Amperometric Hydrogen Sensor Research Articles

Hydrogen Sensor to Monitor the Conditions in the Primary Circuit of a Nuclear Reactor

AbstractA hydrogen concentration measurement device is developed for nuclear reactor primary circuits water. Despite the necessity to monitor hydrogen, only one producer offers a really selective hydrogen sensor on the world market because of the complexity of the device preparation when long‐term signal stability is required. Therefore, the Mass Transfer Laboratory at UCT Prague shares the experience gained during the sensor development. The results of the amperometric hydrogen sensor laboratory tests are presented, which demonstrate how to improve the sensor durability. An operational test in Dukovany nuclear power plant confirmed a significant improvement of the latest sensor version and showed that a simple principle could be realized in the form of a reliable device for industrial measurements.

Hydrogen Sensor with 3D Printed BaCe0.6Zr0.3Y0.1O3-α electrolyte for High-Temperature Applications

Fusion energy is considered a promising source of energy for the near future. The most efficient reaction for that purpose is the fusion of deuterium and tritium, two hydrogen isotopes, to release helium, neutrons and energy. To assure the correct operation of this technology, new online devices able to monitor hydrogen isotopes will be required.Electrochemical sensors based on solid-state proton conductor ceramics can be used for that purpose. These materials have attracted significant interest because of their chemical and physical durability, especially at elevated temperatures. These electrolytes are perovskite-type materials with electrical carriers, positive holes, excess electrons and oxide ion vacancies. In previous work [1], amperometric hydrogen sensors based on BaCe0.6Zr0.3Y0.1O3-α (BCZY) electrolyte have been developed and tested in hydrogen atmospheres obtaining good results. These prototypes were constructed using 13 mm BCZY disks obtained by uniaxial pressure.In the present work, hydrogen sensors based on BCZY were constructed and evaluated in amperometric mode. The BCZY powder was disk-shaped using uniaxial pressure and 3D printing. Sensors were constructed as follows: first, sintered disks were platinized using platinum ink. Then, disks were sealed with a glass binder to alumina tubes. This way, the external face of the disk acted as a working electrode (WE) and the inner part of the sensor as a counter electrode (CE). 3D printed disks were fabricated using a Delta WASP 2040 ceramic 3D printer. For that, the ceramic powder was mixed with PEG400 and water until a viscous paste was obtained. Once green bodies were dried, they were heated for debinding and sintering using an optimized thermal program to reduce porosity. XRD (for crystallographic phases) and SEM (for microstructural defects and sintering) were used for the 3D printed and uniaxial pressed sintered disks characterization. The amperometric response of sensors constructed with both electrolytes (the uniaxially pressed and the 3D printed disks) was compared.[1] A. Hinojo, I. Soriano, J. Abellà, S. Colominas, Evaluation of High-Temperature Hydrogen Sensors Based on BaCe0.6Zr0.3Y0.1O3-α and Sr(Ce0.9Zr0.1)0.95Yb0.05O3-α Perovskites for Industrial Applications, Sensors. 20 (2020) 7258. https://doi.org/10.3390/s20247258.

Amperometric hydrogen sensor based on pyrrolidinium hydrogen sulfate under anaerobic conditions

• An amperometric hydrogen sensor that based on [Py] [HSO 4 ]/PVDF composite membranes • The hydrogen sensor could operate under anaerobic conditions. • The sensing mechanism of hydrogen sensors with proton ionic liquid electrolytes was investigated. Hydrogen as a sustainable energy source can contribute to overcoming the shortage of fossil fuel. The storage and transport of hydrogen will further increase the demand for sensors that detect trace amounts of hydrogen in anaerobic conditions. So, we have designed an innovative amperometric hydrogen sensor that based on protic ionic liquid (PIL) electrolyte. The sensor based on [Py][HSO 4 ] was found to be highly sensitive and selective to hydrogen with a good linearity and long-term stability. The sensor also demonstrates its potential in the field of hydrogen fuel storage by providing excellent performance at low temperatures.

Amperometric Hydrogen Sensor Based on Solid Polymer Electrolyte and Titanium Foam Electrode.

