Role Of Gas Research Articles

Ultrafast-response H2S MEMS gas sensor based on double phase In2O3 monolayer particle film

The regulation of crystal structure plays a crucial role in gas sensing. In this work, by precisely controlling the annealing temperature, we first synthesized rhombohedral corundum-type In2O3 (h-In2O3), cubic bixbyite-type In2O3 (c-In2O3) and double phase In2O3 (c/h-In2O3). The c/h-In2O3 possesses the heterostructures of double phases, the abundant oxygen vacancies (61.1 %), and the more adsorbed oxygen (35.9 %). Subsequently, by self-assembly method, the sensors with one monolayer In2O3 particle film were successfully fabricated. The c/h-In2O3 sensor shows excellent H2S sensing performances with high response of 54.4 (50 ppm), extremely fast response time of 3.3 s and low limit of detection (LOD) of 20 ppb at 160 °C. The reasons for the ultrafast response of the sensor were unveiled through the comparison experiment of 4 layers particle film sensor and the theoretical analysis. Additionally, the outstanding sensing performance could be attributed to the abundant oxygen vacancies, the double phase heterojunction and the monolayer particle film. This work provides a new idea for designing micro-electro-mechanical system (MEMS) gas sensors with high sensitivity, extremely fast response, low power consumption and high level of integration.

Investigation of a highly efficient foaming mixture compromising cationic Gemini-zwitterionic-anionic surfactants for gas well deliquification

Abstract Foamers with high resistance to condensate, salinity and high temperature play a crucial role in gas well deliquification. In this study, we developed an efficient foaming mixture containing a Gemini surfactant (CAGB), a betaine surfactant (CAPB) and sodium lauroyl glutamate (SLG), which exhibited excellent foaming performance (at a molar ratio of 3:3:4 and a dosage of 20 mmol L−1) with a foam volume of 440 mL and a half-life of 11 min. The optimized CAGB/CAPB/SLG mixture showed exceptional liquid unloading and foaming ability under high methanol (up to 40 vol.%) and condensate (up to 50 vol.%) content conditions. Trisodium aminotriacetate (NTA) facilitated the liquid unloading performance at a salinity of 90 g L−1. With 10 vol.% methanol, the liquid unloading rate of CAGB/CAPB/SLG foam at 90 °C could be increased to 90 %. Furthermore, surface tension and morphology analysis confirmed the presence of synergy within the CAGB/CAPB/SLG mixture in foaming, foam stabilizing and liquid unloading ability.

Carbon Material-Reinforced Polymer Composites for Bipolar Plates in Polymer Electrolyte Membrane Fuel Cells.

Bipolar plates (BPs) are one of the most important components of polymer electrolyte membrane fuel cells (PEMFCs) because of their important role in gas and water management, electrical performance, and mechanical stability. Therefore, promising materials for use as BPs should meet several technical targets established by the United States Department of Energy (DOE). Thus far, in the literature, many materials have been reported for possible applications in BPs. Of these, polymer composites reinforced with carbon allotropes are one of the most prominent. Therefore, in this review article, we present the progress and critical analysis on the use of carbon material-reinforced polymer composites as BPs materials in PEMFCs. Based on this review, it is observed that numerous polymer composites reinforced with carbon allotropes have been produced in the literature, and most of the composites synthesized and characterized for their possible application in BPs meet the DOE requirements. However, these composites can still be improved before their use for BPs in PEMFCs.

