Precisely Control Relationship between Sulfur Vacancy and H Absorption for Boosting Hydrogen Evolution Reaction

Ef fective and robust catalyst is the core of water splitting to produce hydrogen.Here, we report an anionic etching method to tailor the sulfur vacancy(VS) of NiS_(2) to further enhance the electrocatalytic performance for hydrogen evolution reaction(HER). With the VS concentration change from 2.4% to 8.5%, the H* adsorption strength on S sites changed and NiS_(2)-VS 5.9% shows the most optimized H* adsorption for HER with an ultralow onset potential(68 m V) and has long-term stability for 100 h in 1 M KOH media. In situ attenuated-total-reflection Fourier transform infrared spectroscopy(ATR-FTIRS) measurements are usually used to monitor the adsorption of intermediates. The S-H* peak of the Ni S_(2)-VS 5.9% appears at a very low voltage, which is favorable for the HER in alkaline media. Density functional theory calculations also demonstrate the Ni S_(2)-VS 5.9% has the optimal |ΔG^(H*)| of 0.17 e V. This work offers a simple and promising pathway to enhance catalytic activity via precise vacancies strategy.

Hydrogen Gas Sensor Based on Nanocrystalline SnO_2 Thin Film Grown on Bare Si Substrates

In this paper, high-quality nanocrystalline SnO_2 thin film was grown on bare Si(100) substrates by a sol–gel method. A metal–semiconductor–metal gas sensor was fabricated using nanocrystalline SnO_2 thin film and palladium(Pd)metal. The contact between Pd and nanocrystalline SnO_2 film is tunable. Ohmic barrier contact was formed without addition of glycerin, while Schottky contact formed by adding glycerin. Two kinds of sensor devices with Schottky contact were fabricated(Device 1: 8 h, 500 °C; Device 2: 10 h, 400 °C). The room temperature sensitivity for hydrogen(H_2) was120 and 95 % in 1000 ppm H_2, and the low power consumption was 65 and 86 l W for two devices, respectively. At higher temperature of 125 °C, the sensitivity was increased to 195 and 160 %, respectively. The sensing measurements were repeatable at various temperatures(room temperature, 75, 125 °C) for over 50 min. It was found that Device 1 has better sensitivity than Device 2 due to its better crystallinity. These findings indicate that the sensors fabricated on bare Si by adding glycerin to the sol solution have strong ability to detect H_2 gas under different concentrations and temperatures.

Phase composition,conductivity,and sensor properties of cerium-doped indium oxide

The hydrothermal synthesis of In_(2)O_(3)and CeO_(2)–In_(2)O_(3)is investigated as well as the properties of sensor layers based on these compounds.During the synthesis of In_(2)O_(3),intermediate products In(OH)_(3)and InOOH are formed,which are the precursors of stable cubic(c-In_(2)O_(3))and metastable rhombohedral(rh-In_(2)O_(3))phases,respectively.A transition from c-In_(2)O_(3)to rh-In_(2)O_(3)is observed with the addition of CeO_(2).The introduction of cerium into rh-In_(2)O_(3)results in a decrease in the sensor response to hydrogen,while it increases in composites based on c-In_(2)O_(3).The data on the sensor activity of the composites correlate with XPS results in which CeO_(2)causes a decrease in the concentrations of chemisorbed oxygen and oxygen vacancies in rh-In_(2)O_(3).The reverse situation is observed in composites based on c-In_(2)O_(3).Compared to In_(2)O_(3)and CeO_(2)–In_(2)O_(3)obtained by other methods,the synthesized composites demonstrate maximum response to H_(2)at low temperatures by 70–100℃,and have short response time(0.2–0.5 s),short recovery time(6–7 s),and long-term stability.A model is proposed for the dependence of sensitivity on the direction of electron transfer between In_(2)O_(3)and CeO_(2).

