Review
Hydrogen sensors – A review

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Abstract

Hydrogen sensors are of increasing importance in connection with the development and expanded use of hydrogen gas as an energy carrier and as a chemical reactant. There are an immense number of sensors reported in the literature for hydrogen detection and in this work these sensors are classified into eight different operating principles. Characteristic performance parameters of these sensor types, such as measuring range, sensitivity, selectivity and response time are reviewed and the latest technology developments are reported. Testing and validation of sensor performance are described in relation to standardisation and use in potentially explosive atmospheres so as to identify the requirements on hydrogen sensors for practical applications.

Introduction

Hydrogen has a number of unusual properties in comparison to other combustible gases and vapours, such as methane, propane or gasoline vapour. These include a very low density (0.0899 kg/m3) and boiling point (20.39 K) combined with a high diffusion coefficient (0.61 cm2/s in air) and buoyancy. In terms of its combustion characteristics, it has a low minimum ignition energy (0.017 mJ), high heat of combustion (142 kJ/g H2) and wide flammable range (4–75%1), as well as a high burning velocity, detonation sensitivity and an ignition temperature of 560 °C. Hydrogen also acts as a strong reducing agent for many elements and has a high permeability through many materials, which demands special precautions in certain applications.

As a colourless, odourless and tasteless flammable gas hydrogen cannot be detected by human senses, and other means are therefore required to detect its presence and quantify the concentration. Rapid and accurate hydrogen gas concentration measurement is essential to alert to the formation of potentially explosive mixtures with air and to help prevent the risk of an explosion.

The detection and concentration measurement of hydrogen has a history of over 100 years beginning with hydrogen measurements at filling stations for airships [1]. However, there is a continued need for faster, more accurate and more selective detection of hydrogen gas in various areas of industry for monitoring and controlling hydrogen concentration. For example hydrogen gas concentration monitoring is important in the synthesis of ammonia and methanol, the hydration of hydrocarbons, the desulphurization of petroleum products and the production of rocket fuels. In metallurgical processes, the measurement of hydrogen concentration is also required. During the melting of aluminium [2] for example, the metal can react with water to form alumina and hydrogen, which remains dissolved in the melt. Hydrogen concentration must be monitored during welding and galvanic plating in order to avoid hydrogen embrittlement and is also a relevant parameter in the characterisation of batteries.

Monitoring of hydrogen concentration is essential to nuclear reactor safety. In nuclear power stations, hydrogen can be formed in radioactive waste tanks, during plutonium reprocessing, through the radiolysis of water or via the unwanted reaction of water with high temperature reactor core and cladding materials (uranium oxide, zirconium). A hydrogen explosion contributed to the nuclear accident at Three Mile Island in 1979 and to the Fukushima accident in 2011.

In coal mines hydrogen can be produced in the ppm2 range by methane or coal-dust explosions or by the spontaneous heating and low-temperature oxidation of coal [3]. The presence of hydrogen can be used to indicate a fire in its early state or to detect impending transformer failure in electric power plants. Hydrogen gas concentration is of relevance in semiconductor manufacturing, for which gases such as silanes and nitrogen must be produced with very high purity. In the lighting industry also, hydrogen is a contaminant that must be quantified during the production of krypton, xenon and neon. Hydrogen leak detection is performed at gas supply tubes and in process plants, where its presence can indicate corrosion or where hydrogen is used as a coolant for turbine generators. Liquid hydrogen is used as a fuel in space applications and hydrogen sensors are therefore used for leak detection during shuttle launches and other aerospace operations. Hydrogen sensing can also play a role in biomedical applications as an indicator for certain diseases and for the detection of environmental pollution [4].

Hydrogen is an energy carrier and can contribute to overcoming the problems of dwindling fossil fuel reserves, energy supply security and global warming. Ongoing research, development and as yet small-scale deployment of hydrogen technologies seek to realize this potential. In this emerging hydrogen economy, the detection of hydrogen leaks and the measurement of hydrogen concentration are necessary during production, storage, transportation and use in both stationary and mobile applications. Sensors will therefore be used for safety monitoring of hydrogen production plants, pipelines, storage tanks, refuelling stations and automotive vehicles.

Alternative hydrogen detection methods employ instruments such as gas chromatographs, mass spectrometers or specific ionisation gas pressure sensors. Gas chromatographs use columns to separate the individual gas components in a mixture and different types of detector to identify each component. Mass spectrometers identify gas molecules based on their characteristic deflections from a magnetic field. Traditionally, these instruments are relatively large, expensive, high maintenance and slow in terms of their sampling and reaction times. However, there has been significant progress in miniaturisation over the last decade and micro-electro-mechanical systems (MEMS) have been reported [5], [6]. These instruments are not considered further in this review.

