Hydrogen Sensor Research Articles

Spontaneously decorated palladium nanoparticles on redox active covalent organic framework for chemiresistive hydrogen gas sensing

A rapid hydrogen (H2) sensor operating at room temperature is fabricated using covalent organic framework (COF), namely Pyromellitic dianhydride and tris(4-aminophenyl)amine (PMDA-TAPA), PT COF that has a unique ability to spontaneously reduce Pd2+ into Pd0 nanoparticles without the aid of external reducing agents. The presence of surface redox sites in COF enable the rapid formation of Pd nanoparticles on COF surface under ambient conditions. The generated material, hitherto named as Pd@amicPT portrayed remarkable H2 sensing characteristics with a rare combination of high response % (67.3 ± 1) and rapid response/recovery times (5.3/3.5 s, respectively) for 1 % H2 under ambient conditions. Our results demonstrated appreciable reproducibility, repeatability, and long term stability of sensor that remained unaffected by relative humidity and a high selectivity towards H2. Further, sensor performance is found to be superior when compared to many Pd loaded 2D material based chemiresistive H2 gas sensors.

Steady Output Triboelectric-Electromagnetic Hybrid Generator with Variable Drag Turbine Blades for Natural Wind Energy Harvesting.

In recent years, the triboelectric-electromagnetic hybrid generator (TEHG) has been widely studied. However, the problems of unsteady output and high starting wind speed of traditional TEHG in the wind energy environment have not been effectively solved. This work introduces an innovative solution in the form of a steady output triboelectric-electromagnetic hybrid generator (SO-TEHG) with variable drag turbine blades. The SO-TEHG integrates the energy management circuit to output steady electric energy under random wind conditions. In addition, the integration of variable drag turbine blades with the triboelectric nanogenerator (TENG) reduces the wind speed threshold required for SO-TEHG activation. In comparison to the traditional turbine blades, which necessitate a minimum wind speed of 3 m/s, the SO-TEHG's innovative design allows it to commence power generation at a lower 2 m/s wind speed, producing an additional output of 50 V. This enhanced starting capability in mild breezes positions the SO-TEHG as an ideal power source for applications. In practical farmland settings, experimental results conclusively demonstrate the SO-TEHG's ability to successfully activate soil hygrothermographs and hydrogen sensors. As a steady power source driven by gentle winds, the SO-TEHG holds tremendous promise for advancing smart agriculture.

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.

Temperature and Humidity Effects on SAW Hydrogen Sensor and Compensation Method

Temperature and Humidity Effects on SAW Hydrogen Sensor and Compensation Method

Hydrogen adsorption, desorption, sensor and storage properties of Cu doped / decorated boron nitride nanocone materials: A density functional theory and molecular dynamic study

The hydrogen storage and sensor properties of Cu-modified boron nitride nanocone (BNNC) structure were comprehensively investigated using the density functional theory method (DFT). By replacing nitrogen atoms with copper atoms on the BNNC structure, the hydrogen molecule's adsorption enthalpy and Gibbs free energy values were calculated as −48.6 and −16.9 kJ/mol, respectively. 4 Cu-doped BNNC structure achieved a notable hydrogen storage capacity of 5.38 wt%. The molecular dynamics calculations demonstrate that the structure modified with four Cu atoms maintains its dynamic stability. Furthermore, this study reveals that the desorption temperatures tend to rise with an increase in the number of adsorbed hydrogen molecules, and the average desorption temperature under 1 atm pressure is determined to be 332 K. The changes of work function values after hydrogen adsorption point out that the Cu-modified BNNC has Φ-sensor feature. Overall, Cu-modified BNNC structures show promising potential as hydrogen storage materials in ambient conditions.

A hydrogen sensor based on an acoustic topological material with a coiled structure

A hydrogen sensor based on an acoustic topological material with a coiled structure

Carbon monoxide-resistant hydrogen detection: Pt–melamine–formaldehyde with portable bluetooth in fuel cell

Hydrogen sensors are critical in fuel cell applications, where carbon monoxide (CO) poisoning presents a substantial limitation to sensor longevity. The broad flammability range of hydrogen (from percentages to ppm) underscores the need for precise and efficient detection methods. Traditional approaches employ catalysts, but suffer from limitations such as poor control over catalyst characteristics, limited robustness, and slow response times, under CO poisoning. This study introduces an innovative approach for hydrogen detection in extreme environments by controlling the hydroxyl (OH-) functional groups and significantly decreasing the Pt particle size from 10 nm to 2 nm, which enhances catalytic activity and stability. This enhancement enables wide-range detection and rapid response even under CO poisoning. Our results demonstrate the development of a superior Bluetooth-enabled hydrogen-cap sensor that operates reliably at room temperature in various harsh industrial environments, highlighting its potential applicability and robustness in real-world scenarios.