Trace hydrogen detection plays an important role in the safety detection of lithium-ion batteries (LIBs) due to the generation and leakage of trace hydrogen in the early stage of LIBs damage. In this work, an amperometric hydrogen sensor based on solid polymer electrolyte was reported. The sandwich device structure was realized, which could directly diffuse the gas from both sides to the three-phase interface (gas/electrode/electrolyte) to participate in the reaction through the optimal design of the gas diffusion path. Then, platinum nanoparticles (Pt-NPs) were loaded on the metal foam by electroplating, and the porous electrode was filled with solid polymer electrolyte. A sensor with high specific surface area, high catalytic activity, and high sensitivity was obtained. Finally, the hydrogen oxidation reaction (HOR) mechanism of the platinum-loaded (Pt-loaded) titanium foam (Ti foam) electrode under both anaerobic and aerobic conditions was verified, and the properties of the sensor was evaluated. The hydrogen sensor with a “sandwich” structure has the advantages of high sensitivity, good stability, low detection limit and low cost, which provides a technical solution for the safety and real-time monitoring of LIBs.

Evaluation of High-Temperature Hydrogen Sensors Based on BaCe0.6Zr0.3Y0.1O3-α and Sr(Ce0.9Zr0.1)0.95Yb0.05O3-α Perovskites for Industrial Applications

In many industrial fields, there is a need to design and characterize on-line and on-board hydrogen monitoring tools able to operate under extreme conditions. One of these applications is in future nuclear fusion reactors, which will use hydrogen isotopes as a plasma fuel. In this context, the measurement of the concentration of these hydrogen isotopes will be of interest to ensure the correct operating conditions for such reactors. Hydrogen sensors based on solid-state electrolytes will be the first step in the development of new analytical tools able to quantify deuterium and tritium in aggressive environments. In the present work, amperometric hydrogen sensors were constructed and evaluated using two solid-state electrolytes, BaCe0.6Zr0.3Y0.1O3-α and Sr(Ce0.9Zr0.1)0.95Yb0.05O3-α. Prototype sensors were built in order to study their sensitivity in on-line measurements. The experiments were performed in a reactor with a hydrogen-controlled environment. The sensors were evaluated at 500 and 600 °C in amperometric mode by applying 2 and 4 V voltages between electrodes. Both sensors showed increases in sensitivity when the temperature or voltage were increased.

Potentiometric Vs. Amperometric Modes for High Temperature Hydrogen BaCe0.6Zr0.3Y0.1O3-Α Sensor

Fusion energy is considered a source of energy for the near future, due to its no contribution to the greenhouse effect. In a fusion reactor, deuterium and tritium collide and fuse, releasing helium, neutrons and energy. Deuterium can be obtained from water, however tritium must be in situ generated [1]. ITER (International Thermonuclear Experimental Reactor) is being constructed for testing the technology, materials and R&D concepts in order to evaluate its energy gain. One of its goals is to verify the tritium self-sufficiency by breeding systems [2], including the molten Pb-15.7Li eutectic alloy.In this frame, the chemically aggressive and reducing environment creates the necessity to design new devices for tritium concentration monitoring in the lithium-lead eutectic [3]. For this purpose, electrochemical sensors based on proton-conducting solid-state electrolytes have been proved to be able to operate at high temperatures, with high physical and chemical stabilities. These electrolytes are perovskite phase materials, in which the electrical carriers are positive holes, excess electrons, oxide ion vacancies and interstitial protons, which interact with oxide ions.Different proton-conducting solid-state electrolytes have been studied previously in the Electrochemical Methods Laboratory at Institut Quimic de Sarria (IQS). These solid electrolytes have been employed in the construction of electrochemical probes that can work on potentiometric and amperometric modes [4]. In the present work, the response of potentiometric and amperometric hydrogen sensors, constructed with BaCe0.6Zr0.3Y0.1O3-α ceramic electrolyte, was compared. The sensors consisted on an open alumina tube with a sealed proton conducting ceramic pellet in one side. Both sides of the pellet were platinized and connected to platinum wires. The wires ends were the positive and the negative poles of the sensor.Both operating modes were tested at different hydrogen and argon mixtures at the working compartment. In the potentiometric mode, the potential difference between both electrodes was measured and it was compared with the theoretical value calculated from the Nernst equation. In the reference electrode, the hydrogen partial pressure was kept constant during all the experiments. Moreover, the amperometric sensor measured the current through both electrodes when a voltage was applied, obtaining a calibration curve.

