 33 of of 1010 Figure 2. (a) X-ray diffraction pattern and (b) O 1s XPS spectra of as-synthesized ZnO-NPs. Figure 2. (a) X-ray diffraction patternpattern andand ((b)) OO 1s1s XPSXPS spectraspectra ofof as-synthesizedas-synthesized ZnO-NPs.ZnO-NPs. Figure 3. (a) Absorption spectrum and (b) Tauc plot of ZnO-NPs thin film. Figure 3. (a) Absorption spectrum andand ((b)) TaucTauc plotplot ofof ZnO-NPsZnO-NPs thinthin film.film. Figure 4a,b shows Transmission Electron Microscopy (TEM) and High-Resolution Figure4 4a,ba,b showsshows TransmissionTransmission Electron Electron Microscopy Microscopy (TEM) (TEM) and and High-Resolution High-Resolution TEM (HRTEM)Figure 4a,b images shows of TransmissionZnO-NPs, respective Electronly. Microscopy The size of ZnO-NPs(TEM) and was High-Resolution in the range TEM (HRTEM)(HRTEM) imagesimages of of ZnO-NPs, ZnO-NPs, respectively. respectively. The The size size of of ZnO-NPs ZnO-NPs was was in thein the range range of ofTEM 5–10 (HRTEM)nm. The lattice images fringe of ZnO-NPs, spacings ofrespective 0.28 andly. 0.25 The nm size observed of ZnO-NPs in HRTEM was inimage the range are 5–10of 5–10 nm.
Load more

Recommended publications
  • Gas Detection Products Ammonia & Other Gases
    Gas Detection Products Ammonia & Other Gases Product Catalog 2021 Table of Contents Price List .......................................................................................................................................................................................... 4-31 Controllers ....................................................................................................................................................................................... 32-39 GG-6 ....................................................................................................................................................................................... 32-33 GG-6 Remote Display ........................................................................................................................................................... 34-35 GG-2 ....................................................................................................................................................................................... 36-37 EM2 Entrance Monitor ......................................................................................................................................................... 38-39 Ammonia Sensors ............................................................................................................................................................................. 40-49 GG-NH3 .................................................................................................................................................................................
    [Show full text]
  • Testing the Performance of Hydrogen Sensors
    Testing the Performance of Hydrogen Sensors Nathan D. Marsh National Institute of Standards and Technology, Gaithersburg, MD USA Thomas G. Cleary National Institute of Standards and Technology, Gaithersburg, MD USA Abstract The acceptance of hydrogen as a widely-available energy source will depend to some extent on the perceived and actual safe dispensing and storage of hydrogen by the general public. Reliable detection of an accidental hydrogen gas release and mitigation of the hazard through designed safety systems is a key component of hydrogen powered systems in commercial, residential, and transportation uses. In anticipation of this emerging market, inexpensive hydrogen gas sensors based on a range of sensing technologies are becoming increasingly available. We have developed a new bench-scale test apparatus for hydrogen sensor performance, the Hydrogen Detector Environment Evaluator (HyDEE), based on our previous experience with hydrogen sensors in a small flow cell and in the Fire Emulator / Detector Evaluator. In particular, we have found that dynamic changes are relevant to hydrogen sensor performance, as they affect both response rate of the sensor and are also necessary to return the sensor environment to its baseline state. The ability to induce dynamic changes is most easily accomplished with a flow system similar to a small wind tunnel. In this system, we can expose sensors to hydrogen and other gases (particularly hydrocarbons, which many hydrogen sensors are also sensitive to) as well as humidity and changes in temperature. Improvements over the previous exploratory tests include substantially reduced volume allowing higher gas concentrations, and the ability to cool the system as well as heat it, in order to achieve a wider dynamic range in temperature and to more accurately simulate the environments to which sensors may be exposed in the real world.
