Selective Hydrogen Gas Sensor Research Articles

Highly selective and extensive range room temperature hydrogen gas sensor based on Pd-Mg alloy thin films

Highly selective and extensive range room temperature hydrogen gas sensor based on Pd-Mg alloy thin films

Highly Sensitive and Selective Hydrogen Gas Sensor with Humidity Tolerance Using Pd-Capped SnO2 Thin Films of Various Thicknesses

Detecting and identifying hydrogen gas leakage before a potential disaster is a critical safety concern. To address this issue, a low-cost and simple-design sensor is required with high response and fast sensing time, capable of detecting hydrogen gas even at low concentrations of 5–500 ppm. This study investigates the use of magnetron-sputtered SnO2 thin films with palladium as a catalytic layer to achieve better sensing output. The developed Pd-caped SnO2 thin film sensors showed increased sensitivity with increasing thickness, up to 246.1 nm at an operating temperature of 250 °C. The sensor with a thickness of 246.1 nm exhibited excellent selectivity for H2 gas, even in humid conditions, and was able to distinguish it from other gases such as CO, NH3, and NO2. The sensor demonstrated high response (99%) with a response/recovery time of 58 s/35 s for (5–500 ppm) hydrogen gas. The sensor showed linear response to H2 gas concentration variation (5–500 ppm) at 250 °C. The sensor was found to be mechanically stable even after 60 days in a high-humidity environment. The LOD of sensor was 151.6 ppb, making it a suitable candidate for applied sensing applications. The Pd-caped SnO2 thin film sensor with thickness of ~245 nm could potentially improve the safety of hydrogen gas handling.

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.

An Analysis of a Highly Sensitive and Selective Hydrogen Gas Sensor Based on a 3D Cu-Doped SnO2 Sensing Material by Efficient Electronic Sensor Interface.

In this research, a highly sensitive and selective hydrogen gas sensor was developed based on Cu-doped SnO2. Sensing characteristics were compared based on SnO2 doped with different concentrations of Cu, and the highest sensitivity and fastest response time were shown when 3% Cu was contained. A 3D structure was formed using a polystyrene to increase the surface-to-volume ratio, which allows more oxygen molecules to bond with the surface of the SnO2 sensing material. Extremely increased sensitivity was observed as compared to the planar structure. A temperature sensor and micro-heater were integrated into the sensor, and the surface temperature was maintained constant regardless of external influences. In addition, an electronic sensor interface was developed for the efficient analysis of real-time data. The developed sensor was wire-bonded to the flexible printed circuit board (FPCB) cable and connected with the sensor interface. Sensitivity and linearity measured based on the developed sensor and interface system were analyzed as 0.286%/ppm and 0.98, respectively, which were almost similar to the results observed by a digital multimeter (DMM). This indicates that our developed sensor system can be a very promising candidate for real-time measurement and can be applied in various fields. The enhanced sensitivity of 3% doped SnO2 toward hydrogen is attributed to the huge number of oxygen vacancies in the doped sample.

Sputter-Grown Pd-Capped CuO Thin Films for a Highly Sensitive and Selective Hydrogen Gas Sensor

In the present work, hydrogen gas sensing properties of palladium-capped copper oxide (Pd/CuO) thin films have been investigated. The Pd/CuO thin films were deposited on glass substrate for different deposition times (10–30 min) using direct current magnetron sputtering. The Pd/CuO thin films were characterized by x-ray diffraction, field emission scanning electron microscopy, atomic force microscopy and x-ray photoelectron spectroscopy for their structural, morphological and compositional properties, respectively. The Pd/CuO thin film sensor deposited for 10 min presents a remarkable sensing performance with fast response/recovery time of 10 s/50 s for hydrogen gas at a concentration of (1000 ppm) and optimum operating temperature of 300°C. The sensor is observed to be highly selective towards hydrogen (H2) gas compared to the other gases such as carbon monoxide (CO) and ammonia (NH3). The sensor is stable under high humidity conditions (60% RH). The studied Pd/CuO thin film sensor can be used to design a simple and low-cost sensor to detect low concentrations of H2 gas for use in hydrogen-driven industries.