High temperature hydrogen selective solid-state electrolyte sensor fabricated by slip casting

Tritium management is one of the main challenges that future nuclear fusion energy has to achieve. Accurate tritium monitoring is a basic task in order to have relying fusion reactors. High temperature sensors have to be developed to make this monitoring a reality. Hydrogen sensors based on solid-state electrolytes can be a reliable option to perform this monitoring. These types of sensors offer resistance to harsh chemical environments, temperature depending conductivity and quick and easy to measure signals.Potentiometric and amperometric hydrogen sensors based on solid-state electrolytes were previously studied in our research group. These previous sensors contained a pellet-shaped solid-state electrolyte. Using a one-end closed tube geometry the active area of the sensor increases. This new shape was obtained by a slip casting process. The satisfactory results obtained with both amperometric and potentiometric sensors present a promising path to the development of high temperature tritium sensors that could be used in the breeding blankets of the future nuclear fusion reactors.In the present work, amperometric sensors performance has been improved by increasing the electrolyte’s active area. Enlarging the electrolyte’s area gives the sensor more sensitivity and reduces its limit of detection and quantification. Analytical parameters of the sensor were compared to other electrochemical hydrogen sensors.

An amperometric hydrogen sensor based on Pt nanoparticles supported multi-wall carbon nanotubes

An amperometric H2 gas sensor was fabricated on microporous PTFE sheet using Pt NP-decorated on multiwalled carbon nanotubes (MWNTs) via wet chemical synthesis and vacuum filtration processes. The various material analysis methods such as SEM coupled with EDS, TEM, and XRD were employed in order to characterize microstructures, morphologies and elemental composition of the prepared Pt-MWNTs material. The electrode showed the nanoporous structures with intricate surface morphology as a consequence of Pt agglomerates bonded to MWNTs. The TEM and XRD results confirmed the small Pt nanoparticles (Pt NPs) sizes of 0.5–4.7nm and the polycrystalline face-centered cubic (fcc) structures. The measured electrochemical surface area (ESA) of the Pt-MWNTs-modified glassy carbon electrode was 235.2cm2/mg by using cyclic voltammetry (CV) which was 1.2 times higher than that of commercial 20wt% Pt-C (E-Tek). Furthermore, amperometric gas sensing measurements were performed to evaluate the gas sensing properties of sensor. The Pt-MWNTs electrode shows high sensitivity of 0.269μA/ppm in H2 detection, an excellent linear response, reproducibility and long term stability. Moreover, this electrode was also evaluated in terms of response and recovery times, high detective limit of cross-selectivity to interfering species such as CO, NH3. Therefore, the obtained results show good sensing performance of Pt-MWNTs electrode of H2 detection.

Comparative study of sensing behavior of brush coated, electrodeposited and pulsed electrodeposited Pt/GDE based amperometric hydrogen sensors

Method of deposition of Electro-catalyst plays a significant role in the sensing behavior of electrochemical sensors for hydrogen. Amperometric hydrogen sensor operating in fuel cell mode with Nafion as proton conducting electrolyte, platinum as sensing and counter electrodes has been developed. A comparative study of response behavior of hydrogen sensors with brush coated, electrodeposited and pulsed electrodeposited Pt on gas diffusion electrode (GDE) was undertaken in the concentration range of 0–4 % H2/Ar. The crystal structure and microstructure of Pt/GDE were characterized by gracing incidence X-ray diffraction and field emission scanning electron microscopy. In-situ electrochemical impedance spectroscopy was carried out for the sensors with H2/Ar at sensing electrode side. The investigations revealed that Pt/GDE fabricated by pulsed electro-deposition has better sensitivity, response time and stability compared to the brush-coated and electrodeposited Pt/GDE sensors. Improved response of sensor with Pt/GDE fabricated by pulsed electro-deposition is explained based on microstructure of Pt electro-catalyst and interfacial characteristics of electrodes with Nafion.

