Hydrogen Sensor Research Articles

High response and moisture resistance hydrogen sensors based on sandwich-structured PtSnx-rGO-SnO2 nanocomposites

Currently, semiconductor sensors typically require high operating temperatures (>200 °C) to detect H2, which increases energy consumption and safety hazards. This work uses PtSnx to modify rGO-SnO2 nanocomposites to reduce the operating temperature and improve moisture resistance. PtSnx-rGO-SnO2 nanocomposites are synthesized by a simple reflow reaction and have ppm-level H2 sensing performance at 175 °C with good moisture resistance. The PtSnx-rGO-SnO2 nanocomposite has a thickness of ~20 nm. Spherical PtSnx nanoparticles and capsule-shaped SnO2 nanoparticles were grown on the rGO surface. The spherical PtSnx nanoparticles are ~15 nm in diameter and the capsule-shaped SnO2 nanoparticles are ~5 nm in diameter and ~10 nm in length. The phase of PtSnx intermetallic compound varied as the Pt/Sn molar ratio increases. The 0.5 % PtSn2-rGO-SnO2 nanocomposites exhibited the highest response of 20.25 to 500 ppm H2 at the optimal operating temperature of 175 °C with a short response/recovery times of 1 s/17 s. The 0.5 % PtSn2-rGO-SnO2 nanocomposites also had excellent moisture resistance, reproducibility, and long-term stability. This work reveals that PtSnx-rGO-SnO2 nanocomposites are a promising sensing material for high-performance H2 detection.

A comparative study on the hydrogen dissolution and release behaviors in the zirconate proton conductors by TDS and TMAP4 analysis

Proton-conducting oxides are potential materials for electrochemical devices such as fuel cells, hydrogen pumps, hydrogen sensors, and the tritium purification and recovery system in nuclear fusion reactors. The hydrogen concentration in oxide materials is important, but its precise measurement is difficult. In this study, thermal desorption spectroscopy (TDS) was used to investigate hydrogen dissolution and release behavior in proton-conducting oxides, yttrium (Y), and cobalt (Co) doped barium-zirconates in the temperature range of 673-1273 K using deuterium (D2) and heavy water (D2O). Specimens were prepared with conventional powder metallurgy: the powder of three zirconates, BaZr0.9Y0.1O3-a (BZY), BaZr0.955Y0.03Co0.015O3-a (BZYC), and CaZr0.9In0.1O2.95 (CZI) was pressed into discs and fired in the air at 1873 K for 20 h. The densities of the sintered BZY, BZYC, and CZI specimens were 98 percent, 99.7 percent, and 99.5 percent of the theoretical densities respectively. XRD, SEM, and EDX were performed for the structural and morphological analysis of the sintered samples. From TDS measurement, a similar trend of temperature-dependent hydrogen solubility was obtained for all samples compared to the tritium imaging plate (TIP) methods literature data of HT- and DTO-exposed samples. To compare the experimental results of the deuterium desorption profile derived by TDS analysis, the simulation code of the tritium migration analysis program, version 4 (TMAP4) was employed.

Electrochemical hydrogen detection in DONES loop materials

• Design of an electrochemical sensor adequate to RAMI conditions of IFMIF-DONES. • Determination of hydrogen in liquid lithium. • Online electrochemical muliplex monitoring. • Modular design for different extended approaches (impurities, electrochemical procedures, sizes). The radiation-induced degradation of materials in fusion systems is planned to be investigated in IFMIF-DONES ( International Fusion Materials Irradiation Facility - DEMO Oriented NEutron Source ), where fast neutrons are produced by a reaction of deuteron-beams with a liquid lithium target. A by-product as critical impurity is hydrogen, which might affect the reliable and safe operation of the IFMIF-DONES loops. Therefore, an important issue is the measurement and control of the hydrogen impurity concentrations in liquid lithium. Initially, a practically applicable direct measurement of hydrogen concentrations in lithium facilities did not exist. However, one promising approach to manage this issue is based on the electrochemistry of the DONES materials The developed Electro-Chemical Hydrogen Sensor for Liquid Lithium (ECHSLL) allows the measurement of the electromotive Force (EMF) between a reference materials system and the loop lithium melt, and thus the monitoring of the hydrogen impurity concentrations. This article will show backgrounds of non-metallic impurities in liquid metal materials and the specific material stabilities within DONES. Liquid lithium is a very reactive material. Therefore critical issuesareviable materials compatibilities, the interactions with hydrogen and the transport behaviour of H-ions in electrolytes at the applied temperatures. Further issues are also the syntheses of the electrochemical materials, as hydrogen conducting electrolytes, reference electrode systems and the different procedures (heat treatments and conditioning steps). The tests showed the functionality of the developed H-sensor. Beyond that, the used material combinations exhibited reliable behaviour in melts under harsh conditions. Hence, the most critical aspect (stability of the sensor materials in the Li-melt) has been resolved by using niobium sensor heads. The observed experimental EMF potentials are in good accordance compared with calculated models, also in long-time experiments.