Preparation of Regenerated Silk Fibroin Hybrid Fibers with Hydrogen Peroxide Sensing Properties by Wet Spinning

Silk is widely used in the production of high-quality textiles.At the same time,the amount of silk textiles no longer in use and discarded is increasing,resulting in significant waste and pollution.This issue is of great concern in many countries where silk is used.Hydrogen peroxide as a naturally occurring compound is an important indicator of detection in both biology and the environment.This study aims to develop a composite fiber with hydrogen peroxide-sensing properties using discarded silk materials.To achieve this goal,firstly,polydopamine(PDA)was used to encapsulate the ZnFe_(2)O_(4) NPs to achieve the improvement of dispersion,and then regenerated silk fibroin(RSF)and PDA@ZnFe_(2)O_(4)/RSF hybrid fibers are prepared by wet spinning.Research has shown that PDA@ZnFe_(2)O_(4)/RSF demonstrates exceptional sensitivity,selectivity,and stability in detecting hydrogen peroxide,while maintaining high mechanical strength.Furthermore,the complete hybridization of PDA@ZnFe_(2)O_(4) with silk fibroin not only results in the combination of the durability of silk fibroin and PDA@ZnFe_(2)O_(4)’s rigidity,ensuring a reliable service life,but also makes PDA@ZnFe_(2)O_(4)/RSF exhibit excellent catalytic activity and biocompatibility.Therefore,the composite fiber exhibits exceptional mechanical properties and reliable hydrogen peroxide sensing capabilities,making it a promising material for biological and medical applications.

Morphology control of aluminum nitride(AlN)for a novel high-temperature hydrogen sensor

Hydrogen is a promising renewable energy source for fossil-free transportation and electrical energy generation.However,leaking hydrogen in high-temperature production processes can cause an explosion,which endangers production workers and surrounding areas.To detect leaks early,we used a sensor material based on a wide bandgap aluminum nitride(AlN)that can withstand a high-temperature environment.Three unique AlN morphologies(rod-like,nest-like,and hexagonal plate-like)were synthesized by a direct nitridation method at 1400℃usingγ-AlOOH as a precursor.The gas-sensing performance shows that a hexagonal plate-like morphology exhibited p-type sensing behavior and showed good repeatability as well as the highest response(S=58.7)toward a 750 ppm leak of H2 gas at high temperature(500°C)compared with the rod-like and nest-like morphologies.Furthermore,the hexagonal plate-like morphology showed fast response and recovery times of 40 and 82 s,respectively.The surface facet of the hexagonal morphology of AlN might be energetically favorable for gas adsorption–desorption for enhanced hydrogen detection.

Research Surveys of Electrochemical Sensors for in-situ Determining Hydrogen in Steels

The principle, construction and application of two types of electrochemical sensors-amperometric and potentiometric are surveyed. Both types of sensors are very sensitive to changes in temperature. The accuracy of hydrogen measurement depends on both the precision of sensors developed and the reliable technique of installation and security of sensors. The two types of sensors have been used for in-situ determining hydrogen permeated in steels owing to a corrosive reaction, a hydrogen gas circumstance at elevated temperatures and high pressure or also a pretreatment process such as pickling and plating process, etc.

Calibration of Hydrogen Peroxide Vapour Sensor

Hydrogen Peroxide vapour is becoming more popular to use as a method of decontamination, particularly for medical equipment and enclosures. It is highly effective in terms of microbiological kill rates and has a variety of uses in healthcare. Although it is environmentally acceptable as it spontaneously decomposes into water and oxygen, concentration of hydrogen peroxide in the air needs to be monitored and controlled. A method of calibrating hydrogen peroxide vapor sensors is described which is based on the concentration of hydrogen peroxide in saturated vapour over a solution in water at a defined temperature. The saturated vapour is generated by bubbling dry air into a solution of hydrogen peroxide at a defined concentration and temperature. A vapour at a concentration of 0.7 ppm was produced and used to successfully calibrate a hydrogen peroxide sensor.