Amperometric hydrogen sensors for application in fusion reactors

Accurate and reliable tritium management is of basic importance for the correct operation conditions of the blanket tritium cycle. The determination of the hydrogen isotopes concentration in liquid metal is of high interest for the liquid breeder blankets (like Helium-Cooled Lithium–Lead or Dual Coolant ‘He/Pb17Li’ blankets) correct design and operation. Sensors based on solid state electrolytes can be used to that purpose. These types of sensors offer quick and easy to measure signals, high chemical stability and temperate depending ionic conductivity.Potentiometric hydrogen sensors based on solid state electrolytes were previously studied at the Electrochemical Methods Laboratory at Institut Químic de Sarrià (IQS) at Barcelona. Due to the satisfactory obtained results, amperometric configuration was also evaluated. The probes are based on solid state electrolytes and are considered Proton Exchange Membranes—PEM. These electrolytes are perovskite type materials with electrical carriers being: positive holes, excess electrons, oxide ion vacancies and interstitial protons which interact with oxide ions.In the present work, solid state electrolytes for potentiometric sensors have been synthesized in order to be tested as PEM in amperometric H-probes. Amperometric measurements have been performed at different hydrogen partial pressures (5 to 55mbar), different temperatures (500°C to 650°C) and applying different polarization potentials to the sensor.

Electrodeposition and characterization of palladium nanostructures on stainless steel and application as hydrogen sensor

Palladium nanostructures have been deposited onto the stainless steel electrode by simple electrochemical deposition method in a buffer solution. The morphology of the synthesized Pd nanoparticles is controllable by deposition potentials because the driving force for various crystal growth mechanisms is merely dependent on applied potentials. The deposited Pd nanoparticles at higher applied potentials showed a cauliflower-like morphology with a nanoscale structure and large surface area. Then, an amperometric hydrogen sensor based on Pd nanoparticles can be constructed. This sensor is based on polymer electrolyte membrane fuel cell (PEMFC) and can be used at the ambient temperature. It is operated in the three-electrode mode that consists of three electrodes (working, counter and reference) and protonated Nafion membrane as proton conducting solid polymer electrolyte (SPE). The steady-state current response is obtained linearly to the concentrations of hydrogen from 50 to 2000 ppm, when a fixed potential of 0.2V is applied to the sensor. Typical factors that influence the performance of the sensor are analyzed and discussed. The simple and inexpensive hydrogen sensor fabricated shows low LOD (10 ppm, based on S/N = 3), wide linear range (50-2000 ppm) and short response time (10-40 s).

Performance of Amperometric and Potentiometric Hydrogen Sensors

The principle, design, construction and performance of the amperometric and potentiometric sensors for measuring the permeation rate of hydrogen through the wall of metal equipment were investigated in order to develop a new type of hydrogen sensor with high accuracy. The transient curves of hydrogen permeation under a given charging condition were employed to evaluate the performance of two types of hydrogen sensors. The relative deviation of the hydrogen concentration detected with two types of sensors under the same condition varied from 3.0% to 13%. The accuracy, response time, reproducibility, and installation were discussed and compared. Response time of the potentiometric sensor (E-sensor) was shorter than that of the amperometric sensor (I-sensor). Both types of sensors exhibited good reproducibility. Development of I-sensor composed of a kind of proton conductor adhesives or non-fluid electrolytes which contain two functions of high electrical conductivity and a strong adhesion will be a promising prospect in order to measure hydrogen permeation at high temperature.

Application of Solid oxide proton-conducting electrolytes for amperometric analysis of hydrogen in H2+N2+H2O gas mixtures

Amperometric hydrogen sensors based on proton-conducting solid electrolytes of La0.95Sr0.05YO3, CaTi0.95Sc0.05O3 and CaZr0,9Sc0.1O3 compositions are prepared and investigated in the present work. The influence of the sensor design on its own characteristics is also examined. It is shown that a solid electrolyte used in the form of discs with cavities significantly simplifies the design of this type of sensors. A sensor based on La0.95Sr0.05YO3 electrolyte with fully sealed junction between discs is suitable for the analysis of mixtures with high H2 content. It is found that by increasing H2 content from 10 to 98% the limiting current increases from 0.25 to 2.25mA (at 750mV). It is also found that the sensor based on La0.95Sr0.05YO3 with discs sealed in two points as well as the sensor based on CaZr0,9Sc0.1O3 with fully sealed junction are suitable for the analysis of mixtures with low H2 content (0.5-2%). For the above cases, the limiting current at 2% H2 reaches 3.5 and 0.5mA (at 750mV), respectively. CaTi0.95Sc0.05O3 is not suitable to be used as a hydrogen sensor. In all the examined systems, steam content does not affect sensors’ behavior and high operating temperatures (850°C) increase the range of sensors’ hydrogen measuring concentration capacity.