2D Amino-Functionalized Black Phosphorus: A New Approach to Improve Hydrogen Gas Detection Performance.

In recent years, hydrogen has gained attention as a potential solution to replace fossil fuels, thus reducing greenhouse gas emissions. The development of ever improving hydrogen sensors is a topic that is constantly under study due to concerns about the inherent risk of leaks of this gas and potential explosions. In this work, a new, long-term, stable phosphorene-based sensor was developed for hydrogen detection. A simple functionalization of phosphorene using urea was employed to synthesize an air-stable material, subsequently used to prepare films for gas sensing applications, via the drop casting method. The material was deeply characterized by different techniques (scanning electron microscopy, X-ray diffraction, X-ray photoelectron, and Raman spectroscopy), and the stability of the material in a noninert atmosphere was evaluated. The phosphorene-based sensor exhibited high sensitivity (up to 700 ppm) and selectivity toward hydrogen at room temperature, as well as long-term stability over five months under ambient conditions. To gain further insight into the gas sensing mechanism over the surface, we employed a dedicated apparatus, namely operando diffuse reflectance infrared Fourier transform, by exposing the chemoresistive sensor to hydrogen gas under dry air conditions.

Hydrogen Sensor with a Thick Catalyst Layer Anchored on Polyimide Film

AbstractHydrogen sensors are important in a hydrogen‐driven society to prevent explosions caused by hydrogen leaks into the atmosphere. In previous studies, resistive hydrogen sensors on polymer films have metal oxide nanostructures decorated with novel metals that enable good responses at room temperature. However, the in situ growth process of sensing nanostructures has the disadvantage of ineffective fabrication, particularly when preparing a thick catalyst layer to produce reliable readouts from the catalytic hydrogen combustion. This work presents a catalytic combustion hydrogen sensor with a thick catalyst layer anchored in a UV resin layer on polyimide film. Catalyst anchoring channels are made by UV imprinting with a glass mold. The sensor consists of a sensing electrode and a microheater, both made of Au within an area of 1.2 mm diameter. UV imprinting produces a UV resin layer of 27 µm thick and catalyst anchoring channels of 14 µm deep and 20–30 µm wide, which are filled with Pt/TiO2 as a catalyst. The sensing response is 7.9% for 1% H2 under ambient conditions, and the detection range is 0.1–3% H2. The UV‐resin microstructures can effectively retain a thick catalyst layer to enhance sensitivity, and their low thermal conductivity reduces heat loss.

High-temperature hydrogen sensor based on MOFs-derived Mn-doped In2O3 hollow nanotubes

Developing high-temperature hydrogen (H2) sensors with fast response speed is urgently demanded in harsh application environments, especially for chemical industries and the aerospace field. Herein, we have reported a facile strategy to synthesize Mn-doped In2O3 hollow nanotubes (Mn-In2O3) by solvothermal and annealing route using In-MOFs as precursors. The experimental results indicate that the obtained products possess hollow nanotube structures with plenty of holes and Mn doping greatly boosts the gas-sensing performance of In2O3-based sensors towards H2. In particular, the responses of 3 mol% Mn-In2O3 are 2.57 and 2.3 towards 50 ppm H2 at 360 °C and 400 °C, respectively, which are much higher than those of bare In2O3 hollow nanotubes. Besides, the sensor based on 3 mol% Mn-In2O3 exhibits a low limit of detection (25 ppb), excellent selectivity, rapid response/recovery speed (∼4 and ∼15 s@20 ppm), and excellent stability at high temperature (360 °C). Such enhancement of H2-sensing properties can be put down to the hollow structure derived from In-MOFs and abundant oxygen vacancy defects produced by Mn doping. The Mn-In2O3 hollow nanotubes could be regarded as promising materials for selectively detecting H2 in a wide range of concentrations.

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.