Exploring the Contribution of Intelligent Nanomaterials in Gas Sensing

AbstractGas sensors are crucial in various industries like chemicals, food processing, pharmaceuticals, health monitoring through breath analysis, as well as in household and environmental monitoring to ensure human safety. Chemo‐resistive gas sensors based on metal oxides convert gas information into electrical signals by interacting with adsorption and desorption processes. For metal oxide semiconductor gas sensors, sensitivity and selectivity enhancements are achieved through doping, functionalization, composite formations, heterojunction creation, and morphological adjustments. The formation of heterojunctions notably boosts the efficacy of the sensing material, leveraging synergistic effects to reinforce adsorption rates, catalytic activity acceleration, and the depletion interface for electrons and holes. Over the past few decades, nanomaterials have played a critical role in gas sensing applications. They have enabled the detection of a wide array of harmful and polluting gases, as well as volatile organic compounds serving as disease biomarkers. Additionally, incorporating heterostructure nanomaterials into heterojunctions significantly impacts sensing performance and detection speed. This review discussed various types of gas sensing devices, categorizing them based on the sensing elements employed, each possessing its own set of unique advantages and disadvantages. Nevertheless, the review underscored the importance of several key parameters and factors that influence the performance of gas sensors. Additionally, recent advancements in the utilization of nanomaterial composites for gas sensor applications, particularly in the detection of gases such as ammonia, hydrogen sulphide, and sulphur dioxide vapours, were discussed. Furthermore, the review highlights recent research endeavours and fundamental parameters, including sensitivity, detection limits, selectivity, response times, and recovery times.

Effect of kinetic properties of zeolites on the gas-sensing performance of zeolite-covered SnO2 sensors

ABSTRACT Zeolite additional layers coating on metal oxide surfaces to improve the selectivity and response values of the sensors are effective and widely used. The specific adsorption and diffusion of gas molecules in the zeolite are recognised to play an important role in gas sensing improvement. In this work, the adsorption and diffusion behaviours of formaldehyde and acetone in H-Y and H-A zeolites were calculated by Monte Carlo and molecular dynamics simulations. The loading of acetone is greater than formaldehyde in these two kinds of zeolites under the same temperature and pressure, and the water load is lower. The simulation results show that the effects of the nature of the guest molecule and steric hindrance of the diffusing molecule on diffusivity are significant. The diffusivity in H-A zeolite decreases by several orders of magnitude than that in H-Y zeolite However, in H-A zeolite, the internal diffusion dominates, and only the smaller diameter formaldehyde can diffuse between the pores, which is beneficial to improving the sensing properties of formaldehyde. In addition, in the competition diffusion with water molecules, formaldehyde dominates than acetone. The H-Y/SnO2 and H-A/SnO2 sensors were prepared to verify the reliability of the molecular simulations. Research highlights The adsorption and diffusion behaviour of formaldehyde and acetone in H-Y and H-A zeolites were investigated using molecular simulation. Molecular diameter mainly influences the kinetic behaviour. The sensitisation mechanism of H-Y/SnO2 sensor to acetone and H-A/SnO2 sensor to formaldehyde was proved. Focuses on the relationship between gas-sensing the performance of zeolite-covered SnO2 sensors and the adsorption.

Microbubble formation by flow focusing: role of gas and liquid properties, and channel geometry

Microfluidic flow focusing is a versatile method for the production of monodisperse microbubbles for biomedical applications involving ultrasound. Existing studies propose several theoretical models to predict bubble size and production rate as a function of the liquid and gas flow rate. Yet, they typically do not include physical fluid parameters such as density, viscosity and surface tension. Here, we present an exhaustive experimental and numerical investigation of the influence of physical properties of the gas and liquid, and of the channel geometry on bubble size and production rate. We find a particularly strong effect of (i) gas density on the production rate and (ii) liquid viscosity on the bubble size. We further discuss our findings within the context of existing theoretical models to reflect on gaps in our current understanding of the fluid mechanics of bubble formation by flow focusing.

Ti3C2Tx MXene-SnO2 nanocomposite for superior room temperature ammonia gas sensor

Recently MXenes become the focus of emerging 2D layered materials family owing to their unique properties and promising potential in gas detection. However, the sensitivity and the stability of the pristine MXenes are poor due to their high carrier concentration and abundant active sites on the surface. Herein, superior NH3 sensors with high response and stability were successfully obtained by wrapping the SnO2 nanoparticles on Ti3C2Tx MXene nanosheets via a facile hydrothermal method. The nanostructures, morphologies, and compositions of the Ti3C2Tx MXene-SnO2 composite were systematically characterized by XRD, FTIR, SEM, TEM and XPS techniques. Results show that SnO2 nanoparticles with high specific surface area are uniformly dispersed on the Ti3C2Tx MXene surface, constructing loose heterostructure, which plays a crucial role in gas adsorption/desorption. In the Ti3C2Tx MXene-SnO2 heterostructure, the Ti3C2Tx MXene acts as a signal amplification channel for electron transfer in gas sensing reaction. The sensors exhibit excellent NH3 gas detection at room temperature. Response as high as 75% is observed for 500 ppm NH3 gas. Fast response and recovery times are also obtained, 109 and 342 s, respectively. Moreover, the sensing performances of the Ti3C2Tx MXene-SnO2 composite with various MXene ratios were systematically studied. It is found out that the 16.8%Ti3C2Tx-SnO2 based sensor shows the highest sensitivity in 10∼100 ppm range, and the 9.1%Ti3C2Tx-SnO2 based sensor exhibits the widest detection range. In addition, the selectivity and repeatability were also studied, revealing high selectivity and stability of the Ti3C2Tx MXene-SnO2 composite. Thus, Ti3C2Tx-SnO2 composite provides a new material to design and develop superior room temperature NH3 gas sensors.

