Hydrogen Gas Sensor Research Articles

Hydrogen-Sensing Properties of Ultrathin Pt-Co Alloy Films

The present work aims to investigate the feasibility of utilizing Pt and PtCo alloy ultrathin films as hydrogen gas sensors in order to reduce the cost of the hydrogen gas sensors by using low-cost metallic materials. In this study, ultrathin Pt and PtCo alloy thin films are evaluated for hydrogen sensors. The stoichiometry and structural characterization of the thin films are observed from XPS, SEM, and EDX measurements. The 2-nm-thick Pt and PtCo films deposited by sputtering onto Si/SiO2 covers homogeneously the surface in an fcc crystalline plane (111). The hydrogen gas-sensing properties of the films are assessed from the resistance measurement between 25 °C and 150 °C temperature range, under atmospheres with hydrogen concentration ranging from 10 ppm to 5%. The hydrogen-sensing mechanism of ultrathin PtxCo1-x alloy films can be elucidated with the surface scattering phenomenon. PtCo thin alloy films show better response time than pure Pt thin films, but the alloy films show lower sensor response than pure Pt film’s sensor response. Aside from these experimental investigations, first-principles calculations have also been carried out for bare Pt and Co, and also PtCo alloys. Compared to the theoretical calculations, the sensor response to change decreases with increasing Co content, a result that is compatible with the experimental results. In an attempt to explain the decrease in the sensor response of PtCo alloy films compared to bare Pt film, a variety of different phenomena are discussed, including the shrinking lattice of the structure or dendritic surface structure of PtCo alloy films by the increasing cobalt ratio.

Palladium-based Electrical and Optical Hydrogen Gas Sensors

Palladium-based Electrical and Optical Hydrogen Gas Sensors

Improvement of hydrogen detection sensitivity of palladium film by in-plane compressive plastic deformation and application to hydrogen gas sensor

The hydrogen energy, which is environmentally friendly and does not emit carbon dioxide, has been attracting attention as an alternative fuel to the fossil fuel. In the shift to a hydrogen energy society, the highly sensitive hydrogen gas sensor has been required for the storage and management of hydrogen gas. In this study, we propose a film deposition method to induce the in-plane plastic deformation in the thin film and apply it to a hydrogen gas sensor, where the palladium film formed by this method is deposited on a thin quartz resonator. It is found that the sensor chip with the plastically deformed palladium film is about 1.5 times more sensitive than the conventional sensor chip and has high-speed response. The developed sensor is a novel device that can be used in an oxygen-free environment without any temperature compensation and constant heating.

Palladium/Graphene Oxide Nanocomposite for Hydrogen Gas Sensing Applications Based on Tapered Optical Fiber.

Gaseous pollutants such as hydrogen gas (H2) are emitted in daily human activities. They have been massively studied owing to their high explosivity and widespread usage in many domains. The current research is designed to analyse optical fiber-based H2 gas sensors by incorporating palladium/graphene oxide (Pd/GO) nanocomposite coating as sensing layers. The fabricated multimode silica fiber (MMF) sensors were used as a transducing platform. The tapering process is essential to improve the sensitivity to the environment through the interaction of the evanescent field over the area of the tapered surface area. Several characterization methods including FESEM, EDX, AFM, and XRD were adopted to examine the structure properties of the materials and achieve more understandable facts about their functional performance of the optical sensor. Characterisation results demonstrated structures with a higher surface for analyte gas reaction to the optical sensor performance. Results indicated an observed increment in the Pd/GO nanocomposite-based sensor responses subjected to the H2 concentrations increased from 0.125% to 2.00%. The achieved sensitivities were 33.22/vol% with a response time of 48 s and recovery time of 7 min. The developed optical fiber sensors achieved excellent selectivity and stability toward H2 gas upon exposure to other gases such as ammonia and methane.

Optimization of Pt nanoparticles loading in ZnO for highly selective and stable hydrogen gas sensor at reduced working temperature

The aim of the current research is to utilize pure ZnO, and Pt nanoparticles loaded ZnO pencil-like microstructures to develop a highly selective and stable H2 gas sensor. The microstructures were synthesized using the well-known hydrothermal route and characterized via several techniques such as X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy to investigate the structural, elemental, and morphological properties. Finally, the hydrogen sensing properties of prepared sensors were examined to optimize the Pt content and explore the detection capabilities of the materials toward H2 gas. The highly selective response was observed for the optimum concentration of 1 at% Pt loaded ZnO microstructures at a relatively reduced working temperature of 150 ℃ with good repeatability and high stability. Additionally, the improved sensing mechanism was thoroughly investigated. Our findings indicate that the inclusion of an optimal amount of noble metals into metal oxide semiconductor-based microstructures improves the gas detection performance with superior selectivity in real-world applications.

