Sensitive Hydrogen Gas Sensor Research Articles

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).

Palladium-based trench gate MOSFET for highly sensitive hydrogen gas sensor

This paper presents, Palladium-based Trench Gate MOSFET (TG-MOSFET) for the detection of hydrogen gas. The sensing mechanism occurs with the dissociation of hydrogen molecules into hydrogen atom and then diffuses into the palladium gate. Thereafter, owing to the polarization of the hydrogen atom, the dipole layer is formed at the palladium-oxide (SiO2) interface. From the perspective of a highly sensitive gas sensor, it is observed that the proposed device has very high sensitivity (105 A/A) for different gas pressure applying onto the device. Further, the gate bias dependent sensitivity of the device has been analyzed in terms of change in threshold voltage (ΔVth), surface potential, energy band, and transconductance for the entire range of gas pressure. Furthermore, the device stability is presented and the impact of temperature has also been investigated on the sensing performance of the device. Result reveals that the proposed device is highly sensitive for the detection of hydrogen gas.

Pd-decorated Si nano-horns as sensitive and selective hydrogen gas sensors

The semiconductor industry is based mainly on silicon (Si). Therefore, gas sensors based on Si that have high compatibility with semiconductor technology are among the most promising sensing devices. This study examined the effects of the sensing temperature, selectivity, and detection limits for real applications. This paper reports highly selective hydrogen gas sensors fabricated from Pd-decorated Si nano-horns (NHs). First, Si-NHs were prepared using a simple chemical etching method, which was followed by Pd-decoration using a UV irradiation technique. Electrical and gas sensing measurements showed that the resistance of the gas sensors was affected considerably by the sensing temperature as well as the size of the Pd nanoparticles (NPs). Furthermore, the optimized gas sensor could detect as little as 0.1 ppm H2 gas. The present sensors with exceptional performance toward hydrogen gas have potential use as Si-based hydrogen gas sensors.

Ruthenium Decorated Polypyrrole Nanoparticles for Highly Sensitive Hydrogen Gas Sensors Using Component Ratio and Protonation Control.

Despite being highly flammable at lower concentrations and causing suffocation at higher concentrations, hydrogen gas continues to play an important role in various industrial processes. Therefore, an appropriate monitoring system is crucial for processes that use hydrogen. In this study, we found a nanocomposite comprising of ruthenium nanoclusters decorated on carboxyl polypyrrole nanoparticles (Ru_CPPy) to be successful in detecting hydrogen gas through a simple sonochemistry method. We found that the morphology and density control of the ruthenium component increased the active surface area to the target analyte (hydrogen molecule). Carboxyl polypyrrole (CPPy) in the nanocomposite was protonated to increase the charge transfer rate during gas detection. This material-based sensor electrode was highly sensitive (down to 0.5 ppm) toward hydrogen gas and had a fast response and recovery time under ambient conditions. The sensing ability of the electrode was maintained up to 15 days without structure deformations.

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

Highly sensitive hydrogen gas sensor based on a MoS2-Pt nanoparticle composite

A highly sensitive hydrogen gas sensor composed of an MoS2-Pt nanoparticle thin film as the active layer is introduced. The sensor achieved ultra-fast response and recovery rates of 4 s and 19 s, respectively, for 100 ppm of H2. The MoS2-Pt composite film exhibits a high sensor response (R1/R2) of 10 when exposed to 100 ppm of H2 gas, which outperforms the existing metal sulfide- based sensors. The stability of the device over a period of 70 days and the selectivity of the device is outstanding. A plausible mechanism for the MoS2-Pt based H2 gas sensor is discussed. Furthermore, the sensitivity, response and recovery rates for various concentrations of H2 gas are studied. The sensor response is exceptionally promising. This sensor with metal sulfide-platinum composite active layers can be applied in the sensor field to amplify the sensing performance.

Design and Fabrication Challenges of a Highly Sensitive Thermoelectric-Based Hydrogen Gas Sensor.

This paper presents a highly sensitive thermoelectric sensor for catalytic combustible gas detection. The sensor contains two low-stress (+176 MPa) membranes of a combination of stoichiometric and silicon-rich silicon nitride that makes them chemically and thermally stable. The complete fabrication process with details, especially the challenges and their solutions, is discussed elaborately. In addition, a comprehensive evaluation of design criteria and a comparative analysis of different sensor designs are performed with respect to the homogeneity of the temperature field on the membrane, power consumption, and thermal sensitivity. Evaluating the respective tradeoffs, the best design is selected. The selected sensor has a linear thermal characteristic with a sensitivity of 6.54 mV/K. Additionally, the temperature profile on the membrane is quite homogeneous (20% root mean standard deviation), which is important for the stability of the catalytic layer. Most importantly, the sensor with a ligand (p-Phenylenediamine (PDA))-linked platinum nanoparticles catalyst shows exceptionally high response to hydrogen gas, i.e., 752 mV at 2% concentration.

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.

Enhanced Hydrogen Detection in ppb-Level by Electrospun SnO₂-Loaded ZnO Nanofibers.

High-performance hydrogen sensors are important in many industries to effectively address safety concerns related to the production, delivering, storage and use of H2 gas. Herein, we present a highly sensitive hydrogen gas sensor based on SnO2-loaded ZnO nanofibers (NFs). The xSnO2-loaded (x = 0.05, 0.1 and 0.15) ZnO NFs were fabricated using an electrospinning technique followed by calcination at high temperature. Microscopic analyses demonstrated the formation of NFs with expected morphology and chemical composition. Hydrogen sensing studies were performed at various temperatures and the optimal working temperature was selected as 300 °C. The optimal gas sensor (0.1 SnO2 loaded ZnO NFs) not only showed a high response to 50 ppb hydrogen gas, but also showed an excellent selectivity to hydrogen gas. The excellent performance of the gas sensor to hydrogen gas was mainly related to the formation of SnO2-ZnO heterojunctions and the metallization effect of ZnO.