Hydrogen sensors are transducer devices that detect hydrogen gas molecules and produce an electrical signal with a magnitude proportional to the hydrogen gas concentration [7]. Hydrogen sensors have several advantages over the conventional hydrogen detection methods mentioned above, including their lower cost, smaller size and faster response. These advantages make them more suitable for portable and in situ hydrogen detection in a range of applications. Such sensors are well-established for use in industry where they can be calibrated regularly and operated by trained personnel. However, the emergence of a hydrogen economy provides the impetus to produce low cost, low maintenance, easy to install, easy to use, accurate hydrogen sensors appropriate for use by untrained individuals in a variety of applications.

There are many different types of hydrogen sensor commercially available or in development. Most hydrogen sensing principles have been known for decades [8], [9] and hydrogen sensors have been commercially available for many years. In order to meet the demands of a future hydrogen economy however, a lot of research is ongoing to continuously improve sensitivity, selectivity, response time and reliability in addition to reducing sensor size, cost and power consumption. These demands on hydrogen sensors can be summarised as follows [10], [11], [12]:

  • indication of hydrogen in concentration range 0.01–10% (safety) or 1–100% (fuel cells)

  • safe performance i.e. explosion proof sensor design and protective housing

  • reliable results of sufficient accuracy and sensitivity (uncertainty <5–10% of signal)

  • stable signal with low noise

  • robustness including low sensitivity to environmental parameters such as:

    • temperature (−30–80 °C (safety), 70–150 °C (fuel cells))

    • pressure (80–110 kPa)

    • relative humidity (10–98%)

    • gas flow rate

  • fast response and recovery time (<1 s)3

  • low cross sensitivity (e.g. hydrocarbons, CO, H2S)

  • long life time (>5 years)

  • low power consumption (<100 mW)

  • low cost (<100 € per system)

  • small size

  • simple operation and maintenance with long service interval

  • simple system integration and interface

The increase in commercial interest and R&D due to the emergence of new and widespread applications for these devices is reflected in the growing number of relevant publications since the year 2000 in particular, Fig. 1.

The aim of this paper is to describe and review the operating principles of the main existing and emerging hydrogen sensing technologies. For each type the mechanism of operation is described and the characteristic properties are summarised. The advantages and shortcomings are then highlighted and recent technological developments and performance improvements are reviewed. Requirements on hydrogen sensors for technical applications are also briefly described to anticipate the sometimes exhausting path from laboratory invention to practical use. Information and data presented herein are collected from published literature and from the authors’ experience in hydrogen sensor testing.

Section snippets

Hydrogen detection technologies

Sensors can be used simply to identify the presence of hydrogen or to measure its concentration. Quantification of hydrogen concentration is important at the ppm level for the analysis of impurities, at the Lower Flammable Limit (LFL) level of 4% hydrogen in air for safety applications or at higher concentrations for monitoring and controlling processes. Interaction of hydrogen with the sensing element of a hydrogen detection device can cause changes in temperature, refractive index, electrical

Comparison of sensor technologies

Typical characteristics of the sensor types described in the previous section are summarised in Table 1. In a previous publication [12], we presented the results of a survey of the hydrogen sensor market and compared the performance specifications of commercially available sensors belonging to the different classes of technology. These specifications are summarised briefly in Table 2 to complement the information given in Table 1 which is derived from the sensor literature. However, there may

Technology developments

The increasing efforts in hydrogen sensor research and development are clearly visible by the increasing number of scientific publications in this field (Fig. 1). Most of the publications of the last 2 years originate from the USA (25%) and Japan (12%) followed by China, Taiwan, South Korea and India. In about 40% of papers the change of electrical characteristics in resistors, diodes and transistors has been studied. The second most researched group are optical sensors (15%) followed by

Sensor testing

Although the relationship between the basic sensor signal and the ambient hydrogen gas concentration may be known from physical laws or empirical functions, for practical applications a calibration is indispensable. This is usually performed first by the sensor manufacturer. After a certain time of operation however, a periodic recalibration will be required due to aging and poisoning effects. In addition, because sensors will be used under specific environmental conditions of gas composition,

Conclusions

There are a number of technologies that have been developed and demonstrated for the detection of hydrogen gas. Some of these are well-established commercially and devices based on these principles have been available for years, produced by various manufacturers and with a range of performance capabilities and costs. Other technologies are less well-developed, but ongoing research indicates that they show promise for emerging hydrogen detection applications that impose new performance

T. Hübert studied Chemistry at the Technical University of Freiberg and gained his Diploma in 1975. He has got his PhD (1982) and DSc (1991) in Solid State Chemistry and Materials Sciences. Dr. Hübert is currently working as head of laboratory and working group on chemical sensor technology and sol–gel chemistry at the BAM Federal Institute for Materials Research and Testing in Berlin, Germany. His topics are gas and humidity sensors. The activities comprise the development, testing,

References (274)

  • K. Tajima et al.