Lessons from the energy crisis of an energy exporter

The Eastern Australian gas crisis of Winter 2022 was particularly perverse in that it briefly saw wholesale prices exceed those for spot liquefied natural gas (LNG) imports into North Asia and twice triggered the Gas Supply Guarantee Mechanism. This paper provides an analysis of the drivers behind this crisis that reveals how grids such as the National Electricity Market (NEM), during a renewables build-up coupled with a coal phase-down with ageing coal-fired capacity, will continue to be vulnerable to seasonal shocks and wide intra-day spreads in the medium term. We also highlight how the role of gas in enabling further uptake for renewables is not to be taken for granted, drawing on lessons from intermittency in other regions, and that only through rapid decarbonisation of the electricity sector can we begin electrification of direct use sectors. Within the Eastern Australian context, this calls for more flexible gas supply and investments to mitigate transportation bottlenecks as the regions’ centre of supply shifts towards Queensland in the years ahead. We conclude that in the absence of a game-changing development in the sector, such as clear policy to support significant new developments in domestic production, we expect structurally higher domestic prices and seasonal domestic shortages that will create an overhang on LNG exporters, complicating their already uneasy relationship with the domestic market.

NO2 Physical-to-Chemical Adsorption Transition on Janus WSSe Monolayers Realized by Defect Introduction.

As is well known, NO2 adsorption plays an important role in gas sensing and treatment because it expands the residence time of compounds to be treated in plasma-catalyst combination. In this work, the adsorption behaviors and mechanism of NO2 over pristine and Se-vacancy defect-engineered WSSe monolayers have been systematically investigated using density functional theory (DFT). The adsorption energy calculation reveals that introducing Se vacancy acould result in a physical-to-chemical adsorption transition for the system. The Se vacancy, the most possible point defect, could work as the optimum adsorption site, and it dramatically raises the transferred-electron quantities at the interface, creating an obviously electronic orbital hybridization between the adsorbate and substrate and greatly improving the chemical activity and sensing sensitivity of the WSSe monolayer. The physical-to-chemical adsorption transition could meet different acquirements of gas collection and gas treatment. Our work broadens the application filed of the Janus WSSe as NO2-gas-sensitive materials. In addition, it is found that both keeping the S-rich synthetic environments and applying compression strain could make the introduction of Se vacancy easier, which provides a promising path for industrial synthesis of Janus WSSe monolayer with Se vacancy.

CROATIA’S ENERGY FUTURE AND GAS SUPPLY

The characteristics of the contemporary energy markets are analyzed, as well the use of oil, gas and electricity. Europe’s energy supply, the new cycle of the politicization of energetics, the role of gas in European energetics, and several contemporary dilemmas regarding European energetics following the consolidation of the energy companies via mergers and takeovers are discussed. The shares of energy consumption in Croatia, the share of gas, the position of natural gas as the basis for the future development of Croatian energetics as well as the relative cost of energy sources and the price of gas in Croatia are analyzed. It is concluded that the period of cheap energy is behind us and that energy projects can and must not only be the means for insuring the necessary amounts energy for future economic development but also an opportunity for the development of Croatian companies.