Ultra-selective hydrogen sensors based on CuO - ZnO hetero-structures grown by surface conversion

Synergistic effects of mixed oxides have the potential to improve sensing performances of environmental, domestic and industrial monitoring devices. However, mixed oxides often come in the form of separate particles and are thus addressed separately by the environment, instead of capitalizing on the interface between the metal oxides. This paper describes a new core@shell gas sensing material of tetrapodal zinc oxide with a surface coating of crystalline copper oxide(t-ZnO@CuO). The special surface conversion strategy yields a unique, self-assembled and pinhole-free coating of CuO nanoplatelets. The morphologies, structural, chemical and gas sensing properties of the heterostructure were investigated. To evaluate the sensing properties of the heterostructure, t-ZnO@CuO was fabricated as nanosensors, consisting of one core-shell rod of CuO-coated crystalline ZnO. The single core@shell rod showed high selectivity towards hydrogen already at comparatively low operation temperatures of 150 °C. Computational calculations based on the density functional theory (DFT) have been carried out to understand the interaction of the H2 gas molecule with the surface of the CuO nanostructures. The surface conversion was done wet chemically and is a novel method for generating heterostructures that can be potentially transferred to heterojunctions with unique properties for chemosensors.

Catalytic Activity Evaluation of Molten Salt-Treated Stainless Steel Electrodes for Hydrogen Evolution Reaction in Alkaline Medium

The goal of this research is to fabricate a novel type of highly active porous electrode material, based on stainless steel and dedicated to water electrolyzers. The main novelty of the presented work is the innovative application of the molten salts treatment, which allows the design of a highly developed porous structure, which characterizes significantly higher catalytic activity than untreated steel substrates. The equimolar mixture of NaCl and KCl with 3.5 mol% AlF3 was used as the molten salt. The surface modification procedure includes the deposition of an Al layer with application at the potential of −1.8 V and following dissolution at −0.9 V, to create a porous alloy surface. The cathodic polarization measurements of the prepared porous stainless steel electrodes were measured in a 10 mass% KOH solution. Moreover, the amount of hydrogen generated during constant voltage electrolysis with a hydrogen sensor in situ was also measured. The porous stainless steel alloy showed higher current density at lower potentials in the cathodic polarization compared to untreated stainless steel. The cathodic polarization measurements in alkaline solution showed that the porous 304 stainless steel alloy is an excellent cathode material.

Platinum Decorated Palladium Nanowires for Room‐Temperature Hydrogen Detection

AbstractThe use of hydrogen as an energy carrier will require low‐cost, low‐power hydrogen sensors. Toward this goal, penta‐twinned palladium nanowires (Pd NWs) are synthesized and fabricated sensors from them by drop‐casting. Pd NWs drop‐cast onto an interdigitated electrode (IDE) gave a response of 0.3% to 1 vol.% H2, with response and recovery times of 12 and 20 s, respectively. However, they exhibited a negative response (decreased resistance) at low H2 concentrations. Pd NWs on a paper substrate provided a tenfold higher response to 1 vol.% H2, with response and recovery times of 10 s each, but still exhibited negative response at low H2 concentration. Exposing the Pd NW‐on‐paper sensor to ozone‐generating UV light degraded the PVP used in Pd NW synthesis, eliminating the reverse sensing response, and providing a response of 5% to 1 vol.% H2, with response and recovery times of 15 s. This allowed reliable H2 detection down to 100 ppm H2. Finally, coating the Pd NWs with a small amount of Pt (<5%) reduced the response and recovery times to 5 s by catalyzing H2 dissociation. This work provides a path to low‐cost sensors to enable the safe use of H2 as an energy carrier.

Low temperature hydrogen sensor with high sensitivity based on CeOx thin film

In this work, a 500 nm-thick cerium oxide thin film was prepared by electron beam evaporation. It was found that the deposition of 7 nm thick Pd catalyst was required for obtaining a sensor response to hydrogen. The Pd/CeOx sensing structure has a high response of 5000 towards 25 ppm H2 at a working temperature of 200 °C and exhibits a sensor response of 1.3 at temperatures near ambient. Furthermore, the sensing structure exhibited excellent response/recovery kinetics. The results confirm that the CeOx-based materials are a promising material for the fabrication of room-temperature hydrogen sensors.

Hydrogen Sensing with Palladium-Based Materials: Mechanisms, Challenges, and Opportunities.

Palladium morphologies are prominently used in Hydrogen gas sensing applications owing to their unique characteristics and properties. In this review article, Palladium nanoparticles, thin films, and alloys were designated as the scope of Palladium morphologies. The aim of this review article is to explore Hydrogen sensing using Palladium, focusing on the recent advancements in the field.. The principles underlying Hydrogen sensing mechanisms with Palladium are discussed initially, highlighting the unique properties of Palladium that make it a promising material for this purpose. Special attention is given to the surface interactions and structural modifications that influence the sensitivity and selectivity of Palladium-based sensors The study also addresses key challenges and recent innovations in the field which contribute to the enhancement of Palladium-based Hydrogen sensing capabilities. The current state of research is critically examined to identify gaps in knowledge and future research directions are highlighted. The prospects and challenges associated with the use of Palladium for Hydrogen sensing, emphasizing its pivotal role in advancing sensor technologies for Hydrogen detection are also discussed.