    Micromechanical fabrication of low-power thermoelectric hydrogen sensor

    Sens. Actuators B: Chem.

    (2005)
  • W. Shin et al.

    Planar catalytic combustor film for thermoelectric hydrogen sensor

    Sens. Actuators B: Chem.

    (2005)
  • H. Huang

    Thermoelectric hydrogen sensor working at room temperature prepared by bismuth-telluride P-N couples and Pt/gamma-Al2O3

    Sens. Actuators B: Chem.

    (2008)
  • M. Nishibori

    Robust hydrogen detection system with a thermoelectric hydrogen sensor for hydrogen station application

    Int. J. Hydrogen Energy

    (2009)
  • G. Pollak-Diener et al.

    Heat-conduction microsensor based on silicon technology for the analysis of two- and three-component gas mixtures

    Sens. Actuators B: Chem.

    (1993)
  • I. Simon et al.

    Thermal and gas-sensing properties of a micromachined thermal conductivity sensor for the detection of hydrogen in automotive applications

    Sens. Actuators B: Chem.

    (2002)
  • Y.C. Weng

    Amperometric hydrogen sensor based on PtxPdy/Nafion electrode prepared by Takenata-Torikai method

    Sens. Actuator B: Chem.

    (2009)
  • Y. Chao et al.

    Amperometric sensor for selective and stable hydrogen measurement

    Sens. Actuators B: Chem.

    (2005)
  • X. Lu

    Solid-state amperometric hydrogen sensor based on polymer electrolyte membrane fuel cell

    Sens. Actuator B

    (2005)
  • S. Zhuiykov

    Hydrogen sensor based on a new type of proton conductive ceramic

    Int. J. Hydrogen Energy

    (1996)
  • N. Taniguchi et al.

    Characteristics of novel BaZr0.4Ce0.4In0.2O3 proton conducting ceramics and their application to hydrogen sensors

    Solid State Ionics

    (2005)
  • M. Sakthivel et al.

    A portable limiting current solid-state electrochemical diffusion hole type hydrogen sensor device for biomass fuel reactors: engineering aspect

    Int. J. Hydrogen Energy

    (2008)
  • H. Böhm

    Anodische Oxydation von Wasserstoff an Wolframcarbid

    Electrochim. Acta

    (1970)
  • L.P. Martin et al.

    Electrochemical hydrogen sensor for safety monitoring

    Solid State Ionics

    (2004)
  • Y. Okuyama

    A new type of hydrogen sensor for molten metals usable up to 1600 K

    Electrochim. Acta

    (2009)
  • M. Nogami et al.

    Hydrogen sensor prepared using fast proton-conducting glass films

    Sens. Actuators B

    (2006)
  • N. Maffei et al.

    A solid-state potentiometric sensor for hydrogen detection in air

    Sens. Actuators B: Chem.

    (2004)
  • H. Iwahara et al.

    Studies on solid electrolyte gas cells with high-temperature-type proton conductor and oxide ion conductor

    Solid States Ionics

    (1983)
  • R. Bouchet et al.

    Solid-state hydrogen sensor based on acid-doped polybenzimidazole

    Sens. Actuators B

    (2001)
  • P.K. Sekhar

    Development and testing of a miniaturized hydrogen safety sensor prototype

    Sens. Actuators B

    (2010)
  • T. Schober

    Applications of oxidic high-temperature proton conductors

    Solid State Ionics

    (2003)
  • I. Kosacki et al.

    Nanostructured oxide thin films for gas sensors

    Sens. Actuators B: Chem.

    (1998)
  • V. Aroutiounian

    Metal oxide hydrogen, oxygen, and carbon monoxide sensors for hydrogen setups and cells

    Int. J. Hydrogen Energy

    (2007)
  • T. Hyodo

    Hydrogen sensing properties of SnO2 varistors loaded with SiO2 by surface chemical modification with diethoxydimethylsilane

    Sens. Actuators B: Chem.

    (2000)
  • S.J. Ippolito

    Hydrogen sensing characteristics of WO3 thin film conductometric sensors activated by Pt and Au catalysts

    Sens. Actuators B: Chem.

    (2005)
  • V.V. Malyshev et al.