ApGA20ox1, a key gibberellin biosynthesis gene, regulates somatic embryogenesis and plant height in Agapanthus praecox

Agapanthus praecox is cultivated worldwide as an ornamental plant, and a dwarf ideotype has become more popular due to its superior lodging resistance and its suitability for use in cut flowers. The main bioactive gibberellin (GA) controlling scape height in A. praecox is GA4. A GA biosynthesis gene, ApGA20ox1, controls GA4 biosynthesis in this species. Here, we report the development of an A. praecox dwarf phenotype, which was generated by targeted suppression of the biosynthetic pathway for GAs. We utilized Agrobacterium-mediated genetic transformation using embryogenic callus with RNA interference (RNAi) to selectively reduce the expression of the ApGA20ox1 gene. Interestingly, suppression of ApGA20ox1 resulted in poor somatic embryogenesis potential in A. praecox, which was accompanied by a higher accumulation of hydrogen peroxide and poorer catalase activity. Subsequently, the RNAi plantlets showed lower GA levels, leading to inhibition of cell longitudinal size in leaves, which reduced plant height. Furthermore, the dwarf (RNAi) plantlets accumulated higher levels of saccharides and plant hormones such as indole acetic acid (IAA) and abscisic acid (ABA) than the wild type accumulated. However, the levels of endogenous hormones such as GAs, brassinosteroids (BRs), cytokinins (CTKs), which respond to cell proliferation and cell expansion, were significantly decreased. Isobaric tags for relative and absolute quantification (iTRAQ) proteomics revealed that differentially accumulated proteins (DAPs) were enriched differently between control and RNAi plantlets in the categories of cell wall, hormone metabolism, carbohydrate metabolism and stress response. This study provides new insights into the role of GAs in the process of somatic embryogenesis and plant height control in A. praecox.

The mechanism of gibberellins treatment suppressing kiwifruit postharvest ripening processes by transcriptome analysis

Gibberellins (GAs) control numerous processes in plants, including fruit ripening. However, the role of GAs in kiwifruit ripening is not well characterized. Here, we noticed that GA3 treatment in postharvest kiwifruit delayed the ripening process and many physiological traits were detected such as firmness, starch/total soluble solid content, cell-wall components (pectin, cellulose and hemicellulose), ethylene and ester production, and ascorbic acid (vitamin C) concentration. Transcriptome analysis supplied a molecular basis for investigating the inhibiting mechanism of GA3 and metabolic variations during kiwifruit ripening. A total of 3116 differently expressed genes (DEGs) were identified, including 51 genes involved in plant hormone signal transduction pathways and 36 structural genes related to these physiological traits. 16 major DEGs were analyzed by real-time PCR during the whole storage period. The expression of most of them was significantly suppressed by GA3 treatment, such as two ethylene biosynthesis genes (ACOs ), two β-amylase (BAMs), five cell-wall modification genes, one GA2ox, and one GA receptor GID1, whereas the expression of Actinidia29942 (JAZ) was enhanced by GA3 treatment. Correlation analysis between multiple physiological indicators and candidate genes showed that GA3 could regulate kiwifruit postharvest ripening effectively and comprehensively. Together, these GA-responsive genes may play important roles in controlling kiwifruit ripening, and GA treatment could be a promising approach for the preservation of postharvest kiwifruit.

Metal–Organic Framework-Derived Co-Doped ZnO Nanostructures Anchored on N-Doped Carbon as a Room-Temperature Chemiresistive Hydrogen Sensor

The impending need to utilize H2 for multiple applications has surged the need to develop H2 sensors. Development of selective and rapid room-temperature H2 sensors is an uphill task without the doping of precious metals (Pd, Pt, and Au) in semiconductor metal oxide (SMO) sensors. Nanostructure of the SMOs could play a decisive role in gas sensing properties of the material. In this study, metal–organic framework (MOF)-derived Co–ZnO anchored on nitrogen-doped carbon (Co–ZnO–N/C) nanomaterial has been demonstrated as an effective rapid room-temperature H2 sensor. The pyrolysis of monometallic ZIF-8 (Zn) gave rise to amorphous ZnO stabilized on nitrogen-doped carbon (ZnO–N/C) and was found to be innocent for H2 sensing, whereas the pyrolysis of bimetallic ZIF(Co–Zn) resulted in the formation of Co–ZnO–N/C nanostructure with a high dispersion of Co on amorphous ZnO. Co–ZnO–N/C inherited the nanostructure of the parent precursor with rhombododecahedron particles of 200–300 nm and possessed subnanometer pores. Co inclusion into ZnO has converted the innocent amorphous ZnO–N/C into a rapid room-temperature H2 sensor (by measuring the dynamic change in the resistance with respect to time). Co–ZnO–N/C displayed a 3.7% response % with 17–26 s of recovery–response times for 1% concentration of H2 under room-temperature conditions. The unique nanostructure of Co–ZnO–N/C enhanced the signal transduction (via N-doped carbon support) and promoted H2 diffusion (through subnanometer pores). Higher-temperature H2 sensing studies were also conducted at 200 °C, wherein Co–ZnO–N/C displayed an increase in response to 5.7% with 8–16 s of response–recovery times. Co–ZnO–N/C chemiresistor is a rare example that does not contain precious metals yet exhibits room-temperature hydrogen sensing.