Enhancement of hydrogen sensing response of ZnO nanowires for the decoration of WO3 nanoparticles

WO3 nanoparticle-decorated ZnO nanowires are synthesized by the hydrothermal and vapor-liquid solid (VLS) methods, respectively. WO3 nanoparticles are decorated on the surface of ZnO nanowires to fabricate the highly sensitive hydrogen gas sensor. This structured sensor presents a sensing response that is 4.3 times higher than its counterpart for 2000 ppm hydrogen gas. The variation in depletion layer width of the ZnO nanowires increases as the WO3 nanoparticles are decorated. This improves the sensing response of the WO3 nanoparticle-decorated ZnO nanowire sensor compared with its counterpart. In this research, a synthetic method of WO3 nanoparticle-decorated ZnO nanowires is described, and its physical and chemical properties are analyzed. Moreover, the sensing responses are measured, and the sensing mechanism is discussed in this literature.

Highly sensitive hydrogen gas sensor based on Al-doped SnO2/Polyaniline composite nanofibers

Highly sensitive hydrogen gas sensor based on Al-doped SnO2/Polyaniline composite nanofibers

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 work function hydrogen gas sensor based on PdNPs/SiO2/Si structure at room temperature

In this study, fabrication of highly sensitive PdNPs/SiO2/Si hydrogen gas sensor using experimental and theoretical methods has been investigated. Using chemical method the PdNPs are synthesized and characterized by X-ray diffraction (XRD). The average size of PdNPs is 11nm. The thickness of the oxide film was 20nm and the surface of oxide film analyzed using Atomic-force microscopy (AFM). The C-V curve for the PdNPs/SiO2/Si hydrogen gas sensor in 1% hydrogen concentration and at the room temperature has been reported. The response time and recovery time for 1% hydrogen concentration at room temperature were 1.2s and 10s respectively. The response (R%) for PdNPs/SiO2/Si MOS capacitor hydrogen sensor was 96%. The PdNPs/SiO2/Si MOS capacitor hydrogen sensor showed very fast response and recovery times compared to SWCNTs/PdNPs, graphene/PdNPs, nanorod/PdNPs and nanowire/PdNPs hydrogen gas sensors.

Palladium decorated silicon carbide nanocauliflowers for hydrogen gas sensing application

Silicon carbide (SiC) nanostructures have attracted significant attention for device applications due to their unique structural, electronic and catalytic properties. Here, the efficiency of three dimensional SiC nano-cauliflowers (NCs) for hydrogen gas sensing application has been investigated. We have deposited a vertically aligned, ordered Pd decorated SiC NCs directly on a silver (Ag) coated porous anodic alumina (AAO) substrate by DC magnetron cosputtering and then it used as a gas sensor without additional processing. The sensor shows remarkably high and selective responses to hydrogen gas with low detection range 2–500ppm at relatively high temperature range (30–500°C). Our results demonstrate the potential application of Pd decorated SiC NCs for fabricating highly sensitive and selective hydrogen gas sensors.

Palladium Gate All Around - Hetero Dielectric -Tunnel FET based highly sensitive Hydrogen Gas Sensor

The paper presents a novel highly sensitive Hetero-Dielectric-Gate All Around Tunneling FET (HD-GAA-TFET) based Hydrogen Gas Sensor, incorporating the advantages of band to band tunneling (BTBT) mechanism. Here, the Palladium supported silicon dioxide is used as a sensing media and sensing relies on the interaction of hydrogen with Palladium-SiO2-Si. The high surface to volume ratio in the case of cylindrical GAA structure enhances the fortuities for surface reactions between H2 gas and Pd, and thus improves the sensitivity and stability of the sensor. Behaviour of the sensor in presence of hydrogen and at elevated temperatures is discussed. The conduction path of the sensor which is dependent on sensors radius has also been varied for the optimized sensitivity and static performance analysis of the sensor where the proposed design exhibits a superior performance in terms of threshold voltage, subthreshold swing, and band to band tunneling rate. Stability of the sensor with respect to temperature affectability has also been studied, and it is found that the device is reasonably stable and highly sensitive over the bearable temperature range. The successful utilization of HD-GAA-TFET in gas sensors may open a new door for the development of novel nanostructure gas sensing devices.

Flexible highly sensitive hydrogen gas sensor based on a TiO2 thin film on polyimide foil

There is currently a high demand for highly-sensitive semiconductor gas sensors operating at low temperature, which would be compatible with semiconductor technology and could be incorporated in one chip with other electronic circuits. Although some suitable sensors were already developed, recent trend of flexible electronics brings yet another challenge for researchers − to prepare such sensors on flexible substrates. In this work, we present a flexible semiconductor gas sensor of hydrogen prepared on 38μm thick Kapton® polyimide foil, based on a TiO2 thin film with platinum interdigital electrodes on top. In dry conditions, the sensor is highly sensitive even at room temperature, with response (R0/RH2) reaching ∼104 for 10000ppm H2 in synthetic air and its capability of sensing H2 concentrations as low as ∼30ppm has been demonstrated. At elevated temperature of 150°C, the response reached more than ∼106 for 10000ppm H2. Humidity negatively affects the sensor performance particularly at room temperature, where at 32% relative humidity the sensor response to 10000ppm H2 decreased to ∼103 and the lowest detected H2 concentration was ∼300ppm H2. Bending the sensor 1000 times over diameter of 10mm did not cause any significant damage of the device or decrease of sensitivity. On the contrary, the response of the sensor at close-to-room temperatures and at low concentrations of H2 increased after the bending.

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.