    [Show full text]
  • 1 Nanocomposite Nio:Au Hydrogen Sensors with High Sensitivity And
    Nanocomposite NiO:Au hydrogen sensors with high sensitivity and low operating temperature M. Kandylaa*, C. Chatzimanolis-Moustakasa,b, E.P. Koumoulosb, C. Charitidisb, and M. Kompitsasa aNational Hellenic Research Foundation, Theoretical and Physical Chemistry Institute, 48 Vasileos Constantinou Avenue, 11635 Athens, Greece bNational Technical University of Athens, School of Chemical Engineering, 9 Heroon Polytechniou Street, 15780 Zografou, Greece Abstract We present results on the development of nanocomposite NiO:Au thin-film hydrogen sensors, which are able to detect hydrogen concentrations as low as 2 ppm in air, operating at low temperatures in the range 125 – 150oC. Thin NiO films were sputter- deposited on oxidized silicon substrates. The structural, morphological, and nanomechanical properties of the films were investigated with respect to post- deposition annealing. Au nanoparticles were added on the NiO surface via pulsed laser deposition and the films were tested as hydrogen sensors before and after Au deposition. The performance of the NiO films as hydrogen sensors improved significantly in the presence of Au nanoparticles on the surface. The detection limit (lowest detectable hydrogen concentration) decreased by two orders of magnitude, while the response time also decreased by a factor of three. KEYWORDS: A. composites, A. oxides, B. sputtering, B. laser deposition, D. electrochemical properties * Corresponding author: 1 M. Kandyla National Hellenic Research Foundation Theoretical and Physical Chemistry Institute 48 Vasileos Constantinou Avenue 11635 Athens, Greece Tel.: +30 210 7273826, Fax: +30 210 7273794 E-mail: [email protected] 2 1. Introduction Hydrogen is widely used in the chemical, petroleum, and metallurgical industries, as well as in power station cooling.
    [Show full text]
  • Hydrogen Sensor Specifications
    Control Instruments Corporation Product Specifications 25 Law Drive, Fairfield, NJ 07004-3295 USA Hydrogen Sensor for SmartMaxII Telephone 973-575-9114 Fax 973-575-0013 Email: [email protected] Internet: www.controlinstruments.com Sensor Design The Hydrogen Sensor employs electrochemical 9.375 inches technology. The sample diffuses into a micro fuel cell, where it chemically reacts to produce an electrical current. The micro fuel cell is designed so that the current produced is 3.625 inches proportional to the concentration of hydrogen present. The signal is then amplified into a mA output. The output signal is linear and readings are displayed in parts per million Cell Housing concentrations. Calibration Port Junction Box Construction Standard Specifications The sensor assembly consists of the micro fuel cell which Part Number SNR476 plugs into the electronics. The cell and electronics are Standard Range 0-1000 Parts Per Million (PPM) housed in an aluminum sensor body which connects to a Optional Range 0-2000 PPM junction box for field wiring. A collar protects the sensor Accuracy ± 5 PPM from environmental conditions and also provides a means of Response Time 40 seconds to 50% of scale introducing calibration test gas. Repeatability ± 1% full scale The micro fuel cell employs a capillary diffusion barrier Drift ± 2% full scale per month which eliminates the possibility of puncturing the membrane Assembly Rating Class 1, Division 1 and destroying the cell. The cell is a rugged and stable Assembly Material Aluminum design that is less sensitive to temperature and pressure Operating Life 2 years variations than other electrochemical cells. Storage life in container 6 months An on-board heater protects the cell and extends its Temperature Limits -20°C (-4°F) to 50°C (122°F) useful operating range in sub-freezing temperatures.
    [Show full text]
  • High-Sensitivity and Low-Power Flexible Schottky Hydrogen Sensor Based on Silicon Nanomembrane
    Poster Session II: IoT Including Nanosensors High-sensitivity and Low-power Flexible Schottky Hydrogen Sensor based on Silicon Nanomembrane Minkyu Cho Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST) . Hydrogen (H2) is useful as a future clean energy resource and an ideal replacement for fossil fuel . Various applications such as hydrogen vehicle, petroleum refining, glass purification, semiconductor manufacturing etc. H2 is flammable at concentrations over 4% by volume, therefore high sensitivity H2 sensor with fast response time is necessary . Silicon nanomembrane based diode type H2 sensor was demonstrated exhibiting high sensitivity and low power consumption Source:http://www.hydrogen.energy.gov/systems_integration.html US Department of energy High Mobility Advantages of Si • Well established processing technique Graphene -> more freedom in sensor design Carbon Nanotubes GaAs, GaN Low flexible rigidity of thin Si *Si Poly-Si a-Si Polymers Good material candidate for Low Mobility high performance flexible/wearable H2sensors . The operation principle of the sensor is based on Schottky barrier lowering effect upon exposure to H2 . H2 gas molecules are diffused into Pd layer forming Palladium Hydride (PdHx) at Pd/Si interfaces . Device simulations show that effective current quenching has been occurred in 50 nm thickness SiNM H2 lowering standby power consumption of the sensor Reduced Si thickness Low standby power consumption Excellent mechanical properties o Low thermal budget (< 110 C) Applicable to wafer-scale process . High Sensitivity ( > 700% @ 0.5% H2 concentration) and Fast Response Time (τ10−90= 22s) . Good Linearity (R2 > 0.98) and Low Limit of Detection (50 ppm, limited by MFC) . Minor Increased Sensitivity under Tensile Strain (Piezoresistive property of SiNM) .