Room-temperature hydrogen gas sensor composed of palladium thin film deposited on NiCo2O4 nanoneedle forest

This paper reports the performance and fabrication method of a palladium (Pd) gas sensor with a NiCo2O4 nanoneedle forest (NNF) that is very sensitive to hydrogen (H2). The Pd surface area that could react with H2 was maximized by sputtering Pd on NiCo2O4 NNF, which resulted in excellent sensitivity and response speed. Also, the temperature sensor and heater are integrated by using microelectromechanical system (MEMS) processes, where the sensitivity, as well as the response and recovery speeds, can be adjusted by controlling the operation temperature. The proposed sensor showed relative resistance changes of at RT and at 300 °C when saturated with a H2 concentration of 300 ppm. The response times were as fast as 117 and 102 s at RT for the rising and recovering cycles, respectively. However, at 300 °C, the response times in the rising and recovery cycles were 26 and 23 s, respectively, which were faster than those at RT. The sensor response at RT was linear throughout the measurement range, with a sensitivity of and a detection limit of 28 ppb. Therefore, the proposed sensor can be used as a low-power, high-sensitivity sensor at RT or as a sensor with a fast response time at a high operating temperature using an integrated heater.

Preparation and Characterization of Different Concentrations of Palladium-Loaded Graphitic Carbon Nitride-Based Nanocomposites as an Efficient Hydrogen Gas Sensor at Room Temperature

Preparation and Characterization of Different Concentrations of Palladium-Loaded Graphitic Carbon Nitride-Based Nanocomposites as an Efficient Hydrogen Gas Sensor at Room Temperature

Introducing oxygen vacancies on sodium titanate via NaBH4 treatment for conductometric hydrogen gas sensors

Sodium titanate (NTO) has drawn great attentions in various applications, but few works focus on using NTO as gas sensors. The implication of NTO as gas sensors requires a simple synthesis route to fabricate NTO with large surface areas and oxygen vacancies. Herein, Pd-decorated NTO microscale hierarchical spheres (Pd-NTO MHSs) is synthesized using Ti foil as a precursor·H2O2 is added to promote the preparation of NTO MHSs under a low base-concentration and low temperature condition, making the synthetic route more eco-friendly than previously methods. Additionally, we demonstrate NaBH4 reduction is a one-step process that simultaneously decorates Pd nanoparticles and brings abundant oxygen vacancies on the NTO surface, but too high NaBH4 concentration deteriorates the hydrogen sensing performance. At the optimized condition, Pd-NTO MHSs have a response time of ∼1.8 s to 1% H2 and a wide detection range of 10 ppm to 10% H2 at 25 °C. This study highlights that NaBH4 treatment is an effective strategy for regulating surface chemical properties and introducing oxygen vacancy on NTO, enabling Pd-NTO MHSs an excellent sensing property. It is also helpful for the rational design of NTO as a versatile sensing material with abundant oxygen vacancies to sense other gases.

Formation of palladium nano-gap on self-cracked WO3 for hydrogen gas sensors

In the event of a hydrogen leak accident, an explosion occurs at a concentration of 4% or more in the atmosphere, so, the technology to accurately measure the hydrogen detection near the 5% area is very important. Among the various hydrogen detection methods, a hydrogen sensor using a fine pattern of Pd with excellent ability to absorb hydrogen is very suitable for this purpose. In this study, in forming a micropattern of Pd metal, a technique for easily fabricating Pd micropatterns was proposed by utilizing micro-cracks generated in the process of forming a ceramic thin film on a polymer substrate. It showed very accurate detection capability at the 1–5% hydrogen concentration level, and it is expected that it can be easily applied to various curvature environments as it is manufactured on a polymer substrate.