Fluid flow-induced fine particle migration and its effects on gas and water production behavior from gas hydrate reservoir

Natural gas hydrates are widely distributed in silty marine sediments containing fine particles less than 75 μm in size. The effects of WC (water content) on the behavior of fine particle migration and their role in gas and water production do not appear well understood. This work found that the WC slightly affected the gas production pattern in uniform sandy reservoirs. Yet upon a mixture of coarse and fine particles, the fine particles would instantly aggregate at the nearby pore throat reducing the reservoir permeability and prolonging the production by more than 3 times. Surprisingly, 16% of the fine particles at the edge and 19% at the middle were found to migrate with the fluid flow upon increasing water content, resulting in a less hindered initial gas production but a following more complete blockage or even production failure. This behavior can be consolidated in the scenario of a sand-kaolin mixture. The findings could provide new knowledge on the particle migration behavior upon gas and especially water production and guide the strategy design on dealing with the sand problem in the field test.

Rotation induced by non-uniform gas–solid phase reactions of a non-spherical particle

• The particle rotation induced by gas–solid phase reactions is revealed; • The non-uniform gas–solid phase reaction directly results to the rotation of non-spherical particle; • The rotation characteristics of coal particle during combustion are discussed. Particle rotation plays an important role in gas–solid flow. The particle rotation induced by gas–solid phase reaction is investigated in this work. The non-uniform gas–solid phase reaction direct results to the rotation of a non-spherical particle. Based on the random distribution of active sites, the combustion of non-spherical particles is numerical investigated. According to the numerical results of chemical reaction rate on the particle surface, the net force and the rotation frequency of non-spherical particle were obtained by post-processing. The bearing force and rotation of cubic particles caused by gas–solid chemical reactions are systematically numerically studied. The rotational frequency is basically consistent with the experimental results in the reference. For coal char particles with an active area ratio of 0.8, the rotational frequency can reach 1000 Hz at side length of 60 μm. The effects of active area ratio, ambient gas temperature and particle size on the induced thrust and the rotational frequency of coal char particles are analyzed. The unbalanced force on the particle surface increase with the reaction rates. The rotation velocity increases with the decrease of particle size. And it increases with the increase of ambient temperature..

Investigations on RuO2–In2O3 nanostructured porous composite thin films for benzene detection

Oxygen vacancies, oxidation and chemisorbed oxygen quantities will play a significant role in gas sensing properties of metal oxide semiconductors. Therefore, a suitable and effective method to improve the chemisorbed oxygen on the material surface is well needed to enhance the gas sensing performance. In the present investigations, mesoporous In2O3 and RuO2–In2O3 nanocomposite porous structured thin films with different RuO2 concentrations are prepared using the spray pyrolysis technique with optimized deposition parameters. Addition of RuO2 into In2O3 increases the chemisorbed oxygen on the surface of thin films. The prepared nanocomposite thin films' structural information, micromorphology, specific surface area and porosity are characterized by XRD, FESEM, AFM, TEM, UV–vis spectrophotometry, photoluminescence, XPS and BET. The enhancement of high specific surface area and porosity of RuO2–In2O3 nanocomposite thin films is favourable to gas sensing properties. The In2O3, RuO2–In2O3 nanocomposite thin films possessed highly selective, excellent response and recovery characteristics, and low detection limit towards benzene at room temperature. Among all the samples, RuO2–In2O3 nanocomposite thin film with a concentration of 20 wt% of RuO2 has shown remarkable sensing properties towards 50 ppm of benzene at room temperature.

