Sensitive Hydrogen Sensor Research Articles

A CMOS-compatible and cost-effective room temperature sensitive hydrogen sensor

Hydrogen has a promising future as a renewable energy for fossil fuels. Nevertheless, hydrogen leakage will induce a great risk of explosion. It becomes a crucial work to implement fast and safe hydrogen leakage detection. In the paper, we develop an optical Schottky junction hydrogen sensing chip operating at room temperature (298 K). The sensor has a response time of 4 s in a 2 % H2 with Air atmosphere and a detection limit can be 10 ppm by detecting the inhibition of photocurrent induced by hydrogen. When the temperature rises, the sensor response time can reduce to 1 s at 340 K. Additionally, the sensors are CMOS-compatible and cost-effective without a heat source or voltage-biased state. The properties of the sensor allow for rapid and large-scale use of on-site monitoring to reduce the risk of hydrogen leakage.

Advancing Hydrogen Sensing for Sustainable Aviation: A Metal Hydride Coated TFBG Optical Fibre Hydrogen Sensor

The aviation industry is undergoing a significant shift toward sustainability, with hydrogen emerging as a promising green fuel to reduce carbon emissions due to its high gravimetric energy density and clean combustion exhaust compared to traditional aviation fuels. However, realizing hydrogen's aviation potential requires advanced sensors to ensure safety and efficiency in challenging environments, particularly for monitoring hydrogen near high-temperature engines and cryogenic storage tanks. Fibre optic sensors offer an exceptional advantage in these demanding conditions due to their capacity to operate in harsh environments, their small size, immunity to electromagnetic interference, spark-free operation, and remote sensing capabilities. Metal hydrides are prominent sensing materials studied for hydrogen sensing, especially palladium (Pd). Nonetheless, existing literature pertaining to Pd-coated fiber optic sensors for hydrogen detection has brought to light concerns regarding response hysteresis, stability, and linearity of Pd hydrogen sensors, calling for innovative solutions. In response to these challenges, our research introduces an innovative fibre optic hydrogen sensor, introducing tantalum (Ta) based metal hydrides as the sensing material. The sensor's construction involved the deposition of a nanometer-thick Ta thin film onto the surface of a tilted fibre Bragg grating (TFBG) using a magnetron sputtering technique. The sensing mechanism relies on the modulation of optical constants of the Ta thin film in response to even minute hydrogen concentrations, culminating in spectral changes in the transmission spectrum of the TFBG. In this proof of concept work, changes in both amplitude and the centre wavelength of cladding resonances of the TFBG transmission spectrum were observed in the hydrogen concentration range from 0.01% to 4% at room temperature. These initial findings underscore the substantial potential of our approach in developing highly sensitive and robust fibre-optic hydrogen sensors tailored specifically for hydrogen-powered aviation.

Sensitive and Repeatable Optical Fiber Hydrogen Sensors Using Plasma-induced Oxygen Vacancies Magnetron Sputtering Coating Technique

Sensitive and Repeatable Optical Fiber Hydrogen Sensors Using Plasma-induced Oxygen Vacancies Magnetron Sputtering Coating Technique

P-Toluenesulfonic acid doped vanadium pentoxide/polypyrrole film for highly sensitive hydrogen sensor

p-Toluenesulfonic acid doped vanadium pentoxide/polypyrrole film for highly sensitive hydrogen sensor

Atomic layer deposited SnO2/ZnO composite thin film sensors with enhanced hydrogen sensing performance

Hydrogen gas (H2) has long been regarded as a clean and renewable energy carrier alternative to the fossil fuel, therefore the development of highly sensitive and reliable hydrogen sensor is imperative for the large-scale implementation of green energy hydrogen. In this work, SnO2, ZnO thin film and SnO2/ZnO composite thin film H2 sensors were fabricated on SiO2/Si substrates by atomic layer deposition (ALD). The effect of ALD cycles and heat treatment temperatures on the sensing properties of the thin film sensors was investigated deeply. It is found that the 100-cycle SnO2/150-cycle ZnO composite film shows the best H2-sensing performance such as large response of 93 to 30 ppm H2 at 200 ℃, fast response/recovery time of 50 s/29 s, and low detection limit of 250 ppb. Moreover, the response of SnO2/ZnO composite film sensor is 10 times and 2 times higher than that of the pure ZnO and SnO2 thin film ones at working temperature of 200℃, respectively. A possible mechanism for performance improvement of the SnO2/ZnO composite film H2 sensor is proposed, attributed to the synergistic effect of the SnO2-ZnO heterojunction and the oxygen vacancies in the SnO2 film. ALD may be a feasible strategy to construct Si-based highly sensitive hydrogen sensors for micro-electromechanical system application.