Synthesis of Pd nanoparticle-decorated SnO2 nanowires and determination of the optimum quantity of Pd nanoparticles for highly sensitive and selective hydrogen gas sensor

Pd nanoparticle-decorated SnO2 nanowires were synthesized to fabricate a highly selective and sensitive hydrogen gas sensor. The SnO2 nanowires were synthesized via a vapor–liquid–solid process, and Pd nanoparticles were decorated by a UV irradiation process using 1 mM PdCl2 solution to improve the hydrogen sensing properties of SnO2 nanowires. To generate Pd nanoparticles on the surface of SnO2 nanowires, 254 nm UV light was irradiated on SnO2 nanowires that were immersed in PdCl2 aqua solution, and the irradiation time was manipulated to control the number of Pd nanoparticles. The Pd nanoparticle-decorated SnO2 nanowires showed different hydrogen sensing responses followed by quantity of Pd nanoparticles, and the response of the optimum number of Pd nanoparticle-decorated SnO2 nanowires was 12.7 times that of bare-SnO2 nanowires when exposed 100 ppm of hydrogen gas. Furthermore, the selectivity of this nanowire-based sensor also improved as the Pd nanoparticles were decorated. The SnO2 nanowires exhibited similar sensing responses to several gases, but the hydrogen sensing response increased significantly after Pd nanoparticle decoration. In this case, the sensing response to hydrogen was 5 times higher than that of ethanol gas that showed the second-best response to the sensor. This improvement resulted from the catalytic effect of Pd nanoparticles and the formation of Schottky junctions between Pd nanoparticles and SnO2 nanowires. The mechanisms of the improved hydrogen sensing response of Pd nanoparticle-decorated SnO2 nanowires were discussed, and the optimum quantity of Pd nanoparticles required to obtain the best hydrogen sensing properties was discussed in this research.

Characterization of a highly sensitive and selective hydrogen gas sensor employing Pt nanoparticle network catalysts based on different bifunctional ligands

A catalytic hydrogen gas sensor of superior sensitivity, selectivity, resolution and dynamic response was developed with catalysts composed of ligand-stabilized Pt nanoparticles. We have characterized different catalysts utilizing the bi-functional ligands trans-1,4-diaminocyclohexane (DACH), 1,5-diaminonaphthalene (DAN), 4,4´´-diamino-p-terphenyl (DATER), benzidine (BEN) and p-phenylene diamine (PDA) for hydrogen gas sensing. A comprehensive evaluation by comparison, with respect to both, structural aspects (TEM and SEM) and gas sensing performance of the 5 types of ligand-linked Pt nanoparticles and non-stabilized Pt nanoparticles was conducted to select the optimized catalysts. From this investigation, DATER-linked Pt nanoparticles appear immensely promising: the sensor is selective to hydrogen and shows extremely high sensitivity, around 400 mV/1% vol., but exhibits no crosssensitivity to methane and ethane. Likewise, sensors with DATER- and DAN-linked Pt nanoparticles can detect down to 0.001 % (10 ppm) alongside 650 ms average response time (t90).

Pt Nanoparticle Sensitized PdNi Nanofibers As Highly Sensitive and Selective Hydrogen Gas Sensor