Proton exchange membrane based hydrogen sensor for sodium cleaning application

Sodium is used as coolant in fast reactors. Sodium adhering to the reactor components is required to be removed before commencement of maintenance activities. In water vapour–carbon dioxide process, sodium is removed from the components by reacting it with water vapour carried by gaseous carbon dioxide. Hydrogen is formed during the above process. Since hydrogen forms an explosive mixture with air beyond explosion limit of 4%, monitoring hydrogen in carbon dioxide is required before being let out to the atmosphere. Quantification of hydrogen also gives an estimate on the progress of the cleaning process. A fuel cell based amperometric hydrogen sensor, H2/Pt//Nafion//Pt/O2, has been developed and applied for the purpose. The paper discusses the details of the sensor, its response behavior for hydrogen in carbon dioxide and its application for hydrogen monitoring in a simulated lab scale sodium cleaning experiment. The paper also illustrates the application of the sensor to hydrogen monitoring in mock up studies on sodium cleaning of a major component of Prototype Fast Breeder reactor (PFBR) namely Failed Fuel Location Module (FFLM).

Fast escape of hydrogen from gas cavities around corroding magnesium implants

Magnesium materials are of increasing interest in the development of biodegradable implants as they exhibit properties that make them promising candidates. However, the formation of gas cavities after implantation of magnesium alloys has been widely reported in the literature. The composition of the gas and the concentration of its components in these cavities are not known as only a few studies using non-specific techniques were done about 60years ago. Currently many researchers assume that these cavities contain primarily hydrogen because it is a product of magnesium corrosion in aqueous media. In order to clearly answer this question we implanted rare earth-containing magnesium alloy disks in mice and determined the concentration of hydrogen gas for up to 10days using an amperometric hydrogen sensor and mass spectrometric measurements. We were able to directly monitor the hydrogen concentration over a period of 10days and show that the gas cavities contained only a low concentration of hydrogen gas, even shortly after formation of the cavities. This means that hydrogen must be exchanged very quickly after implantation. To confirm these results hydrogen gas was directly injected subcutaneously. Most of the hydrogen gas was found to exchange within 1h after injection. Overall, our results disprove the common misbelief that these cavities mainly contain hydrogen and show how quickly this gas is exchanged with the surrounding tissue.

A novel amperometric hydrogen sensor based on nano-structured ZnO sensing electrode and CaZr0.9In0.1O3−δ electrolyte

Abstract An amperometric hydrogen sensor using nano-structured ZnO as sensing electrode (SE) and CaZr 0.9 In 0.1 O 3− δ a proton conductor as electrolyte was fabricated. A bilayer CaZr 0.9 In 0.1 O 3− δ electrolyte including both a dense layer and a porous layer was prepared by conventional solid state reaction method. During the preparation of electrolyte, sintering aid (ZnO) was introduced into CaZr 0.9 In 0.1 O 3− δ for promoting its sintering. The ZnO-SE particles were in situ prepared in the porous CaZr 0.9 In 0.1 O 3− δ backbone by impregnating method. The composition and microstructure of the sensor were characterized by XRD and SEM, respectively. The properties of the sensor for monitoring hydrogen were studied. The results showed that a dense CaZr 0.9 In 0.1 O 3− δ electrolyte with good stability was prepared at 1350 °C. The ZnO-SE particles with diameters of 200 nm were homogeneously dispersed in the porous CaZr 0.9 In 0.1 O 3− δ backbone. The response current of the sensor was almost linear to H 2 concentration in the range of 50–500 ppm. With the temperature increasing, the sensitivity increased and reached 179.87 nA/ppm at 700 °C. The sensor showed fast response/recovery, good reproducibility, and stability.