Pd Nanoparticle/Pd/Al2O3 Resistive Sensor for Hydrogen Detection in a High-Temperature Environment

An Al2O3 thin film is deposited on the interdigitated electrodes to fabricate a resistive hydrogen sensor. In addition, the Pd nanoparticles (NPs)/Pd film by vacuum thermal evaporation system on the Al2O3 film acts as catalytic metals for hydrogen detection. Due to the Pd NPs with an increased surface area to volume ratio as well as the spill-over effect, the catalytic activity could be improved to enhance the gas sensing performance. The experimental results showed that the sensing response ratio is 14.4% in 1000 ppm H2/air at 300 °C, which is suitable for high-temperature hydrogen detection. The studied Pd NPs/Pd/Al2O3 resistive sensor exhibits the advantages of in high-temperature operation, simple structure, easy fabrication process, and relatively low cost.

Synthesis and analysis of TiO2 nanotubes by electrochemical anodization and machine learning method for hydrogen sensors

The conductometric hydrogen gas sensors were used to explore TiO2 nanotubes in this study. TiO2 nanotubes are synthesized by anodization of the titanium foils using a neutral 0.5% and 1% (wt) NH4F in glycerol solution depending on anodization time and anodization voltage at the temperature of 20 °C. The amorphous, rutile and anatase phases of TiO2 are observed for as-prepared TiO2 nanotubes, annealed at 700 and 300 °C, respectively. The diameters of the nanotubes grow as the anodization time and voltage increase, according to scanning electron microscopy (SEM) images. The inner diameter of nanotubes is changed between ~70 nm to ~225 nm. Hydrogen sensing properties of Ti/TiO2 nanotubes/Pd device has been tested at room temperature under concertation range from 0.5% to 10% depending on the crystalline phase. The highest sensor response is observed for anatase crystalline TiO2 nanotubes. Typical Schottky-type behavior is observed from the I-V measurement. All the fabricated nanotube diameters are also simulated by using Support Vector Machine and Artificial Neural Network models. And also, some of the nanotube diameters which are not obtained experimentally (anodization voltage of 70 V) are estimated using the Support Vector Machine and Artificial Neural Network models. In addition, an analytical model is also proposed using Jacobi numeric analysis method alternative to the simulation model for the nanotube diameter. Finally, the analytical, simulation, and experimental results are compared, and the best result is obtained using the 1 Hidden Layer Artificial Neural Network model.

Optical Fiber Hydrogen Sensor Based on the EVA/Pd Coated Hollow Fiber

A novel optical fiber hydrogen sensor based on the dielectric/metal coated hollow fiber structure is proposed. The palladium (Pd) and ethylene-vinyl acetate (EVA) layers are sequentially coated on the inner surface of the hollow core of the silica capillary to fabricate the EVA/Pd coated hollow fiber sensor. Theoretical ray transmission model is carried out to analyze the influence of the thicknesses of the Pd and EVA films. The experimental transmission spectra of the proposed sensor filled with hydrogen gas of different concentrations are measured. The experimental results show that the interference peak in the spectrum has a red shift with the increase of hydrogen concentration. Then the hydrogen concentration can be obtained by measuring the wavelength of the interference peak. In the range of 0–4% hydrogen concentration, the total shift is 10.64nm and the average sensitivity is 2.66 nm/%. Compared to other optical fiber hydrogen sensors, the proposed sensor has the advantages of simple structure, easy fabrication, low cost, high sensitivity and good safety performance.