    Investigation of gas-sensitivity of sensor structures to hydrogen in a wide range of temperature, concentration and humidity of gas medium

    Sens. Actuators B: Chem.

    (2008)
  • G. Tournier et al.

    Selective filter for SnO2-based gas sensors: application to hydrogen trace detection

    Sens. Actuators B: Chem.

    (2005)
  • A. Lee et al.

    Temperature modulation in semiconductor gas sensing

    Sens. Actuators B: Chem.

    (1999)
  • Z. Ankara et al.

    Low power virtual sensor array based on a micromachined gas sensor for fast discrimination between H2, CO and relative humidity

    Sens. Actuators B: Chem.

    (2004)
  • C.-H. Han et al.

    Micro-bead of nano-crystalline F-doped SnO2 as a sensitive hydrogen gas sensor

    Sens. Actuators B: Chem.

    (2005)
  • S. Shukla

    Room temperature hydrogen response kinectics of nano-micro-integrated doped tin oxide sensor

    Sens. Actuators B: Chem.

    (2007)
  • L. Boon-Brett et al.

    Reliability of commercial available hydrogen sensors for detection of hydrogen at critical concentrations: part I – testing facility and methodologies

    Int. J. Hydrogen Energy

    (2008)
  • L. Boon-Brett et al.

    Reliability of commercial available hydrogen sensors for detection of hydrogen at critical concentrations: part II – selected sensor test results

    Int. J. Hydrogen Energy

    (2009)
  • J. Ravi Prakash et al.

    Hydrogen sensors: role of palladium thin film morphology

    Sens. Actuators B: Chem.

    (2007)
  • P. Kumar et al.

    Palladium capped samarium thin films as potential hydrogen sensors

    Mater. Chem. Phys.

    (2004)
  • F. DiMeo

    MEMS-based hydrogen gas sensors

    Sens. Actuators B: Chem.

    (2006)
  • A. Trinchi et al.

    High temperature field effect hydrogen and hydrocarbon gas sensors based on SiC MOS devices

    Sens. Actuators B: Chem.

    (2008)
  • MAN Company, Vorrichtung zur fortlaufenden Bestimmung des Wasserstoffgehaltes in Gasgemischen, Patent DRP 165 349...
  • C. Schwandt et al.

    Hydrogen sensing in molten aluminum using a commercial electrochemical sensor

    Ionics

    (2000)
  • M.P. Brungs

    The evaluation of hydrogen detectors for use in coal mines

    J. Inst. Energy

    (1992)
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    T. Hübert studied Chemistry at the Technical University of Freiberg and gained his Diploma in 1975. He has got his PhD (1982) and DSc (1991) in Solid State Chemistry and Materials Sciences. Dr. Hübert is currently working as head of laboratory and working group on chemical sensor technology and sol–gel chemistry at the BAM Federal Institute for Materials Research and Testing in Berlin, Germany. His topics are gas and humidity sensors. The activities comprise the development, testing, calibration and certification of sensors in an accredited laboratory. Different types of hydrogen sensors are under investigation especially for automotive application. Dr Hübert takes part in national and international standardisation activities including ISO working group for hydrogen detection apparatus.

    L. Boon-Brett received her PhD in Combustion Chemistry from the National University of Ireland, Galway in 1999. In 2002 she joined the JRC Institute for Energy as a postdoctoral fellow testing high pressure hydrogen storage tanks and subsequently designing a hydrogen safety sensor testing facility. Following this she worked at the Rocket Technology Group of TNO in The Netherlands investigating the application of solid gas generator technology for hydrogen storage. She rejoined the JRC in April 2007 as task leader for hydrogen safety sensor performance testing, evaluation and application.

    G. Black completed a BSc in Chemistry at University College Dublin, Ireland, followed by an MSc in Science Communication at Dublin City University. She completed her PhD in 2009 at the National University of Ireland, Galway, entitled “The Combustion Chemistry of Oxygenates: A Computational, Modelling and Experimental Study”. Part of this work was carried out at the CNRS laboratory in Orléans, France. Since the start of 2009 she has been employed at the Institute for Energy of the Joint Research Centre of the European Commission, where she works on test method development and performance testing of hydrogen safety sensors.

    Ulrich Banach received his PhD in Inorganic Chemistry from Martin-Luther-University in Halle, Germany, in 1979. He works as a scientist at the BAM Federal Institute for Materials Research and Testing in Berlin, Germany. His research interests are focused on dielectric properties of glassy and ceramic materials and thin films. He has been involved for many years in the testing and validation of gas and humidity sensors including hydrogen detectors.

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