Simple Planar Structure Hydrogen Gas Sensor Device with Large Response

Hydrogen gas sensor device with simple planar structure based on p^+ silicon substrate with n-type epi-layer was fabricated only by using a lift-off technique of an evaporated metal film.The device consists of Ohmic source and drain electrodes and platinum Schottky gate electrode.This sensor device has a little similar property as FET.Current-voltage characteristics between the source and drain of the device are sensitive to hydrogen gas.The voltage difference between in hydrogen ambient and oxygen ambient is about 2.3 volts for a constant current of 0.9 mA.The device can detect 0.4% hydrogen gas in air.Based on oxidation reaction of hydrogen on the surface of the platinum gate,hydrogen sensitivity of the device changes by the coexisting oxygen concentration.Electrons flow in the buried channel formed between the gate electrode and the p^+n junction.It was confirmed that the gate bias influences the properties.The current-voltage property changes also depending on the wiring method.

Micro Hydrogen Sensor Based on Pd-Ag Nanofilm

In this paper,palladium-silver (Pd-Ag) system was studied for hydrogen sensing.Nanofilm of Pd-Ag was fabricated on a porous ceramic substrate through a combination of microfabrication techniques.The electric resistance of the zigzag-shaped microstructure was measured toward hydrogen concentration change.The sensing element demonstrates high sensitivity,fast response and fast recovery to hydrogen.The Pd-Ag film was characterized by scanning electron microscopy (SEM) equipped with X probe to correlate its physical and chemical properties to its sensing performance.The present sensor is very promising for room temperature hydrogen leakage detection and related applications.The temperature effect on the sensing performance of the metal film was also investigated.

Preparation of Co/S co-doped carbon catalysts for excellent methylene blue degradation

S and Co co-doped carbon catalysts were prepared via pyrolysis of MOF-71 and thiourea mixtures at 800℃at a mass ratio of MOF-71 to thiourea of 1:0.1 to effectively activate peroxymonosulfate(PMS)for methylene blue(MB)degradation.The effects of two different mixing routes were identified on the MB degradation performance.Particularly,the catalyst obtained by the alcohol solvent evaporation(MOF-AEP)mixing route could degrade 95.60%MB(50 mg/L)within 4 min(degradation rate:K=0.78 min^(-1)),which was faster than that derived from the direct grinding method(MOF-DGP,80.97%,K=0.39 min^(-1)).X-ray photoelectron spectroscopy revealed that the Co-S content of MOF-AEP(43.39at%)was less than that of MOF-DGP(54.73at%),and the proportion of C-S-C in MOF-AEP(13.56at%)was higher than that of MOF-DGP(10.67at%).Density functional theory calculations revealed that the adsorption energy of Co for PMS was -2.94 eV when sulfur was doped as C-S-C on the carbon skeleton,which was higher than that when sulfur was doped next to cobalt in the form of Co-S bond(-2.86 eV).Thus,the C-S-C sites might provide more contributions to activate PMS compared with Co-S.Furthermore,the degradation parameters,including pH and MOF-AEP dosage,were investigated.Finally,radical quenching experiments and electron paramagnetic resonance(EPR)measurements revealed that ^(1)O_(2)might be the primary catalytic species,whereas·O~(2-)might be the secondary one in degrading MB.

Amperometric Sensors for Determination of Hydrogen Peroxide Based on Electron Transfer Between Horseradish Peroxidase and 1，1＇－Dimethylferrocene

hydrogen peroxide electrode with 1,1'-dimethylferrocene(DMFc)used as an electron transfer mediator has been described.Using Nafion, DMFc was modified on a glassy carbon electrode(GCE)surface,and horseradish peroxidase(HRP)was then immobiliged on the DMFc-Nafion film,forming a HRp-DMFc-Nafion modi- fied electrode. The chracteristics of the sensor has been shown by cyclic voltam- metry and constant potential measurements,The sensor responds fastly to hydro- gen peroxide,the time required to reach 95%of the steady-state current is less than 50s. The sensor displays a sensitive catalytic current response to hydrogen peroxide and can be operated at a potential range in which the oxidation of common interfering species,such as ascorbic acid and uric acid,does not occur. The sensor is stable for 20 days and its detection limit is 1 μmol/L.