    [Show full text]
  • Hydrogen Gas Sensors Based on Semiconductor Oxide Nanostructures
    Sensors 2012, 12, 5517-5550; doi:10.3390/s120505517 OPEN ACCESS sensors ISSN 1424-8220 www.mdpi.com/journal/sensors Review Hydrogen Gas Sensors Based on Semiconductor Oxide Nanostructures Haoshuang Gu *, Zhao Wang and Yongming Hu Faculty of Physics and Electronic Technology, Hubei University, Wuhan 430062, China; E-Mails: [email protected] (Z.W.); [email protected] (Y.H.) * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +86-027-8866-5568; Fax: +86-027-8866-3390. Received: 8 March 2012; in revised form: 1 April 2012 / Accepted: 25 April 2012 / Published: 30 April 2012 Abstract: Recently, the hydrogen gas sensing properties of semiconductor oxide (SMO) nanostructures have been widely investigated. In this article, we provide a comprehensive review of the research progress in the last five years concerning hydrogen gas sensors based on SMO thin film and one-dimensional (1D) nanostructures. The hydrogen sensing mechanism of SMO nanostructures and some critical issues are discussed. Doping, noble metal-decoration, heterojunctions and size reduction have been investigated and proved to be effective methods for improving the sensing performance of SMO thin films and 1D nanostructures. The effect on the hydrogen response of SMO thin films and 1D nanostructures of grain boundary and crystal orientation, as well as the sensor architecture, including electrode size and nanojunctions have also been studied. Finally, we also discuss some challenges for the future applications of SMO nanostructured hydrogen sensors. Keywords: hydrogen gas sensor; semiconductor oxides; nanostructure; thin films; one-dimensional nanostructures 1. Introduction Hydrogen is regarded as one of the best clean energy carriers, which is the ultimate fossil fuel candidate, with a high heat of combustion (142 kJ/g), low minimum ignition energy (0.017 mJ) and wide flammable range (4–75%), as well as high burning velocity.
    [Show full text]
  • Comparison of Available Portable Combustible Gas and Hydrogen Sensors
    Comparison of Available Portable Combustible Gas and Hydrogen Sensors June 2011 FOREWORD This report documents a comparison of currently commercially available portable equipment that can be used to sense/detect the presence of hydrogen and/or combustible gases in the air. Available devices, identified via a literature search, were compared and ranked based on a common set of ranking criteria and an objective rating system for each criterion. The devices were rated against each criterion based on data contained in manufacturer literature. This document is intended as a reference for the Federal Motor Carrier Safety Administration in evaluating available equipment that might be used by agency inspectors to search for fuel leaks from commercial vehicles powered by hydrogen. In the context of this report, the presence of hydrogen detected in a concentration greater than 25 percent of the lower flammable limit (LFL) of hydrogen in the air would be considered a leak. Such a search would most likely be done in the context of a roadside vehicle inspection conducted in accordance with the North American Standard Inspection Procedures. In accordance with current inspection procedures, a fuel leak would be grounds to declare a vehicle out of service for a safety violation. Given that hydrogen is a colorless, odorless gas, it is unlikely that any vehicle inspector could identify a small leak (as defined above) from a hydrogen fuel system without the aid of detection equipment. NOTICE This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The United States Government assumes no liability for its contents or the use thereof.