Highly sensitive and wrappable room temperature wireless gasochromic and chemiresistive dual-response H2 sensors using spray coating

Developing highly reliable, sensitive and room temperature operation hydrogen (H2) sensors is essential to adapt successfully to the H2 economy. Despite the development of various H2 sensors, detecting leaks and pinpointing their precise location remains challenging because of the highly diffusive nature of H2 and environmental factors such as the wind direction. This study reports the development of room temperature, wireless, dual-signal, wrappable, chemiresistive, and eye-readable gasochromic H2 sensors using solution-based and low temperature annealed SnO2/WO3 films on polyimide substrate. These sensors can be wrapped around any point source, such as flanges, rendering the early detection and pinpointing of H2 leaks. An optimized spray-coated gasochromic WO3 film achieves a color change value (ΔE) of 11 with a 6 s response time at 4% H2 and low eye detectable limit of 0.2%. Simultaneously, because a patterned spray-coated gasochromic layer does not interfere with the active area of a SnO2-based chemiresistive sensor, the resistance value of the sensor changes by more than 11,000 times at 1% H2 with a wide concentration range from 0.005% to 2% of H2 at room temperature. Such a sensor can be easily applied to various nonplanar surfaces, while the Bluetooth system integration enables wireless monitoring via smartphones. Our study provides a simple strategy to develop wrappable dual-signal wireless sensors for reliable detection and monitoring of H2 leaks at room temperature.

Highly sensitive and wide range hydrogen sensor based on thin films of AgInO2 by pulsed laser deposition

There has been mounting effort in the research on delafossite compounds due to their fascinating layered structure, chemical or optoelectronic properties for a wide range of industrial applications. However, thin film synthesis is known to be extremely challenging owing to their low symmetry rhombohedral structures, which limit the selection of substrates for thin film growth. In this study, AgInO2 is deposited on glass substrate by pulsed laser deposition at 0.7 mbar in-situ oxygen pressure, far higher than the usual range of 0.05–0.17 mbar for growth of multicomponent oxides for the first time. Stabilization of Ag+ ion as Ag2O is the crucial step which requires 0.7 mbar oxygen pressure for Ag particles free AgInO2. The deposited thin films show n-type behaviour with a carrier concentration of 1.1 × 1016 cm−3 at room temperature. Gas sensing studies revealed that thin films were highly selective to hydrogen with a significant reduction in response and recovery times when compared to that of thick films with long-term baseline stability. This single step process with low temperature growth conditions is compatible with direct deposition onto cost-effective and flexible substrates for widespread applications.

Hydrogenase-based electrode for hydrogen sensing in a fermentation bioreactor

The hydrogen-based economy will require not only sustainable hydrogen production but also sensitive and cheap hydrogen sensors. Commercially available H2 sensors are limited by either use of noble metals or elevated temperatures. In nature, hydrogenase enzymes present high affinity and selectivity for hydrogen, while being able to operate in mild conditions. This study aims at evaluating the performance of an electrochemical sensor based on carbon nanomaterials with immobilised hydrogenase from the hyperthermophilic bacterium Aquifex aeolicus for H2 detection. The effect of various parameters, including the surface chemistry, dispersion degree and amount of deposited carbon nanotubes, enzyme concentration, temperature and pH on the H2 oxidation are investigated. Although the highest catalytic response is obtained at a temperature around 60 °C, a noticeable current can be obtained at room temperature with a low amount of protein less than 1 μM. An original pulse-strategy to ensure H2 diffusion to the bioelectrode allows to reach H2 sensitivity of 4 μA cm−2 per % H2 and a linear range between 1 and 20%. Sustainable hydrogen was then produced through dark fermentation performed by a synthetic bacterial consortium in an up-flow anaerobic packed-bed bioreactor. Thanks to the outstanding properties of the A. aeolicus hydrogenase, the biosensor was demonstrated to be quite insensitive to CO2 and H2S produced as the main co-products of the bioreactor. Finally, the bioelectrode was used for the in situ measurement of H2 produced in the bioreactor in steady-state.