Effect of substrate bending towards chemiresistive based hydrogen gas sensor using ZnO-decorated MgO nanocubes

In this report, a flexible ZnO-decorated MgO nanocubes and core shell type of ZnO/MgO nanocomposite were prepared and used for sensing of hydrogen gas by chemiresistive technique. The preparation of ZnO-decorated MgO nanocubes and core shell type of ZnO/MgO composite was done by two process—chemical vapor deposition followed by drop casting method. Initially, the MgO nanocubes were prepared by chemical vapor deposition methods and then a decoration or creation of shell layer on the surface of MgO nanocubes was optimized by the variation of Zn precursor (1 mol–3 mol of Zinc acetate dehydrate) during the drop-coating process. The prepared ZnO/MgO composite was characterized using scanning electron microscope, energy-dispersive X-ray analysis, X-ray diffraction, and Fourier transform infrared spece. From this characterization, a one mol of Zn precursor leads to the decoration of ZnO nanoparticle (∼100 nm) on the surface of nanocubes. For the 2 mol concentration, the size of ZnO nanoparticle increases from ∼100 nm to ∼200 nm. By further increasing the molar concentration of Zn precursor from 2 to 3 mol, the coverage of nanoparticle increases and creates the shell on the core of MgO nanocubes. Therefore, tuning the Zn precursor leads to two different form of composite such as ZnO-decorated MgO nanocubes (1 and 2 mol) and core-shell type of ZnO/MgO nanocomposite (3 mol). The prepared composite was deposited on flexible substrate by doctor blade method and then used for studying H2 sensing response by chemiresistive method. A maximum response was achieved for 1 mol ZnO/MgO composite (Sensitivity = 1.1459) compared to other concentration (sensitivity of 0 mol–1.0858, 2 mol–1.06 and 3 mol- 1.02) due to the heterojunction formation as well as spillover effect. Further, the flexibility of prepared sensor was studied by varing the bending angle of substrate. From these analysis, the prepared ZnO-decorated MgO nanocubes are well suitable for flexible hydrogen sensor.

First principles study of Rh-doped SnO2 for highly sensitive and selective hydrogen detection

Tin dioxide is a low-cost and efficient material with large potential in applications of hydrogen detection. Doping metals in SnO2 is a solution to further improve its electrical performance, however, atomic-scale understanding of detection mechanism of doped SnO2 is very limited. In this work, first principles and molecular dynamics method are applied to investigate adsorption properties and diffusion effects of CH4, CO2, H2, N2 on Rh-doped SnO2. By calculating adsorption energy, adsorption distance, charge density difference, density of states, it is concluded that Rh-SnO2 shows a strong sensing characteristics towards H2, which is consistent with experiment result. After adsorption of H2, the main energy bands of DOS shift to a lower level of energy, and the Fermi level move to higher level of energy. H2 shows a strong chemical adsorption effect on Rh-SnO2, while CH4, CO2 and N2 only present weak physical adsorption on Rh-SnO2. Furthermore, the diffusion of H2 in Rh-SnO2 is easier than those of other gases. Our study provides a fundamental and new perspective for designing highly sensitive hydrogen gas sensor from atomic and electronic level.

Metal Organic Framework-Derived ZnO@GC Nanoarchitecture as an Effective Hydrogen Gas Sensor with Improved Selectivity and Gas Response

Although they are not as favorable as other influential gas sensors, metal-oxide semiconductor-based chemiresistors ensure minimal surface reactivity, restricting their gas selectivity, gas response, and reaction kinetics, particularly when functioning at room temperature (RT). A hybrid design, which includes metal-oxide/carbon nanostructures and passivation with specific gas filtration layers, can address the concerns of surface reactivity. We present a novel hierarchical nanostructured zinc oxide (ZnO), decorated with graphitic carbon (GC) and synthesized via a wet-chemical strategy, which is then followed by the self-assembly of a zeolitic imidazolate framework (ZIF-8). Because of its large surface area, high porosity, and efficient inspection of other analyte (interfering) gases, the ZnO@GC can provide intensified surface reactivity at RT. In the present study, such a hybrid sensor confirmed extraordinary gas sensing properties, which was characterized by excellent H2 selectivity, fast response, rapid recovery kinetics, and high gas response (ΔR/R0 ∼ 124.6%@10 ppm), particularly in extremely humid environments. The results reveal that adsorption sites provided by the ZIF-8 template-based ZnO@GC frameworks facilitate the adsorption and desorption of H2.