Low-temperature hydrogen sensor based on sputtered tin dioxide nanostructures through slow deposition rate

In this paper, tin dioxide (SnO2) mesoporous nanostructures (pores of 2 and 50 nm) were directly sputtered on a Pt-interdigitated electrode (gap length of 35 μm) with a slow deposition rate of 5 nm/min under a controlled substrate temperature of 100, 350, and 500 °C. It is found that the surface area was 0.22 × 104, 0.18 × 104, and 0.17 × 104 observed for the nanostructure prepared at 350 °C, 500 °C, and 100 °C, respectively. The film crystallinity increased with increasing the substrate temperature. The film prepared at 500 °C showed a lower resistivity in air. Most importantly, the sensor fabricated by using the nanostructure prepared at 500 °C exhibits excellent low-temperature (100 °C) H2 sensing properties. When this sensor is exposed to 1000 ppm (0.1%) H2, the sensor response is 30 × 103 %. The sensing performances are superior to those of most reported at higher temperature H2 sensors based on SnO2 materials. Interesting is the sensor selectivity, where the sensor prepared at 500 °C is selective toward H2 gas, while the sensor prepared at 350 °C is selective toward NO2 gas. The sensing performance of the sensor prepared at 500 °C for H2 (reducing gas) was attributed to a proposed mechanism of a coulomb interaction (electric dipole). The sensors exhibit two different behaviors of their electrical resistivities upon exposure to H2 gas at low and high temperatures. The gas sensing mechanisms for such behaviors were proposed to understand the sensor behavior. The current results may assist in realizing high selective sensors toward H2 for the commercial market.

ИССЛЕДОВАНИЕ ЧУВСТВИТЕЛЬНОСТИ И СЕЛЕКТИВНОСТИ ТЕРМОКАТАЛИТИЧЕСКОГО СЕНСОРА ВОДОРОДА

The study demonstrates for the first time the high selectivity of catalytic hydrogen sensors to other hydrocarbons (methane, propane, hexane, butane, ethane and ethylene) at an operating temperature less than 70 ºС. Two circuits were used to measure the response of sensors: a Wheatstone bridge circuit and a divider circuit. The hydrogen measurement was conducted at the temperatures ranging from 66 to130 ºС. It is shown that the sensors have a high sensitivity of 25–35 mV/% and a low power consumption of approximately 8.6 mW. The Wheatstone bridge circuit was observed to have the maximum value of selectivity and sensitivity.

Fast, Sensitive, and Highly Selective Room-Temperature Hydrogen Sensing of Defect-Rich Orthorhombic Nb2O5-x Nanobelts with an Abnormal p-Type Sensor Response.

The research and development of low-power-consumption and room-temperature hydrogen sensors are of great significance for the safe application of hydrogen energy. Herein, orthorhombic Nb2O5-x nanobelts are prepared through a combined procedure of hydrothermal, ion exchange, and annealing treatment in Ar. The topological transformation process results in the formation of abundant surface defects including chemical defects such as Nb4+, oxygen vacancies, and disordered microregions, which lead to the abnormal p-type conducting and hydrogen sensing behavior. Moreover, the orthorhombic Nb2O5-x nanobelts exhibit fast and sensitive room-temperature hydrogen sensing performance, which shows greater advancement than the monoclinic, tetragonal, and hexagonal Nb2O5 one-dimensional (1D) nanostructures. The response time and lowest limit of detection of the as-fabricated room-temperature sensor decrease to 28 s and 3.5 ppm, respectively. The sensor also exhibits a highly selective hydrogen response against CO, CH4, ethanol, H2S, and NH3. The hydrogen response of the Nb2O5-x nanobelts can be attributed to the redox reaction between hydrogen and preadsorbed oxygens. The defective surface structure and the prolonged dimension of the nanobelts give rise to the highly reactive surface and the suppression of the negative nanojunction effect, which greatly improves the sensing performance. The orthorhombic lattice structure can also promote gas adsorption and diffusion behavior due to its specific catalytic and pathway effect. The results of this work can be helpful for the rational design and defect engineering of the Nb2O5-based 1D nanostructures for room-temperature hydrogen sensing applications.

