Solid-state titania-based gas sensor for liquefied petroleum gas detection at room temperature

This paper reports the liquefied petroleum gas (LPG) sensing of titanium dioxide (Qualigens, India). Scanning electron micrographs and X-ray diffraction studies of samples were done. SEM shows that the material is porous and has grapes-like morphology before exposure to the LPG. XRD patterns reveal the crystalline nature of the material. The crystallites sizes of the TiO₂ were found in the range of 30–75 nm. Variations in resistance with exposure of LPG to the sensing element were observed. The average sensitivity for different volume percentages of gas was estimated. The maximum value of average sensitivity was 1·7 for higher vol.% of LPG. Percentage sensor response (%SR) as a function of time was calculated and its maximum value was 45%. Response time of the sensor was 70 s. The sensor was quite sensitive to LPG and results were found reproducible.     

Preparation and characterization of barium stannate: application as a liquefied petroleum gas sensor†

Barium stannate, BaSnO₃, an n-type semiconducting oxide with cubic perovskite structure, has been prepared by the thermal decomposition of barium carbonate (BaCO₃) and tin tetrahydroxide (Sn(OH)₄). The material was characterized by various physical techniques such as differential thermal analysis (DTA/TG), X-ray diffraction (XRD), BET surface area, Fourier transform infra-red (FT-IR) spectroscopy and scanning electron microscopy (SEM). Of its several applications, this material has proven to be one of the successful candidates for the detection of liquefied petroleum gas (LPG). The sensor has a very good selectivity to detect LPG in comparison to other reducing gases, like carbon monoxide and methane.     

Nanostructured ZnFe2O4 thick film as room temperature liquefied petroleum gas sensor

In the present work, thick film of nanostructured zinc ferrite was prepared by screen printing method and its liquefied petroleum gas (LPG) sensing properties were investigated. The structural and surface morphological characterisations of the sample were analysed by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The minimum crystallite size of ZnFe₂O₄ calculated from Scherrer's formula is found to be 4 nm. SEM images exhibit the porous nature of the sensing material with a number of active sites. Optical characterisation of the film was carried out by ultraviolet–visible spectrophotometer. The estimated value of band gap of the film was found 1.91 eV. The LPG sensing properties of the zinc ferrite film were investigated at room temperature for different vol.% of LPG. The variations in electrical resistance of the film were measured with the exposure of LPG as a function of time. The maximum values of sensitivity and percentage sensor response were found 16 and 1785, respectively, for 5 vol.% of LPG. These experimental results show that nanostructured zinc ferrite is a promising material for LPG sensor.     

High-performance gas sensor based on GO/In2O3 nanocomposite for ethanol detection

Journal of Materials Science: Materials in Electronics - Gas sensors are widely used because of their high sensitivity, low cost and simple fabrication. The development of high-performance ethanol...     

High-performance flexible self-powered strain sensor based on carbon nanotube/ZnSe/CoSe2 nanocomposite film electrodes

High-performance energy storage and sensing devices have been undergoing rapid development to meet the demand for portable and wearable electronic products,which require flexibility,extensibility,small volume and lightweight.In this study,we construct a lightweight and flexible self-powered sensing system by integrating a highly stretchable strain sensor with a high-performance asymmetric supercapacitor based on ZnSe/CoSe₂//ECNT(ECNT:electrochemically activated carbon nanotube film).The ZnSe/CoSe₂ two-dimentional nanosheets on carbon nanotube(CNT)films are synthesized through a simple and efficient strategy derived from ZnCo-based metal-organic frameworks(MOFs).The density functional theory(DFT)simulations show the higher conductivity of the ZnSe/CoSe₂/CNT electrode than the CoSe₂/CNT electrode.Due to the synergistic properties of self-supported two-dimentional ZnSe/CoSe₂ nanosheets with high specific surface area and the high pathway of one-dimention CNTs,the nanocomposite electrode provides efficient transmission and short paths for electron/ion diffusion.The asymmetric supercapacitor provides a stable output power supply to the sensors that can precisely respond to strain and pressure changes.The sensor can also be attached to a garment for measuring a variety of joint movements.     

液化石油气中二甲醚及各烃类组分气相色谱法研究

建立一套气相色谱检测方法,分析条件如下:不锈钢色谱柱(6 m×3 mm);固定液为邻苯二甲酸二壬酯和β-β′-氧二丙腈的混合物,混合比例为1∶1,涂布浓度为20%,载体为6201红色担体,载体颗粒的粒径为1.65~1.98 mm;载气为氢气,流量40m L/min,柱温35℃,气化温度100℃,热导池检测器温度110℃。检测方法的相对标准偏差在0.39%~2.78%之间,加标回收率在94.1%~104.3%之间,操作简洁、分析快速、结果准确。     

Sensing behaviour of nanosized zinc-tin composite oxide towards liquefied petroleum gas and ethanol