Design and Investigation of Double Gate Field Effect Transistor Based H2 Gas Sensor Using Ultra-Thin Molybdenum Disulfide

In this article, a low-power hydrogen (H2) gas sensor has been proposed using a two-dimensional (2D) material based Double Gate Field Effect Transistor (2D-FET). It is imperative to highlight that the conventional three-dimensional (3D) materials cannot be scaled down to an ultra-low dimension due to the presence of dangling bonds, surface roughness scattering etc. This creates a major challenge in developing low-dimensional sensors for next generation sensing and computing. In this context, we have developed an extensive simulation model, which articulates the physical phenomena behind a catalytic metal gate-based hydrogen gas sensor using a 2D-FET. A 5 nm thin Molybdenum disulfide (MoS2) film has been used as the channel material for the proposed 2D-FET based gas sensor. The sensor has been modelled by emphasizing on the catalytic metal (Palladium) gate approach, where the work function of the gate metal deposited on top of the channel region varies after the absorption of the hydrogen gas. Moreover, the Technology Computer Aided Design (TCAD) based gas sensor model has been developed by considering a change in the pressure of H2 gas as well. We have also highlighted the effect of Metal/MoS2 contact on sensor performance. In terms of the performance, a maximum threshold voltage (Vth) shift of 100 mV has been obtained against a gas pressure of 10−10 torr, whereas the maximum percentage of change in ION/IOFF is 100. Lastly, the authors have shown the thermal noise characteristics of the gas sensor.

A resonant photoacoustic cell for hydrogen gas detection

Hydrogen gas (H2) detection plays an important role in many fields. With the continuous demand and development of clean energy, it is urgent to study new hydrogen gas sensors for stable and accurate H2 detection. The purpose of this research is to develop a new H2 sensor based on the resonant photoacoustic (PA) cell as the sensing element. The sensitivity of the resonant PA cell to the resonant frequency is sufficiently utilized. The optimization of its resonance frequency was investigated minutely for the H2 sensor. Detection utilizes resonance frequency differences between H2 and air as a sensing mechanism. The resonance frequency tracking is adopted and implemented by the field-programmable gate array (FPGA) device. The minimum detection limit of about 74 ppm for H2 has been demonstrated by preliminary experiments. The response time of the sensor is about 5 s. This sensor detects concentrations ranging from 74 ppm to 100% in 1 atm. The preliminary test result shows that the H2 sensor based on this structure has a larger application perspective.

Fabrication and characterization of a highly sensitive hydrogen gas sensor

A rapidly growing world where sources are decreasing mmoneoney, time causes a big problem for some region. Contaminations get expanding step by step because of the contamination and waste that comes from businesses in light of petroleum derivative. To diminish the utilization of petroleum products around then a characteristic wellspring of energy went about as a deliverer which was not just utilized as a perfect wellspring of energy yet in addition utilized in different fuel and modern cycles. Such gas is hydrogen gas which is the most ideal decision likewise universally acknowledged and present in bounty sum. Yet, hydrogen gas is exceptionally combustible and as its particles are minuscule in size, its scentless, vapid property makes it hard to perceive and recognize effectively in the event that any measure of gas is releasing, such little leakage can bring about a major debacle and its impact stay for a significant stretch. To forestall and recognize such leakage and mishap a sensor should be planned and creation is fundamental. This paper talks about different materials, strategies, and cycles expected to make a viable detecting gadget. Likewise, the entire cycle stream and other plan boundaries are examined with an alternate writing review of paper to make a powerful and valuable sensor for the identification of Hydrogen gas.

Nanosensors Based on a Single ZnO:Eu Nanowire for Hydrogen Gas Sensing.

Fast detection of hydrogen gas leakage or its release in different environments, especially in large electric vehicle batteries, is a major challenge for sensing applications. In this study, the morphological, structural, chemical, optical, and electronic characterizations of ZnO:Eu nanowire arrays are reported and discussed in detail. In particular, the influence of different Eu concentrations during electrochemical deposition was investigated together with the sensing properties and mechanism. Surprisingly, by using only 10 μM Eu ions during deposition, the value of the gas response increased by a factor of nearly 130 compared to an undoped ZnO nanowire and we found an H2 gas response of ∼7860 for a single ZnO:Eu nanowire device. Further, the synthesized nanowire sensors were tested with ultraviolet (UV) light and a range of test gases, showing a UV responsiveness of ∼12.8 and a good selectivity to 100 ppm H2 gas. A dual-mode nanosensor is shown to detect UV/H2 gas simultaneously for selective detection of H2 during UV irradiation and its effect on the sensing mechanism. The nanowire sensing approach here demonstrates the feasibility of using such small devices to detect hydrogen leaks in harsh, small-scale environments, for example, stacked battery packs in mobile applications. In addition, the results obtained are supported through density functional theory-based simulations, which highlight the importance of rare earth nanoparticles on the oxide surface for improved sensitivity and selectivity of gas sensors, even at room temperature, thereby allowing, for instance, lower power consumption and denser deployment.