ВИКОРИСТАННЯ ВОДНЯ В ЕНЕРГЕТИЦІ

As a result of the conducted literature research the experimentally fixed positions about features of the hydrogen-induced deformation of a palladium plate are described. It is determined that when hydrogen saturation in the metal, a temporary gradient material "metal-hydrogen" is formed and hydrogen stress concentrations always occur. This in turn provides effective planning and determination of the time of penetration of hydrogen into the metal. The obtained experimental facts allow to control the change of shape and regulate the modes of operation of the fuel cell during the operation of the products. It is described that the maximum bending of the plate occurs at a constant temperature, and is determined by two fundamental properties of the palladium system - hydrogen, namely, the diffusion coefficient and equilibrium solubility of hydrogen in palladium. However, when the temperature changes, the diffusion coefficient of hydrogen in palladium and the equilibrium concentration of hydrogen in palladium changes, which determines the temperature dependence of the final bending of the plate and its change) when interacting with hydrogen. The scientific novelty is the use of the known material palladium, which in contact with hydrogen becomes a temporary gradient alloy with variable physical properties. It is established that the heat exchange in the plate and the energy balance around the plate depends on the rate of interaction of hydrogen and material, as well as the rate of heat flux that occurs during chemical reactions in fuel cells and heat loss in the fuel cell. The practical significance of the work lies in the possibility of using certain physical bases in practice in the manufacture of specific devices that work as a fuel cell with hydrogen. You can also model this process in MaCad and improve the operating conditions of fuel cells and hydrogen sensors, because at low temperatures there is a relatively small residual bending of the main components, and accordingly there are changes in the shape of these components.

The nanophotonic machinal cavity and its hydrogen sensing application

Hydrogen, a clean energy carrier, possesses great potential to be an alternative fuel in the future. However, it also has a reputation for being explosive and dangerous. Thus, in the realization of hydrogen energy utilization, hydrogen safe storage and transport are the main issues which currently need to be solved at present. For safety, hydrogen leaks or concentration variations should be monitored accurately and timely during storage or transport. Among the many sensors, the optical hydrogen sensor can satisfy demands of safety, online detection, undisturbed surrounding, and lack of spark. Hence, a fiber-based nanophotonic machinal cavity (NPMC) is proposed and proved that it can be used for hydrogen sensing. This cavity is composed of two mirrors: One is fiber-air interface, another is gold (Au)/palladium (Pd) hybrid nanofilm, herein, Au film with low elastic modulus is employed as a reflective mirror and support substrate of Pd component. Since Pd-hydrogen reactions can induce deformation on this hybrid nanofilm, which will change the resonant characteristics of the cavity, Pd functions as hydrogen-sensitive nanomaterial. Experimentally, Au/Pd hybrid nanofilm-based NPMCs are prepared and used to demonstrates the feasibility of hydrogen sensing. The experimental results reveal that this proposed NPMC maintains advantages of reusable, durable, fast response/recovery (12/1s), low limit of detection (0.1%) and widely linear detection range (1–3.5%) in hydrogen sensing application. This intrinsically safe, miniaturized fiber optic device can be used in space constrained and hazardous environments.

Low-Dimensional Palladium on Graphite-on-Paper Substrate for Hydrogen Sensing

To stabilize the detection signal of palladium-based hydrogen sensors on paper substrates, a graphite intermediate layer was painted on the surface of paper. The graphite-on-paper (GOP) substrate offers advantages such as good thermo-electrical conductivity, low cost, and uncomplicated preparation technology. Quasi-1-dimensional palladium (Pd) thin films with 8 nm and 60 nm thicknesses were deposited on the GOP substrates using the vacuum evaporation technique. Thanks to the unique properties of the GOP substrate, a continuous Pd microfiber network structure appeared after deposition of the ultra-thin Pd film. Additionally, the sensing performance of the palladium-based hydrogen sensor was not affected, whether using GOP or paper substrate at 25 °C. Surprisingly, heating-induced loss of sensitivity was restrained due to the increased electrical conductivity of the GOP substrate at 50 °C.