Ultrasensitive and Wide‐Range Flexible Hydrogen Sensor Based on Pd Nanoparticles Decorated Ultrathin SnO2 Film

AbstractHighly sensitive and reliable hydrogen detection is prerequisite for the large‐scale implementation of green energy hydrogen. It remains a tough challenge to get a highly selective H2 sensor to low concentration H2 gas with low working temperature. In this work, high performance flexible hydrogen sensor using ultrathin SnO2 film decorated by Pd nanoparticles (NPs) on polyimide (PI) was developed based on versatile atomic layer deposition (ALD) and cluster beam deposition (CBD). The influence of Pd NPs loading amount and operating temperature on the performance of hydrogen sensors was studied. The sensors obtain an extremely high response over 20000 to 30 ppm H2 at the relatively low operating temperature of 75–125 °C. The Pd NPs@SnO2/PI sensor achieves a wide detection range of 0.1‐5000 ppm with the limit of detection (LOD) of 100 ppb at 125 °C. A low LOD of 250 ppb can still be achieved at room temperature. The sensors also exhibit outstanding sensing selectivity for hydrogen over interfering gases and excellent mechanical resistance after 2000 bending cycles. The mechanism for improved sensing performance of ALD ultrathin film with CBD‐derived noble metal NPs decoration may be a feasible strategy for the construction of highly sensitive, selective, and flexible hydrogen sensors.

A Sensor With Coating Pt/WO Powder With an Erbium-Doped Fiber Amplifier to Detect the Hydrogen Concentration

A highly sensitive hydrogen sensor (HS) coated with Pt/WO3 powder with an erbium-doped fiber amplifier (EDFA) is proposed and experimentally demonstrated. The sensing head is constructed by splicing a short Section of tapered small-diameter coreless fiber (TSDCF diameter of 62.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> and tapered to 14.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> ) between two single-mode fibers (SMFs). The Pt/WO3 powder adheres to the surface of polydimethylsiloxane (PDMS) film coated on the TSDCF structure, which is sensitive to hydrogen. An EDFA is introduced into the sensor system to improve the quality factor ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> -factor) of the output spectrum and thus improve the sensor’s resolution. As the hydrogen concentration varies from 0% to 1.44%, the measured maximum light intensity variation and the sensor’s sensitivity are −32.41 dB and −21.25 dB/%, respectively. The sensor demonstrates good stability with the light intensity fluctuation of < 1.26 dB over a 30-min duration.

Enhanced Pd/a-WO3 /VO2 Hydrogen Gas Sensor Based on VO2 Phase Transition Layer.

The utilization of clean hydrogen energy is becoming more feasible for the sustainable development of this society. Considering the safety issues in the hydrogen production, storage, and utilization, a sensitive hydrogen sensor for reliable detection is essential and highly important. Though various gas sensor devices are developed based on tin oxide, tungsten trioxide, or other oxides, the relatively high working temperature, unsatisfactory response time, and detection limitation still affect the extensive applications. In the current study, an amorphous tungsten trioxide (a-WO3 ) layer is deposited on a phase-change vanadium dioxide film to fabricate a phase transition controlled Pd/a-WO3 /VO2 hydrogen sensor for hydrogen detection. Results show that both the response time and sensitivity of the hydrogen sensor are improved greatly if increasing the working temperature over the transition temperature of VO2 . Theoretical calculations also reveal that the charge transfer at VO2 /a-WO3 interface becomes more pronounced once the VO2 layer transforms to the metal state, which will affect the migration barrier of H atoms in a-WO3 layer and thus improve the sensor performance. The current study not only realizes a hydrogen sensor with ultrahigh performance based on VO2 layer, but also provides some clues for designing other gas sensors with phase-change material.

Reflective-Type High Sensitivity Optical Fiber Hydrogen Sensor Based On Enlarged Taper Cascaded With Tilted Fiber Grating

Highly sensitive reflective-type fiber hydrogen sensor based on an enlarged taper cascaded with a tilted fiber grating (TFBG) was proposed. Hydrogen-sensitive Au-Pd nanofilm was coated on the TFBG surface by magnetron sputtering means. By cascading an enlarged taper upstream to the TFBG, cladding modes and Ghost mode of the TFBG could be coupled into the core to form a reflective-type TFBG-based hydrogen sensor. As the hydrogen was absorbed by the Au-Pd nanofilm, the effective refractive index of the cladding of the TFBG will change accordingly, so as to the reflective spectra of the TFBG. The hydrogen concentration was obtained through the intensity changing of the ghost mode in the reflective spectra of TFBG. The proposed sensor showed a high sensitivity of 4.83 dB/% with a calculated LOD of 0.07% for the hydrogen concentration range from 0% to 0.7% at room temperature with the rapid response time of 26 s and recovery time of 40 s, respectively.