Ultrasensitive and selective hydrogen sensing of SnO2 nanofibers decorated with Pd single atoms

Highly accurate and sensitive hydrogen detection particularly at (sub)ppb level is crucial for large-scale use of green hydrogen energy. However, state-of-the-art hydrogen sensors usually have a ppm-level limit of detection (LOD). In this work, SnO2 nanofibers were decorated with Pd single atoms using a scalable two-step annealing method, which remarkably boosted the H2 sensing properties. The Pd-SnO2 nanofiber sensor exhibited a response of 224 to 1000 ppm H2 at the optimum operation temperature of 300°C, which was 107 times higher than that of SnO2, achieving an LOD as low as 0.6 ppb. Moreover, a fast response time of 8.4 s, excellent selectivity, and humidity tolerance were observed. The superior H2 sensing performance of Pd-SnO2 nanofiber was ascribed to excellent catalysis of Pd single atoms and formation of heterojunction.

High performance H2 sensors based on NiO-SnO2 nanosheets in temperature-pulsed operation mode

Enhancements in the responses of semiconductor gas sensors for hydrogen (H2) are imperative to ensure the safety for industrial processes and fuel cells applications. Alternative to the conventional method of maintaining an optimum isothermal temperature, this study presents a novel technique that sequentially modulates the physisorption and chemisorption processes of the target gas and oxygen species through a temperature-pulsed strategy. This method substantially amplified the electrical responses of a NiO-doped SnO2 gas sensor to H2 vapor. Under the optimum pulsed-heating condition, the sensor achieved a remarkable response of 252–300 ppm H2, which is comparable to or better than that of many existing H2 sensors. The integration of a pulse-driven microheater with a heterojunction-forming sensing layer has led to improved sensitivity, providing additional opportunities for H2 monitoring.

An investigation of glass, ITO, and quartz transparent substrates on Pd/SnO2 hydrogen sensor structure and sensitivity

Hydrogen energy has great potential as a fuel for the future, but its leakage poses a major threat. Thus, our main concern is to detect it very quickly. In this work, we investigate the effect of transparent glass, ITO, and quartz substrates on hydrogen gas sensing properties of magnetron sputter- deposited Pd-capped SnO2 (Pd/SnO2) thin film sensor material. The XRD study reveals that all Pd-capped SnO2 thin films deposited on different substrates has polycrystalline tetragonal structure. Sensors fabricated on quartz substrates exhibit homogeneous grain distributions at the interface, whereas sensors deposited on ITO and glass substrates have randomly size grains distribution at the interface. Sensors deposited on glass and ITO show lower sensitivity compare to sensors fabricated on quartz substrate at a working temperature of 250°C. The Pd/SnO2 sensor @ quartz shown a maximum response of ∼ 9.3 and better stability toward 500 ppm hydrogen gas, and a fast response/recovery time of 30/26 s for 5 ppm hydrogen gas. The sensor @ quartz substrate shows a small reduction in response and baseline at 60% RH. The sensor fabricated on quartz substrate exhibits better selectivity toward hydrogen gas and significant stability for long duration of three months in high humid conditions. The performance of the Pd/SnO2 thin sensor fabricated on quartz proves that the sensor based on average grains have a wide potential for real hydrogen gas monitoring.

Improved performance of a fiber-optic hydrogen sensor based on a controllable optical heating technology.

A novel, to the best of our knowledge, and compact fiber-optic hydrogen sensor based on light intensity demodulation and controllable optical heating technology is proposed and experimentally investigated. This system employs three photodetectors for optic signal transformation. The first PD is used to receive a little fraction of the amplified spontaneous emission (ASE) for calibration, and the second PD is utilized to detect optic signal reflected by a single mode fiber deposited with WO3-Pd2Pt-Pt composite film. The last PD is utilized to receive the optical power reflected by the short fiber Bragg grating (SFBG) with a central wavelength located in a steep wavelength range (the intensity decreases approximately linearly with the increase of the wavelength) of the ASE light source. A 980 nm laser and proportion integration differentiation (PID) controller were employed to ensure the hydrogen sensitive film working at an operating temperature of 60°C. This sensing system can display a quick response time of 0.4 s toward 10,000 ppm hydrogen in air. In addition, the detection limit of 5 ppm in air can be achieved with this sensing system. The stability of this sensor can be greatly enhanced with a controllable optical heating system, which can greatly promote its potential application in various fields.