Ultrasensitive hydrogen sensor based on porous-structured Pd-decorated In2O3 nanoparticle-embedded SnO2 nanofibers

Porous-structured Pd-decorated In2O3 nanoparticle-embedded SnO2 nanofibers are synthesized by electrospinning and a thermal calcination process using hydrothermally synthesized In2O3 nanoparticles. From this process, porous nanofibers can be obtained without any ZnIn2O4 components, and the sensing performance of the nanofibers can be maximized owing to the numerous pores and grain boundaries in their body. Additionally, as Pd nanoparticles form Schottky barriers with a nanofiber body and generate a catalytic effect, the hydrogen-sensing performance of these nanofibers can be increased. However, to significantly enhance the sensing performance of low-concentration hydrogen gas, sensors with more effective structures should be proposed. Hence, the Pd-decorated In2O3 nanoparticle-embedded SnO2 porous nanofibers are synthesized in this study for improved sensing performance. The response of this heterostructured nanofiber is 1291 for 100 ppm hydrogen gas, and the nanofiber exhibits a remarkable sensing performance, which is enhanced by 24 times, compared with the Pd-decorated SnO2 nanofibers. This study provides optimum In2O3 nanoparticles with the best hydrogen sensing performance and sensing mechanisms.

Plasmonic Hydrogen Sensors

Hydrogen is regarded as the ultimate fuel and energy carrier with a high theoretical energy density and universality of sourcing. However, hydrogen is easy to leak and has a wide flammability range in air. For safely handling hydrogen, robust sensors are in high demand. Plasmonic hydrogen sensors (PHS) are attracting growing interest due to the advantages of high sensitivity, fast response speed, miniaturization, and high-degree of integration, etc. In this review, the mechanism and recent development (mainly after the year 2015) of hydrogen sensors based on plasmonic nanostructures are presented. The working principle of PHS is introduced. The sensing properties and the effects of resonance mode, configuration, material, and structure of the plasmonic nanostructures on the sensing performances are discussed. The merit and demerit of different types of plasmonic nanostructures are summarized and potential development directions are proposed. The aim of this review is not only to clarify the current strategies for PHS, but also to give a comprehensive understanding of the working principle of PHS, which may inspire more ingenious designs and execution of plasmonics for advanced hydrogen sensors.

Room temperature hydrogen sensor based on Nafion and Pd/CF sensing electrode

The development of high-performance H2 gas sensors is a challenge for safe operation in the high-risk area of flammable and explosive. In this work, Pd/CF is used as a sensing material in fuel cell type sensors and the effect of Pd loading (5 wt%, 10 wt% and 20 wt%) on the sensors’ performance is investigated. The sensor based on Pd(10 wt%)/CF shows the best sensing performance which can be attributed to both the optimal balance of Pd content and utilization to produce the most active sites for the catalytic reaction and the highest conductivity of the membrane electrode assembly (MEA). These are confirmed by EDS images, cyclic voltammetry curve and complex impedance curves. The optimal sensor has a response value of about − 60 μA to 5000 ppm H2 and a sensitivity of − 0.0131 μA/ppm to 200–10000 ppm H2 at room temperature (25 °C). In addition, with the advantages of no heating, no external voltage, simple fabrication process, high linearity, good repeatability and long-term stability, the sensor in this work possesses very broad development prospect.

Electrochemical Hydrogen Sensor Assembly for Monitoring High‐Concentration Hydrogen

The demand for hydrogen energy is rapidly increasing because of its clean, abundant, and efficient nature. To utilize hydrogen gas as a fuel for fuel‐cell vehicles, several types of hydrogen sensors are needed to address cost and safety issues. Precise monitoring of hydrogen gas concentration is critical in optimizing vehicle fuel‐cell efficiency. Herein, a fully packaged hydrogen sensor to continuously measure a hydrogen concentration of 20–100% with environmental variations is fabricated, including temperature (from −40 to 105 °C), humidity (from 10 to 98 RH%), and pressure (from 30 to 350 kPa). A signal‐processing circuit is designed to reduce the error rate, and a sensor chip and printed circuit board are assembled in a module using a packaging process with robust materials for harsh vehicle environments. The result herein suggests direct application of the sensor to monitor hydrogen concentration in the hydrogen recirculation unit in a fuel‐cell vehicle.