    [Show full text]
  • Trends in Gas Sensor Development for Hydrogen Safety
    TRENDS IN GAS SENSOR DEVELOPMENT FOR HYDROGEN SAFETY Hübert, T. 1, Boon-Brett, L. 2, Palmisano, V. 2, Frigo, G. 3, Hellstrand, Å. 3, Kiesewetter, O. and May, M. 4 1 BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, 12205 Berlin, Germany, [email protected] 2 European Commission – Joint Research Centre (JRC) Institute for Energy and Transport, Westerduinweg 3, (P.O.Box 2), 1755 ZG Petten, The Netherlands, [email protected] 3 Sensitron S.r.J., Viale della Republica 48, I-20010 Comaredo, Italy, [email protected] 4 UST Umweltsensortechnik GmbH, Dieselstraße 2, D-98716 Geschwenda, Germany, [email protected] Abstract Gas sensors are applied for facilitating the safe use of hydrogen in, for example, fuel cell and hydrogen fuelled vehicles. New sensor developments, aimed at meeting the increasingly stringent performance requirements in emerging applications are presented based on in-house technical developments and a literature study. The strategy of combining different detection principles, i.e. sensors based on electrochemical cells, semiconductors or field effects in combination with thermal conductivity sensor or catalytic combustion elements, in one new measuring system is reported. This extends the dynamic measuring range of the sensor while improving sensor reliability to achieve higher safety integrity through diverse redundancy. The application of new nanoscaled materials, nano wires, carbon tubes and graphene as well as the improvements in electronic components of field- effect, resistive-type and optical systems are evaluated in view of key operating parameters such as sensor response time, low energy consumption and low working temperature. 1.0 INTRODUCTION Fuel cell systems, usually consisting of gas preparation and supply modules, pipes, connections, valves as well as a fuel cell stack, are susceptible to hydrogen leakages.
    [Show full text]
  • Application of Nanotechnogy on Hydrogen Production and Storage
    The 21st Century Frontier 과학기술부 21세기 프론티어연구개발사업 21st Century Frontier R&D Program APPLICATIONAPPLICATION OFOF NANOTECHNOGYNANOTECHNOGY ONON HYDROGENHYDROGEN PRODUCTIONPRODUCTION ANDAND STORAGESTORAGE ININ KOREAKOREA April 26~27, 2007 Jong Won Kim Director Hydrogen Energy R&D Center http://www.h2.re.kr 4th US-Korea NanoForum, Honolulu, USA, April 26-27, 2007 1 th 4수소에너지사업단US-Korea NanoForum, 업무보고 Honolulu,, 2004.7.9 USA, April 26-27, 2007 Hydrogen Energy R&D Center 1 The 21st Century Frontier Outline I. Hydrogen Economy- Vision II. Technical barrier III. Current R&D activities related to nanotechnology IV. Conclusions 4th US-Korea NanoForum, Honolulu, USA, April 26-27, 2007 2 th 4수소에너지사업단US-Korea NanoForum, 업무보고 Honolulu,, 2004.7.9 USA, April 26-27, 2007 Hydrogen Energy R&D Center 2 The 21st Century Frontier 1. Hydrogen economy-vision Hydrogen Economy Nuclear Hydrogen storage/transportation/distribution Ship Water Electrolysis Wind Infrastructure Bus Solar Photochemical/ Vehicle Thermochemical/ Biological H2 Production Biomass Distributed Power Residential Mobile Submarine 3 th 4수소에너지사업단US-Korea NanoForum, 업무보고 Honolulu,, 2004.7.9 USA, April 26-27, 2007 Hydrogen Energy R&D Center 3 The 21st Century Frontier 2. Technical barriers Production/ Amounts Utilization Utilization *Oil refinery (desulfurising, reforming) ~ 1% TPES *Chem.Ind.: Ammonia, fertilizer, methanol (Total Primary *Metal Industry *Food( Fat, oil) *welding *Electronics Energy supply) *cryogenic *Electric generator-cooling Raw materials User ~95% fossil fuel (NG etc) About 50million tons ~ 45% petroleum ~40% Chem. Ind. ~ 5% electrolysis ~15% others <35% sales >65% self-consumption DomesticDomestic 0.970.97 millionmillion tonton TradeTrade 4848 thousandthousand ton*ton* * Source: Bongjin Kim et al: “The status of domestic hydrogen production, consumption and distribution”, Trans.