Detection of different gases in power transformer oil is essential to accurately examine and understand different problems and faults in the transformer system. Especially, during situations like corona discharge and arcing, evolution of hydrogen gas can be hazardous due to its highly flammable and explosive nature. Therefore, development of high-performance gas sensors targeted for hydrogen gas over a wide range of concentrations is very important.We suggest a facile and effective fabrication method of hydrogen sensing composite material based on palladium and nickel alloy with nanofiber structures originated from electrospinning. PdNi alloy, with further decoration with platinum nanoparticles as catalysts via apo-ferritin templating, shows greatly enhanced sensitivity and response time. Conventionally, Palladium is widely used as hydrogen sensors due to its well-known phase transition to PdHx, α-PdHx at hydrogen concentration below 1%, and β-PdHx at hydrogen concentration above 2%. However, huge volume expansion associated from this transformation limits its lifetime and reduces its long-term performance. In this work, nickel alloying effectively decreases the lattice parameters of the alloy, while increasing the stability during repetitive exposure to high concentration to hydrogen gas. Furthermore, formation of grain boundaries to compensate the lattice contraction induced by nickel alloying, high surface area from its nanofiber structure and gas dissociation and activation properties of platinum nanoparticles improves the sensor’s sensitivity toward hydrogen gas [1]. Nickel in the lattice also acts as pinning points to effectively suppress the grain growth of the alloy during high temperature annealing and reduction processes, which further improves its sensitivity and response time. This facile fabrication and decoration methods allow us to produce a highly sensitive and rapidly responding hydrogen gas sensor with enhanced long-term stability compared to the conventional Pd based hydrogen gas sensors. Reference [1] D. H. Kim, ACS Nano 13, 6071–6082 (2011); doi:10.1021/acsnano.9b02481

Fe overlayered hybrid TiO2/ITO nanocomposite sensor for enhanced hydrogen sensing at room temperature by novel two step process

We report on the fabrication of highly sensitive and selective hydrogen gas sensor based on Fe metal overlayered TiO2/ITO heterostructure synthesized by novel two-step deposition using spray pyrolysis and electron beam evaporation. XRD analysis revealed that the films were polycrystalline with the tetragonal crystal structure of anatase TiO2. Overlayer of Fe in TiO2 film resulted in the incorporation of Fe³+ ions into TiO2/ITO matrix which leads to a red shift in the optical response, as well as a reduction in the bandgap energy. The Raman spectroscopy also confirmed the formation of an anatase phase structure in both pure and nanocomposited Fe:TiO2/ITO films. FE-SEM images of TiO2/ITO and Fe/TiO2/ITO films revealed interconnected web like spherical structure favorable for sensing. AFM images revealed a high rms roughness of 6.49 nm for the hybrid film fabricated with the Fe deposition time of 10 min. The gas sensing behavior of Fe:TiO2/ITO nanocomposite exhibited a high sensitivity on exposure to H2 gas in the low concentration range from 100 ppm to 400 ppm. The hybrid sensor fabricated with the Fe deposition time of 10 min. revealed a fast response time of 40 S even at room temperature.

Fabrication of porous silicon filled Pd/SiC nanocauliflower thin films for high performance H2 gas sensor

In this work, we have fabricated the Pd decorated silicon carbide (SiC) nanocauliflowers (NCs) thin films on electrochemically etched porous silicon (PS) substrate by DC magnetron co-sputtering technique. The gas sensing performance of Pd/SiC NCs to hydrogen gas under low (5–500 ppm) detection limit at high operating temperature regime (40–500 °C) were studied in detail without additional processing. The nanocauliflowers sensor demonstrates the high sensing response (Ra/Rg ̴ 14.48), fast response/recovery time (10s/18s) with excellent stability (24 cycles) towards 100 ppm H2 at high temperature of 380 °C. The underlying sensing mechanism behind the notable performance of the proposed sensing action towards H2 was also discussed in detail. Therefore, the investigated Pd/SiC NCs can be used as highly sensitive and selective hydrogen gas sensor at high working temperatures in harsh environment.

Hydrogen gas sensing properties of platinum decorated silicon carbide (Pt/SiC) Nanoballs

In the present study, platinum decorated silicon carbide (Pt/SiC) nanoballs (NBs) were directly grown on Ag coated porous Si substrates via DC/RF magnetron sputtering. Porous Si substrates were prepared by the metal-assisted chemical etching process at room temperature. The structural and morphological properties of as-grown SiC nanoballs (NBs) were studied using various techniques such as X-ray diffraction (XRD), Raman spectroscopy and field scanning electron microscopy (FESEM) respectively. Hydrogen gas sensing properties along with the sensing mechanism of Pt/SiC nanoball-based sensor within low detection limit (5–1000 ppm) at the high operating temperature range (30–480 °C) were investigated in detail. The sensor exhibits high sensing response (44.48%) with very fast response time (15 s) toward 100 ppm hydrogen gas at 330 °C. These above results suggest the feasibility of Pt decorated SiC nanoballs for highly sensitive and selective hydrogen gas sensor at the high operating temperature and harsh environment conditions.