Development of Highly Sensitive and Stable Surface Acoustic Wave‐Based Hydrogen Sensor and Its Interface Electronics

AbstractA surface acoustic wave (SAW)‐based hydrogen sensor and its corresponding interface electronics have been developed to measure the hydrogen concentration in air at room temperature. Two SAW delay lines with center frequencies of 284 and 284.3 MHz are employed for the sensor system to eliminate any environmental disturbances emerging from temperature and humidity variations on a sensor output. A beehive‐configured and Cu‐doped SnO2 nanostructure is used as a hydrogen‐sensitive material to have a high surface to volume ratio, high sensitivity, and selectivity for the target hydrogen. The smallest frequency difference detectable in our sensor system including oscillator, mixer, low pass filter, comparator, and field programmable gate array (FPGA) was ≈1 Hz, which is a significant output value that can sufficiently detect hydrogen concentrations below 1 ppm. Compared with pure SnO2, 3D Cu (3%)‐doped SnO2 nanostructure based‐SAW sensor exhibited the highest response to hydrogen gas. The elevated response of the 3D Cu‐doped SnO2 based SAW sensor to hydrogen gas is mainly attributed to the acoustoelectric interaction. Photoluminescence and X‐ray photoelectron spectroscopy analysis divulged that Cu‐doping in SnO2 produces a large number of surface oxygen vacancies, which enhances the hydrogen adsorption on the SnO2 surface, resulting in a significant improvement in the response to hydrogen gas. The sensor characteristics at the system level showed excellent selectivity, repeatability, and long‐term stability to hydrogen gas. The sensing mechanisms (mass loading and acoustoelectric interaction) in the SAW sensor due to hydrogen adsorption have been experimentally investigated and the obtained results are discussed in detail.

Integrated CuO/Pd Nanospike Hydrogen Sensor on Silicon Substrate.

A large area of randomly distributed nanospike as nanostructured template was induced by femtosecond (fs) laser on a silicon substrate in water. Copper oxide (CuO) and palladium (Pd) heterostructured nanofilm were coated on the nanospikes by magnetron sputtering technology and vacuum thermal evaporation coating technology respectively for the construction of a p-type hydrogen sensor. Compared with the conventional gas sensor based on CuO working at high temperature, nanostructured CuO/Pd heterostructure exhibited promising detection capability to hydrogen at room temperature. The detection sensitivity to 1% H2 was 10.8%, the response time was 198 s, and the detection limit was as low as 40 ppm, presenting an important application prospect in the clean energy field. The excellent reusability and selectivity of the CuO/Pd heterostructure sensor toward H2 at room temperature were also demonstrated by a series of cyclic response characteristics. It is believed that our room-temperature hydrogen sensor fabricated with a waste-free green process, directly on silicon substrate, would greatly promote the future fabrication of a circuit-chip integrating hydrogen sensor.

Supraparticles for Bare‐Eye H2 Indication and Monitoring: Design, Working Principle, and Molecular Mobility (Adv. Funct. Mater. 22/2022)

Hydrogen Sensors In article number 2112379, Tanja Bauer, Karl Mandel, and co-workers, demonstrate micrometer-sized supraparticles for rapid real-time monitoring and irreversible recording of H2 gas via a distinct, eye-readable two-step color change. Key for the functionality is a three-phase system within the mesoporous, multi-component supraparticles. The supraparticles are an attractive safety additive for leakage detection and localization in a H2 economy.

Selective Low-Temperature Hydrogen Catalytic Sensor

The research demonstrates for the first time the high selectivity of catalytic hydrogen sensors to other hydrocarbons (methane, propane, hexane, butane, ethane, and ethylene) at a temperature less than 70 °С. Two circuits were used to measure the response of the sensors: a Wheatstone bridge circuit and a divider circuit. Hydrogen measurement was conducted within a temperature range of 66–130 °С. The sensors exhibited high sensitivity (25–35 mV/%) and low power consumption (approximately 8.6 mW). The Wheatstone bridge circuit was observed to have the maximum value of selectivity and sensitivity.