Palladium Based Microwave Resonant Hydrogen Sensor

AbstractAs the surge for renewable and clean energy resources increases, new challenges emerge. One of the challenges related to the use of hydrogen as a clean energy source is safety. In this study, a microwave hydrogen sensor has been presented for detection of hydrogen leakage. An analytical model is developed and the performance of the sensor is investigated using numerical analysis tools. It has been shown that with optimal geometrical parameters of the sensor structure, a wide range of sensitivity levels depending on a wide range of Q‐factor can be achieved. Utilizing a palladium disk with a radius of 750 μm can detect hydrogen with a sensitivity as high as 30 MHz per % hydrogen when μm. Average error between analytical model and numerical results is 0.23%. With reference to this work, it is believed that more compact and sensitive microwave hydrogen sensors will be produced for future uses.

Highly Sensitive Hydrogen Sensor Based on an Optical Driven Nanofilm Resonator.

Nanofilm resonators combine ultracompact and highly mechanically sensitive properties, making them intriguing devices for sensing applications. For trace hydrogen detection, we demonstrate an optomechanical nanofilm resonator by employing a Pd- and Au-decorated graphene onto a fiber end facet. The Pd layer is a sensitive layer for selective absorption of hydrogen. Hydrogen sensing is achieved by all-optical measuring of the resonant frequencies shift of the optomechanical nanofilm resonator induced by hydrogen-related mechanical stress change. Using the approach, we realize highly sensitive hydrogen sensing at room temperature with a low detection limit, challenging the state-of-the-art. When the measured hydrogen concentration increases from 0 to 1000 ppm (v/v), the mechanical resonance frequencies of the sensor at 511.7 kHz, 1253.4 kHz, and 2231.7 kHz blue-shift by 100.4 kHz, 257.5 kHz, and 400.6 kHz, respectively. The response and recovery time are 120.3 and 91.3 s at a 1000 ppm hydrogen concentration. Such a sensor exhibits a low detection limit of 741 ppb and good repeatability in the measurement process, which makes the practical application of the sensor possible.

Two-Dimensional Dy2O3-Pd-PDA/rGO Heterojunction Nanocomposite: Synergistic Effects of Hybridisation, UV Illumination and Relative Humidity on Hydrogen Gas Sensing

A two-dimensional (2D) Dy2O3-Pd-PDA/rGO heterojunction nanocomposite has been synthesised and tested for hydrogen (H2) gas sensing under various functioning conditions, including different H2 concentrations (50 ppm up to 6000 ppm), relative humidity (up to 25 %RH) and working temperature (up to 200 °C). The material characterisation of Dy2O3-Pd-PDA/rGO nanocomposite performed using various techniques confirms uniform distribution of Pd NPs and 2D Dy2O3 nanostructures on multi-layered porous structure of PDA/rGO nanosheets (NSs) while forming a nanocomposite. Moreover, fundamental hydrogen sensing mechanisms, including the effect of UV illumination and relative humidity (%RH), are investigated. It is observed that the sensing performance is improved as the operating temperature increases from room temperature (RT = 30 °C) to the optimum temperature of 150 °C. The humidity effect investigation revealed a drastic enhancement in sensing parameters as the %RH increased up to 20%. The highest response was found to be 145.2% towards 5000 ppm H2 at 150 °C and 20 %RH under UV illumination (365 nm). This work offers a highly sensitive and selective hydrogen sensor based on a novel 2D nanocomposite using an environmentally friendly and energy-saving synthesis approach, enabling us to detect hydrogen molecules experimentally down to 50 ppm.

Fabrication of ZnO Nanobrushes by H2-C2H2 Plasma Etching for H2 Sensing Applications.

Zinc oxide has widespread use in diverse applications due to its distinct properties. Many of these applications benefit from controlling the morphology on the nanoscale, where for example gas sensing is strongly enhanced for high surface-to-volume ratios. In this work the formation of novel ZnO nanobrushes by plasma etching treatment as a new approach is presented. The morphology and structure of the ZnO nanobrushes are studied in detail by transmission and scanning electron microscopy. It is revealed that ZnO nanobrush structures are fabricated by self-patterned preferential etching of ZnO microtetrapods in a hydrogen-acetylene plasma. The etching process was found to be most effective at 1% C2H2 admixture. Nanowire arrays are formed enabled by sidewall passivation due to a-C:H deposition. The nanobrush structures are further stabilized by simultaneous deposition of a SiOx layer from the opposite direction. Highly sensitive (gas response S = 148), selective, and fast (response time 15s, recovery time 6 s) hydrogen sensors are fabricated from single nanobrushes. Single nanobrush sensors show enhanced sensing performance in increased gas response S of at least 10 times and improved response as well as recovery times when compared to nonporous single ZnO nanorod sensors due to the small diameters (≈50 nm) of the formed nanowires as well as the strongly enhanced surface-to-volume ratio of the nanobrushes by a factor of more than 10.