Highly Sensitive and Selective Hydrogen Gas Sensor Using the Mesoporous SnO₂ Modified Layers.

It is important to improve the sensitivities and selectivities of metal oxide semiconductor (MOS) gas sensors when they are used to monitor the state of hydrogen in aerospace industry and electronic field. In this paper, the ordered mesoporous SnO2 (m-SnO2) powders were prepared by sol-gel method, and the morphology and structure were characterized by X-ray diffraction analysis (XRD), transmission electron microscope (TEM) and Brunauer–Emmett–Teller (BET). The gas sensors were fabricated using m-SnO2 as the modified layers on the surface of commercial SnO2 (c-SnO2) by screen printing technology, and tested for gas sensing towards ethanol, benzene and hydrogen with operating temperatures ranging from 200 °C to 400 °C. Higher sensitivity was achieved by using the modified m-SnO2 layers on the c-SnO2 gas sensor, and it was found that the S(c/m2) sensor exhibited the highest response (Ra/Rg = 22.2) to 1000 ppm hydrogen at 400 °C. In this paper, the mechanism of the sensitivity and selectivity improvement of the gas sensors is also discussed.

Highly sensitive and selective hydrogen gas sensor using sputtered grown Pd decorated MnO2 nanowalls

Two-dimensional (2D) materials have attracted significant attention for device applications due to their unique structural, electronic and catalytic properties. Here, we have deposited a vertically aligned, highly ordered Pd decorated MnO2 nanowalls directly on a porous anodic alumina (AAO) by reactive sputtering and then it used as a gas sensor without additional processing. The nanowalls sensor shows remarkably high and selective responses to hydrogen gas with low detection range 10–10000ppm. Our results demonstrate the potential application of Pd decorated MnO2 nanowalls for fabricating highly sensitive and selective gas sensors.

Aerosol-Assisted CVD-Grown PdO Nanoparticle-Decorated Tungsten Oxide Nanoneedles Extremely Sensitive and Selective to Hydrogen.

We report for the first time the successful synthesis of palladium (Pd) nanoparticle (NP)-decorated tungsten trioxide (WO3) nanoneedles (NNs) via a two-step aerosol-assisted chemical vapor deposition approach. Morphological, structural, and elemental composition analysis revealed that a Pd(acac)2 precursor was very suitable to decorate WO3 NNs with uniform and well-dispersed PdO NPs. Gas-sensing results revealed that decoration with PdO NPs led to an ultrasensitive and selective hydrogen (H2) gas sensor (sensor response peaks at 1670 at 500 ppm of H2) with low operating temperature (150 °C). The response of decorated NNs is 755 times higher than that of bare WO3 NNs. Additionally, at a temperature near that of the ambient temperature (50 °C), the response of this sensor toward the same concentration of H2 was 23, which is higher than that of some promising sensors reported in the literature. Finally, humidity measurements showed that PdO/WO3 sensors displayed low-cross-sensitivity toward water vapor, compared to bare WO3 sensors. The addition of PdO NPs helps to minimize the effect of ambient humidity on the sensor response.

Selective hydrogen gas sensor using CuFe2O4 nanoparticle based thin film

Hydrogen gas sensors based on CuFe2O4 nanoparticle thin films are presented in this work. Each gas sensor was prepared by depositing CuFe2O4 thin film on a glass substrate by dc sputtering inside a high vacuum chamber. Argon inert gas was used to sputter the material from a composite sputtering target. Interdigitated metal electrodes were deposited on top of the thin films by thermal evaporation and shadow masking. The produced sensors were tested against hydrogen, hydrogen sulfide, and ethylene gases where they were found to be selective for hydrogen. The sensitivity of the produced sensors was maximum for hydrogen gas at 50°C. In addition, the produced sensors exhibit linear response signal for hydrogen gas with concentrations up to 5%. Those sensors have potential to be used for industrial applications because of their low power requirement, functionality at low temperatures, and low production cost.