Electrodeposited Cobalt-Iron Alloy Thin-Film for Potentiometric Hydrogen Phosphate-Ion Sensor

A cobalt-iron alloy thin-film electrode-based electrochemical hydrogen-phosphate-ion sensor was prepared by electrodepositing on an Au-coated Al2O3 substrate from an aqueous solution of metal-salts. The use of a cobalt-iron alloy electrode greatly improved the hydrogen-ion sensor response performance, i.e., the sensor worked stably for more than 7 weeks and showed a quick response time of several seconds. Among the cobalt and iron alloy systems tested, the electrodeposited Co58Fe42 thin-film electrode showed the best EMF response characteristics, i.e., the sensor exhibited a linear potentiometric response to hydrogen-phosphate ion at the concentration range between 1.0 × 10–5 and 1.0 × 10–2 M with the slope of –43 mV/decade at pH 5.0 and at 30℃. A sensing mechanism of the Co-based potentiometric hydrogen-phosphate ion sensor was proposed on the basis of results of instrumental analysis.

New Applications of the Noise Spectroscopy for Hydrogen Sensors

Peculiarities of the low-frequency noise spectroscopy of hydrogen gas sensors made on MgFeO4 n-type porous semiconductor covered by the palladium catalytic nanosize particles are investigated. Behavior of the low-frequency noise spectral density and its exponent value from sensitive layer thickness in the frequency range 2 - 300 Hz are analyzed. Sensitivity of the sensor calculated by the noise method is several tenth times higher as compared with the resistive method. It is shown that besides of the well-known applications, noise spectroscopy can be also used for definition of the unknown thickness of gas sensitive layer, for definition of the sensitive layer subsurface role in the formation of the low-frequency noises and for definition of the intensity of trapping-detrapping processes of the gas molecules.

Detection of Combustible Gases by Semiconductor Sensors──Rapid Separation of Hydrogen Sulphide with β，β＇－oxydipropionitrile

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Low-Temperature Formation of a WO₃Thin Film by the Sol-Gel Method Using Photo-Irradiation and Fabrication of a Flexible Hydrogen Sensor

Hydrogen has been recently attracted much attention with respect to high energy-conversion efficiency and low environmental burden. However, hydrogen gas is dangerous due to an explosive gas and a fast combustion rate. Therefore, the development of hydrogen sensor with high accuracy and reliability that can detect hydrogen easily is required. Especially, a flexible hydrogen sensor is useful because it has a high degree of freedom with respect to the shape of location in which the sensor is to be located. A flexible hydrogen sensor—namely, a WO3 thin film formed on a PET film by the sol-gel method using photo irradiation—based on gasochromism of WO3 was developed. By irradiating a thin film, which was prepared by using WO3 precursor solution synthesized by the sol-gel method, with ultraviolet rays, a high-purity WO3 film could be prepared on PET at low temperature. The sensor was structured as a polystyrene (PS) film containing palladium (Pd) laminated on a WO3 film. The WO3 layer was porous, so the PS containing Pd atoms solution penetrated the WO3 layer. WO3 reacted with hydrogen gas and instantly turned blue as the transmittance of the WO3 layer changed. The sensor showed high reactivity even for hydrogen concentration below 4% (1%, 0.5%, 0.25%, and 0.1%), which was the lower limit of hydrogen ignition, and a linear relationship between hydrogen concentration and change in transmittance was found. Moreover, the resistance of the WO3 film significantly and instantaneously changed due to hydrogen-gas exposure, and the hydrogen concentration and resistance change showed a linear relationship. It is therefore possible to quantitatively detect low concentrations of hydrogen by using changes in transmittance and resistance as indices. Since these changes occur selectively under hydrogen at room temperature and normal pressure, they form the basis of a highly sensitive hydrogen sensor. Since the developed sensor is flexible, it has a high degree of freedom with respect to the shape of location in which the sensor is to be

Effect of Exogenous Hydrogen Sulfide(H_2S) on the Electrocardiogram(ECG) of Rats Generally Anaesthetized by Zoletil

Hydrogen sulfide （H2S） is the third gaseous signaling molecule discovered in recent years, and plays an important physiological role in the cardivascular system. To explore the effects of different doses of exogenous H2S on the electrocardiogram （ECG） of rats generally anesthetized by zoletil, different doses of NariS solution were used for the intervention of intraperitoneal injection 20 rain before the zoletil anesthesia. The ECGs of rats from each treatment group during the time range of 10^th-50^th min were determined under general anesthesia, and then were compared with those from the control group. The results showed that exogenous H2S could significantly reduce the Q-T interval time limit, thus played a role in slowing tachycardia or arrhythmia and other anomalies, thereby protecting the heart. S-T segment and T segment evaluation values were significantly reduced, which might be associated with bradycardia.