Highly sensitive ozone and hydrogen sensors based on perovskite microcrystals directly grown on electrodes

Highly-sensitive and stable ozone and hydrogen sensing elements were fabricated based on well-crystalline rounded cube-shaped CsPbBr3 microcrystals, synthesized by a facile solution process performed under ambient conditions. It is shown that such elements demonstrate enhanced room temperature gas sensing ability compared to the previously reported metal halide and oxide-based ones. Electrical measurements performed on these sensing components revealed high sensitivity to ultra-low ozone and hydrogen concentrations, namely 4 ppb and 1 ppm respectively, as well as a remarkable repeatability, even after a few months of storage in ambient conditions. Both ozone and hydrogen sensors were self-activated, as they did not require the use of UV or heating external stimuli to operate, and exhibited fast detection and short restoration times. All such attractive properties along with the simple fabrication process could provide an easy, efficient and low-cost technology for the realization of future gas sensing devices.

Sub-second and ppm-level optical sensing of hydrogen using templated control of nano-hydride geometry and composition

The use of hydrogen as a clean and renewable alternative to fossil fuels requires a suite of flammability mitigating technologies, particularly robust sensors for hydrogen leak detection and concentration monitoring. To this end, we have developed a class of lightweight optical hydrogen sensors based on a metasurface of Pd nano-patchy particle arrays, which fulfills the increasing requirements of a safe hydrogen fuel sensing system with no risk of sparking. The structure of the optical sensor is readily nano-engineered to yield extraordinarily rapid response to hydrogen gas (<3 s at 1 mbar H2) with a high degree of accuracy (<5%). By incorporating 20% Ag, Au or Co, the sensing performances of the Pd-alloy sensor are significantly enhanced, especially for the Pd80Co20 sensor whose optical response time at 1 mbar of H2 is just ~0.85 s, while preserving the excellent accuracy (<2.5%), limit of detection (2.5 ppm), and robustness against aging, temperature, and interfering gases. The superior performance of our sensor places it among the fastest and most sensitive optical hydrogen sensors.

Pt-Decorated Graphene Gate AlGaN/GaN MIS-HEMT for Ultrahigh Sensitive Hydrogen Gas Detection

Hydrogen fuel has attracted significant attention as an alternative clean energy for hydrogen vehicles and household fuel systems and has been expected to be pervasive. Thus, compact, low-power, and highly sensitive hydrogen sensors capable of being embedded in Internet-of-Things devices are in demand. In this work, an ultrahigh sensitive hydrogen sensor operating at room temperature based on the Pt-decorated graphene (Pt/Gr) gate AlGaN/GaN metal–insulator–semiconductor high electron mobility transistor (MIS-HEMT) is presented. The proposed unique gate structure of island-like Pt on graphene not only modulates the density of 2-D electron gas (2DEG) but also provides efficient diffusion of hydrogen ions into the gate even at very low concentrations ( $\sim 1.6\times 10^{7}$ in a hydrogen concentration of 1000 ppm at room temperature. Upon exposure of at most 1 ppm hydrogen gas, the current increases significantly by a factor of 15.4, exhibiting an unprecedentedly high hydrogen response. Furthermore, the proposed AlGaN HEMT architecture has an outstanding hydrogen selectivity and insensitivity to NH3, H2S, and CO gases at the same time.

Highly sensitive hydrogen sensor based on an in-fiber Mach-Zehnder interferometer with polymer infiltration and Pt-loaded WO3 coating

A highly sensitive fiberized hydrogen sensor based upon Mach-Zehnder interference (MZI) is experimentally demonstrated. The hydrogen sensor consists of an MZI realized by creating an air cavity inside the core of a half-pitch graded-index fiber (GIF) by use of femtosecond laser micromachining. Thermosensitive polymer was filled into the air cavity and cured by UV illumination. Subsequently, the external surface of the polymer-filled MZI was coated with Pt-loaded tungsten trioxide (WO3). The exothermic reaction occurs as Pt-loaded WO3 contacts the target of the sensing, i.e. hydrogen in the atmosphere, which leads to a significant local temperature rise on the external surface of the coated MZI sensor. The sensor exhibits a maximum sensitivity up to -1948.68 nm/% (vol %), when the hydrogen concentration increases from 0% to 0.8% at room temperature. Moreover, the sensor exhibits a rapid rising response time (hydrogen concentration increasing) of ∼38 s and falling response time (hydrogen concentration decreasing) of ∼15 s, respectively. Thanks to its small size, strong robustness, high accuracy and repeatability, the proposed in-fiber MZI hydrogen sensor will be a promising tool for hydrogen leakage tracing in many areas, such as safety production and hydrogen medical treatment.