Sol-Gel Derived ZnO: Nb2O5 Nanocomposite as Selective Hydrogen (H2) Gas Sensor

The present study investigates the incentive studies on phase transformations of ZnO: Nb2O5 nano composite, synthesized by sol gel protocol followed by impregnation process for sensing hydrogen gas. Detailed analyses of the synthesized nanomaterials were carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Particle size analysis. The material was subjected to different annealing temperatures ranging from 400°C to 800°C. The XRD result revealed the formation of single phase ZnNb2O6 at 700°C and above with average particle size of ∼ 67nm. ZnO: Nb2O5 based sensor has shown enhanced gas sensing properties towards 1000ppm H2 gas.

Fabrication of highly sensitive and selective H2 gas sensor based on SnO2 thin film sensitized with microsized Pd islands

Ultrasensitive and selective hydrogen gas sensor is vital component in safe use of hydrogen that requires a detection and alarm of leakage. Herein, we fabricated a H2 sensing devices by adopting a simple design of planar-type structure sensor in which the heater, electrode, and sensing layer were patterned on the front side of a silicon wafer. The SnO2 thin film-based sensors that were sensitized with microsized Pd islands were fabricated at a wafer-scale by using a sputtering system combined with micro-electronic techniques. The thicknesses of SnO2 thin film and microsized Pd islands were optimized to maximize the sensing performance of the devices. The optimized sensor could be used for monitoring hydrogen gas at low concentrations of 25–250ppm, with a linear dependence to H2 concentration and a fast response and recovery time. The sensor also showed excellent selectivity for monitoring H2 among other gases, such as CO, NH3, and LPG, and satisfactory characteristics for ensuring safety in handling hydrogen. The hydrogen sensing characteristics of the sensors sensitized with Pt and Au islands were also studied to clarify the sensing mechanisms.

Trace level detection of hydrogen gas using birnessite-type manganese oxide

A new, highly sensitive and selective hydrogen gas (H2) sensor based on birnessite-type manganese oxide (δ-MnO2) nanoflakes was prepared. The δ-MnO2 nanoflakes sensor selectively detected H2 with detection limits in air of 150ppb at 200°C and 7.5ppm at room temperature. In addition, the sensor also exhibited a considerable response to H2 in an N2 atmosphere. The sensor rapidly responded to trace levels of H2 gas and displayed reversible recovery, while the detected H2 concentrations could be accurately calculated using a modified Langmuir isotherm adsorption equation. The influence of the temperature and humidity on the sensing performance of the sensor was also investigated. The mechanism of the sensor is based on the oxidation of H2O and H2 accompanied by the formation and oxidation of MnOOH. It is believed that the low detection limit, high selectivity and fast reversible response of the δ-MnO2 nanoflake sensor are important benefits that make this sensor a promising candidate for H2 leak detection.

A highly sensitive and selective hydrogen gas sensor from thick oriented films of MoS2

A new process is developed to fabricate a highly sensitive and selective hydrogen sensor by depositing a partially crystalline and highly oriented film of MoS2 from its single layer suspension on an alumina substrate. When these films are promoted with some catalysts selected from Pt-group metals (Pt, Pd, Ru or any combination of these metals) they exhibit a high sensitivity and selectivity to hydrogen gas. Unlike other metal oxide sensors which are sensitive to many reducing and oxidizing gases and operate at a temperature of 350 °C or higher; this sensor is highly selective to hydrogen gas and its operating temperature is from 25 to 150°C. The lower operating temperature enhances safety when dealing with hydrogen gas. The sensor response to hydrogen at 120 °C is linear in concentration from 30 to 104 ppm with a 10 to 30 second response time and a 45 to 90 second recovery time. Above 104 ppm the sensor is still linear but the slope of conductance versus hydrogen concentration changes.

A highly sensitive and selective hydrogen gas sensor from thick oriented films of MoS 2

A highly sensitive and selective hydrogen gas sensor from thick oriented films of MoS 2