Determination of the extent of reduction of dense UO2 cathodes from direct electrochemical reduction studies in molten chloride medium

Electro-reduction of solid UO2 to U has been studied with molten CaCl2 or LiCl as the electrolyte medium. Electro-reduction of thick (>3mm), powder compacted and sintered pellets of UO2 showed incomplete reduction resulting in a mixture of uranium metal and UO2. The extent of reduction of UO2 to U was determined by employing a novel method called ‘metal estimation by hydrogen sensor (MEHS)’, in which the hydrogen evolved during the reaction of U metal in the reduced product with con. HBr was measured using an in-house developed polymer electrolyte based amperometric hydrogen sensor. The results of our investigations on incompletely reduced UO2 pellets in both CaCl2 and LiCl melts showed that the extent of reduction of different regions of the oxide pellet was different. It varied from 88.3% on the surface of the pellet as against 3.7% towards the centre bulk during electro-reduction in CaCl2 (at 1173K). The metallisation was found restricted to the surface of the pellets reduced in LiCl melt (at 923K). Electro-reduction of small chunks of UO2 pellet in CaCl2 melt resulted in products with lower extent of reduction. Based on the measurements, a probable mechanism on the propagation of reduction through the solid UO2 matrix during the electrochemical reduction process has been proposed.

Double electrolyte sensor for monitoring hydrogen permeation rate in steels

An amperometric hydrogen sensor with double electrolytes composed of a gelatiniform electrolyte and KOH solution has been developed to determine the permeation rate of hydrogen atoms in steel equipment owing to hydrogen corrosion. The gelatiniform electrolyte was made of sodium polyacrylate (PAAS), carboxyl methyl cellulose (CMC) and 0.2 mol dm −3 KOH solution. The results show that the gelatiniform electrolyte containing 50 wt.% polymers has suitable viscosity and high electrical conductivity. The consistent permeation curves were detected by the sensor of the double electrolyte and single liquid KOH electrolyte, respectively. The developed sensor has good stability and reproducibility at room temperature.

Pt nanoparticle-supported multiwall carbon nanotube electrodes for amperometric hydrogen detection

Platinum nanoparticles (Pt NPs) were grown directly on multiwall carbon nanotubes (MWNTs) using a wet chemical reduction process. Gas permeable Pt NP-supported MWNT (Pt/MWNT) electrodes were then formed on microporous PTFE membranes through the vacuum-filtration of a Pt/MWNT solution. The potential use of these electrodes in amperometric hydrogen sensor applications was assessed. Various material analysis methods such as SEM, TEM and XRD were employed in order to characterize the morphologies and microstructures of the Pt/MWNT nanocomposites. The electrodes exhibited a nanoporous interwoven surface morphology as a result of Pt agglomerates attached to the MWNTs. From the XRD and TEM measurements, individual polygonal Pt NPs were confirmed to have polycrystalline face-centered cubic (fcc) structures and very small particle sizes of 2–7 nm. The electrode fabrication process was sequentially optimized by adjusting the MWNT content, H 2PtCl 6 concentration, NaBH 4 concentration, and the drying temperature. At optimized conditions, the Pt/MWNT electrode displayed a high sensitivity greater than 200 μA/ppm, a fairly good selectivity to interfering CO species, and an excellent linear response over the wide concentration range of 5–1000 ppm. Furthermore, the performances of the electrodes were found to be better than those of binary NP-supported MWNT systems (Pt–Pd/MWNT, Pt–Zn/MWNT, Pt–Ni/MWNT and Pt–ZnO/MWNT).

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

A novel amperometric sensor for hydrogen determination based on the PtxPdy/Nafion electrode has been developed. Bimetallic electrodes containing various compositions of PtxPdy deposited on Nafion were prepared by the Takenaka–Torikai (T–T) method. The structures and bimetallic compositions of the PtxPdy/Nafion electrodes were characterized using energy dispersive X-ray spectrometry and X-ray diffraction microscopy, respectively. Cyclic voltammograms and amperometric methods were used to evaluate the electrocatalytic activities of the prepared electrodes towards hydrogen oxidation. All the PtxPdy/Nafion electrodes fabricated had a linear relationship between response current and hydrogen concentration in the detection range from 100 to 1000ppm. The Pt22Pd78/Nafion electrode exhibited a much higher sensitivity and selectivity toward hydrogen, than it did towards nitrogen monoxide or carbon monoxide compared to the Pt/Nafion and Pd/Nafion electrodes. This bimetallic electrode also displays the shortest response and recovery times in sensing hydrogen.