S型异质结光催化剂的研究进展

光催化技术具有合成过程简便、反应条件易控制、充分利用太阳能且无二次污染等突出优势,在处理环境污染问题和缓解全球能源短缺等方面具有广阔的应用前景。然而,由于光生载流子低的转移和分离效率,实际的光化学转换效率提升受到了限制。新兴的S型异质结光催化剂由于其在空间上实现了光生载流子的有效转移分离并展现出强的氧化还原能力,在太阳燃料制备和环境治理领域受到了广泛关注和研究。综述了异质结光催化剂的发展历程和S型异质结的基本原理及在各领域中的应用。最后,总结了S型异质结光催化剂的突出优势,并提出S型异质结光催化剂的发展前景和面临的挑战,为开发具备高效光催化活性的新型异质结光催化剂提供思路和参考。

Radial Basis Function Neural Networks-Based Modeling of the Membrane Separation Process: Hydrogen Recovery from Refinery Gases

Membrane technology has found wide applications in the petrochemical industry, mainly in the purification and recovery of the hydrogen resources. Accurate prediction of the membrane separation performance plays an important role in carrying out advanced process control （APC）. For the first time, a soft-sensor model for the membrane separation process has been established based on the radial basis function （RBF） neural networks. The main performance parameters, i.e, permeate hydrogen concentration, permeate gas flux, and residue hydrogen concentration, are estimated quantitatively by measuring the operating temperature, feed-side pressure, permeate-side pressure, residue-side pressure, feed-gas flux, and feed-hydrogen concentration excluding flow structure, membrane parameters, and other compositions. The predicted results can gain the desired effects. The effectiveness of this novel approach lays a foundation for integrating control technology and optimizing the operation of the gas membrane separation process.

Synthesis of a New Rigid Bicyclic AMPP Ligand (TIAMPP) and Application in Asymmetric Hydrogenation

The new rigid bicyclic AMPP（（S）-TIAMPP） has been synthesized from the corresponding Ticol and Ph2PCI. The application of （S）-TIAMPP in Rh-catalyzed asymmetric hydrogenation of α-dehydroamino acids derivatives has been examined. Up to 93% ee was obtained.

MoS2/Zn3In2S6 composite photocatalysts for enhancement of visible light-driven hydrogen production from formic acid

Enhancing the separation efficiency of photogenerated carriers is propitious for the promotion of photocatalytic hydrogen production from formic acid decomposition.Herein,MoS2/Zn3In2S6(MoS2/ZIS6)composite photocatalysts containing varying mass percentages of MoS2 were obtained by a straightforward synthetic method.The results confirmed that MoS2,as a cocatalyst,markedly promoted the photogenerated charge separation efficiency and visible light-driven hydrogen production activity of ZIS6(λ>400 nm).Specifically,the as-prepared 0.5%MoS2/ZIS6 photocatalyst exhibited the highest photocatalytic hydrogen production rate(74.25μmol·h^-1),which was approximately 4.3 times higher than that of ZIS6(17.47μmol·h^-1).The excellent performance of the 0.5%MoS2/ZIS6 photocatalyst may be due to the fact that MoS2 has a low Fermi energy level and can thus enrich photogenerated electrons from ZIS6,and furthermore reduce H+derived from formic acid,to form hydrogen.The structure and morphology of the MoS2/ZIS6 photocatalysts and the reactive species were determined by X-ray diffraction,transmission electron microscopy,and field emission scanning electron microscopy,among others;a plausible mechanistic rationale is discussed based on the results.