Extremely simple structure hydrogen gas sensor based on single metallic thin-wire under sweep heating

We here propose a sweep heating of a single metallic thin-wire for thermal conductivity detector (TCD)-based gas sensor. Owing to the sweep heating, much information can be acquired compared with the typical heating. Accordingly, even though the sensing element is only the single metallic thin-wire, it can detect hydrogen without the compensator. After the simple mathematical operation, the relation between input power (P) and resistance (R), namely P-R diagram, can be calculated and it depicts a change in thermal conductivity of surrounding gas clearly. Indeed, hydrogen gas over a wide range of concentrations from 1 to 100%H2 can be detected via a slope and hysteresis area of the diagram. The sensor response was stable and related almost to an inverse of thermal conductivity of gas. The observed temperature increase during the sweep heating shows a good agreement with a temperature profile calculated from finite element method (FEM). Therefore, the sensor temperature represents the thermal conductivity of gas, although the sweep heating works under non-equilibrium state. From a comparison between platinum, tungsten and cobalt thin-wires, it was confirmed that any metal can be employed for sensing element of this sensor. The proposed sweep heating thin-wire gas sensor is a cost-effective and expected to be suitable for practical use in harsh environment such as automotive applications because of its simple structure and simple working principle. The sweep heating expands diversity on TCD-based gas sensor and contributes to realizing the sustainable development goals (SDGs).

High-speed hydrogen sensor fabricated using a platinum/titanium oxide nanocontact

Titanium dioxide (TiO2) thin films have been extensively studied for use in solid-state hydrogen (H2) gas sensors. In this work, TiOx/platinum (Pt) nanocontacts which constitute a Schottky-diode sensor were developed using shadow evaporation. Large resistance changes and short reaction times were achieved through measurement of the resistance of the contacts. The sensing was quite depended on the thickness of the TiOx layer. The results indicate that the large sensor response over 105 was achieved just neighboring outermost surfaces of TiOx layer. As this sensor can be fabricated at temperatures less than 400 K, it is expected to be applicable to on-tip sensors.

Pivotal role of nucleation layers in the hydrothermally-assisted growth of ZnO and its H2 gas sensing performance

Although hydrogen is a non-poisonous gas that can dissipate quickly once is released, it causes suffocation at high concentrations and is very risky on some occasions if not suitably handled. In this study, an effective approach was suggested for developing and tuning hydrogen gas sensors, where the crucial effect of nucleation layers and chemical stabilizing agents on the morphology of hydrothermally-assisted growth and its gas sensing performance was demonstrated. For this purpose, ZnO seed layers were separately synthesized by different solution-based chemical processes based on the successive ionic layer adsorption and reaction, spin, and dip coating techniques followed by a hydrothermal treatment under the same conditions. X-ray diffraction measurements revealed that all the synthesized samples have a similar pure hexagonal wurtzite structure with a big difference in the degree of textural orientation along the c-axis of ZnO. Optical transmittances, forbidden bandgap energies, and Urbach energies of the produced samples were influenced to a great extent by the coating techniques and the chemical solutions used. Aside from that, the morphology of the synthesized samples and their overall thicknesses together with the available oxygen vacancies detected by X-ray photoelectron spectroscopy changed considerably. The change in structure and morphology have influenced the wettability of the synthesized samples. They have also greatly influenced the gas sensing performance of the sensors in terms of optimal working temperature, sensitivity, and response/recovery periods. The hydrogen gas detection mechanism of the fabricated sensors and the logic behind the change that occurred in gas sensing performance based on morphology are discussed.

Review of Hydrogen Gas Sensors for Future Hydrogen Mobility Infrastructure

Review of Hydrogen Gas Sensors for Future Hydrogen Mobility Infrastructure