Characterization of WO3 thin films deposited by spray pyrolysis technique and its role in gas sensing

The work investigated in this paper focused on the fabrication of WO3 films by the spray pyrolysis technique, and different analyses were made to find optimized samples for studying properties suitable for the application of gas sensing. The substrate temperature is the most important parameter among other spray parameters for the synthesis of thin films hence WO3 thin films were deposited on glass substrates by maintaining the substrate temperature at 350 ºC, 450 ºC, 550 ºC, and 650 °C using compressed air as a carrier gas. The influence of the substrate temperature on the structural, morphological, compositional, and optical properties of the WO3 thin films has been justified using XRD data. Good and enhanced crystallinity is observed for the film deposited at a substrate temperature of 550 ºC. The nonconventional properties were studied by different investigations and confirmed by past research work. The manipulation of surface morphology with the different deposition temperatures is monitored. Only the characteristic peaks of W and O are present in the fabricated WO3 thin films. The optical activity of about 70 to 80 % of the selected sample in the visible region (300 to 1200 nm) is found. The selective absorption activity of light in the ultraviolet region and visible region is checked. The obtained IR bands confirmed the inter bridge stretching and bending modes of W-O and O-W-O. A high response towards ammonia compared to other test gases is exhibited. The repeatability of WO3 towards NH3 over three periodic sensing cycles, response, and recovery time has also been discussed. From all the characteristic studies, it has been suggested that the fabricated WO3 thin films have been used in the health care field to detect the toxic NH3 gas

Concurrent 3. Presentation for: The continuing role of gas as the natural companion to renewable energy

Presented on Tuesday 17 May: Session 3 Four years ago I gave a presentation entitled ‘Repositioning Gas in the Energy Mix’, where we outlined the need to continue to invest in natural gas in order to enable the penetration of renewable energy into the market. In that presentation we highlighted the danger of the ‘green, cheap squeeze’ on gas; squeezed by cleaner renewables on the one hand, and cheaper coal on the other, and proposed changing the messaging away from seeing gas as a transition fuel to acknowledging the longer-term enabling role gas would have to play in the energy mix. Since then several countries have managed to achieve significant reductions in emissions due to power generation, and we now have evidence that supports the continuing role of natural gas in the energy mix. This presentation will review the progress made in emissions’ reductions over the past few years, examining the key issues and confirming the impact that increasing amounts of renewable energy has on existing power generation and supply systems. We will also examine and provide insights into the issues requirements for further reductions in emission levels. To access the presentation click the link on the right. To read the full paper click here

Implementation of a Gas Leakage Detection System Using the MQ-6 Sensor

The role of gas at this time is very important for human life. The use of gas is expanding from household, industrial to transportation needs.Remember the depletion of petroleum supplies. This makes gas as an alternative fuel to replace the main role of petroleum. The risk of using gas as fuel is the occurrence of gas leaks which can have an impact on large-scale fires. A detection system is designed to detect gas leaks with the MQ-6 sensor and solenoid valve to close the gas line. The research was conducted by testing the voltage from the sensor using a predetermined program. The maximum reading distance from the gas sensor is 18 cm with a time of 45.26 seconds based on tests carried out by narrowing the gas exit path to provide a faster rate effect so that the sensor can detect gas.

The continuing role of gas as the natural companion to renewable energy

Four years ago I gave a presentation entitled ‘Repositioning Gas in the Energy Mix’, where we outlined the need to continue to invest in natural gas in order to enable the penetration of renewable energy into the market. In that presentation we highlighted the danger of the ‘green, cheap squeeze’ on gas; squeezed by cleaner renewables on the one hand, and cheaper coal on the other, and proposed changing the messaging away from seeing gas as a transition fuel to acknowledging the longer-term enabling role gas would have to play in the energy mix. Since then several countries have managed to achieve significant reductions in emissions due to power generation, and we now have evidence that supports the continuing role of natural gas in the energy mix. This presentation will review the progress made in emissions’ reductions over the past few years, examining the key issues and confirming the impact that increasing amounts of renewable energy has on existing power generation and supply systems. We will also examine and provide insights into the issues requirements for further reductions in emission levels.