    [Show full text]
  • Electrodes for Semiconductor Gas Sensors
    sensors Review Electrodes for Semiconductor Gas Sensors Sung Pil Lee Department of Electronic Engineering, Kyungnam University, 7 Kyungnamdaehak-ro, Masanhappo-gu, Changwon 51767, Korea; [email protected] Academic Editor: Giovanni Neri Received: 7 February 2017; Accepted: 22 March 2017; Published: 25 March 2017 Abstract: The electrodes of semiconductor gas sensors are important in characterizing sensors based on their sensitivity, selectivity, reversibility, response time, and long-term stability. The types and materials of electrodes used for semiconductor gas sensors are analyzed. In addition, the effect of interfacial zones and surface states of electrode–semiconductor interfaces on their characteristics is studied. This study describes that the gas interaction mechanism of the electrode–semiconductor interfaces should take into account the interfacial zone, surface states, image force, and tunneling effect. Keywords: electrodes; semiconductor gas sensors; electrode materials; interfacial layer; transport mechanism 1. Introduction There is a growing demand for gas sensors for efficient use of energy and raw materials, as well as to reduce environmental pollution despite increasingly complex manufacturing processes. The Taguchi sensor that detects reducing gases is the most well-known gas sensor [1], whereas an oxygen sensor based on an ion-conducting sensor is the second most famous type [2–5]. Research and development for gas sensors is conducted in two stages. The first stage is to develop a new sensor whose application is empirically optimized. The characteristics of sensitivity, selectivity, long-term drift, and reliability are defined though its operation mechanism, which is often not fully understood at that stage [6–10]. The second stage is to modify, optimize, and standardize the developed sensor system [11–14].
    [Show full text]
  • Gas & Specialty Sensors
    GAS & SPECIALTY SENSORS TOXIC AND COMBUSTIBLE GAS DETECTOR GDS SERIES DESCRIPTION The Kele GDS Series Gas Detector is a standalone micro-processor-based system for continuous, effective monitoring of toxic and combustible gases. The GDS Series provides a 4-20 mA output in proportion to the level of gas present and two relay outputs to activate additional horns, strobes, or ventilation systems. The modular design adds functionality and flexibility with pre-calibrated plug-in sensors. The unit features a two-line LCD for local indication, self test diagnostics, and a built-in 85 dBA buzzer. The rugged polycarbonate housing is resistant to rust, corrosion, and dents. The GDS Series Gas Detector is designed to be used as part of a control system that helps to prevent the formation of a hazardous environment when properly installed and maintained. 7 GDS FEaturES GAS & SPECIALTY SENSORS • Pre-calibrated plug-in sensors • Wall or duct mount • Built-in 85 dBA buzzer • Easy installation, commissioning, and operation • 4-20 mA and two relay outputs • LED status indication • Wide variety of gases detected • Password protection • Two-line LCD display • Programmable relay differential SPEcificatioNS Supply Voltage 17-27 VAC @ 8.4 VA, 50/60 Hz or Display 8 character, two-line LCD 24-38 VDC @ 350 mA Display Resolution (E3SAH base unit is 120 VAC only) CO 1 ppm Accuracy ±3% O2 0.2% Signal Output 4-20 mA @ 500Ω H2S, NO2 0.2 ppm CH4, C3H8, H2 0.5% Measurement Range Relay Output (2) DPDT pilot duty, 150 VA max CO 0-250 ppm inductive, 5A @ 30 VDC, 250 VAC
    [Show full text]
  • Paper Is a Good Sensor Platform with Significant Positive Performance Metrics
    AN OVERVIEW OF HYDROGEN SAFETY SENSORS AND REQUIREMENTS Buttner, W.J.1 Post, M.B.2, Burgess, R.3, and Rivkin, C.4 1 Hydrogen Technologies & Systems Center, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO 80401, USA, [email protected] 2 Hydrogen Technologies & Systems Center, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO 80401, USA, [email protected] 3 Hydrogen Technologies & Systems Center, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO 80401, USA, [email protected] 4 Hydrogen Technologies & Systems Center, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO 80401, USA, [email protected] ABSTRACT There exists an international commitment to increase the utilization of hydrogen as a clean and renewable alternative to carbon-based fuels. The availability of hydrogen safety sensors is critical to assure the safe deployment of hydrogen systems. Already, the use of hydrogen safety sensors is required for the indoor fueling of fuel cell powered forklifts (e.g., NFPA 52, Vehicular Fuel Systems Code [1]). Additional Codes and Standards specific to hydrogen detectors are being developed [2, 3], which when adopted will impose mandatory analytical performance metrics. There are a large number of commercially available hydrogen safety sensors. Because end-users have a broad range of sensor options for their specific applications, the final selection of an appropriate sensor technology can be complicated. Facility engineers and other end-users are expected to select the optimal sensor technology choice. However, some sensor technologies may not be a good fit for a given application. Informed decisions require an understanding of the general analytical performance specifications that can be expected by a given sensor technology.
    [Show full text]