A chemical route has been used to synthesize composite oxides of zinc and tin. An ammonia solution was added to equal amounts of zinc and tin chloride solutions of same molarities to obtain precipitates. Three portions of these precipitates were annealed at 400, 600 and 800 °C, respectively. Results of X-ray diffraction and transmission electron microscopy clearly depicted coexistence of phases of nano-sized SnO₂, ZnO, Zn₂SnO₄ and ZnSnO₃. The effect of annealing on structure, morphology and sensing has been observed as well. It has been observed that annealing promoted growth of Zn₂SnO₄ and ZnSnO₃ at the expense of zinc. The sensing response of fabricated sensors from these materials to 250 ppm LPG and ethanol has been investigated. The sensor fabricated from powder annealed at 400 °C responded better to LPG than ethanol.     

基于Modelica的生物质燃气内燃机性能模拟研究

针对由沼气成分及其理化特性导致的内燃机燃用沼气时会发生燃烧速度慢、后燃严重、排气温度高等问题,将生物质燃气内燃机作为研究对象,基于可重用性及面向对象的Modelica语言建立内燃机模型库,将生物质燃气为燃料对四缸四冲程火花点火内燃机性能进行分析.通过仿真研究不同比例天然气(体积分数分别为33%,67%及100%)和LP...     

Effect of graphene concentration on performance of MEH:PPV/graphene nanocomposite based devices

Herein, we explore the effect of graphene concentration on performance of poly [2-methoxy-5-2-ethylhexoxy-p-phenylene vinylene] (MEH:PPV)/graphene nanocomposite based devices. The surface morphology of the nanocomposites analyzed through emission scanning electron microscopy suggest that increase in graphene concentration results in the formation of aggregation. Optical and structural properties of the nanocomposites examined through UV–Vis absorption and Raman spectra revealed that the addition of graphene has no affect on the conjugation length and structure of the MEH:PPV. The electrical characteristics of devices have been investigated by I–V measurement under dark and illumination at room temperature. The devices show increase in the current value and reduction on turn-on voltage with increase in the graphene concentration up to 5 wt%. However, increase in graphene concentration above 5 wt% leads to the performance degradation of the devices. Moreover, charge transport mechanisms of the devices have been explained through Ohmic behavior at lower voltages and trap charge limited conduction at higher voltages.     

Highly flexible and sensitive wearable strain and pressure sensor based on porous graphene paper for human motion

The demand for high-performance multifunctional wearable devices drives the rapid development of sensors with flexibility, sensitivity and easy preparation. Here, we report an efficient preparation method to fabricate a wearable strain and pressure sensor based on porous graphene paper (PGP), which is prepared by polymethylmethacrylate (PMMA) microsphere as a template. The prepared PGP-based strain and pressure sensor can detect multi-dimensional deformation and shows good flexibility even after more than 1000 s of repeated deformation cycles, while the rapid response time can be up to approximately 60 ms. Moreover, the obtained PGP-based sensor exhibits a good sensitivity that the gauge factor (GF) is up to 77 when the strain is in the range of 4–8%, much higher than other graphene materials. Importantly, the porous microstructure created by the PMMA microsphere in the PGP plays a vital role in the good comprehensive performance of the PGP-based sensor. The device shows potential applications in smart wearable devices to detect or monitor the posture and movement information of human beings.

     

Silicon doped SnO2 films for liquid petroleum gas sensor

Silicon doped SnO₂ films were synthesized by sputtering SnO₂ layer onto glass substrates with appropriate amount of silicon sputtered onto them. The bilayer structures were subjected to rapid thermal annealing for the incorporation of Si in SnO₂ matrix. The films thus obtained were characterized by measuring optical and microstructural properties. Liquid petroleum gas (LPG) sensing properties were also investigated. FTIR and Raman studies were also carried out on these films, both, before and after LPG exposure.     

In situ synthesis of silver/chemically reduced graphene nanocomposite and its use for low temperature conductive paste

In this work, we succeeded in the synthesis of Ag/chemically reduced graphene (Ag/G) nanocomposite by a facile in situ one-pot solvothermal route. X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectra and Fourier transform infrared spectroscopy results revealed the formation of Ag and the reduction of graphite oxide to graphene during the one-pot process. Scanning electron microscopy observation indicated that spherical Ag particles with a size less than 100 nm are wrapped by graphene. The Ag/G nanocomposite was used in a low temperature conductive paste. Thermal analysis was conducted to determine the proper curing process of the Ag/G conductive paste. The Ag/G conductive paste that contains 0.6 wt% graphene exhibits low sheet resistance (22 mΩ/sq/25 µm) and good stability after cured at 150?°C for 30 min, which made us believe that the Ag/G nanocomposite is a promising candidate for conductive paste.     

计算机技术在液化石油气密度和蒸汽压分析中的应用

本文介绍了液化石油气样品按SH/T0230—1992《液化石油气组成测定在(色谱法)》标准测定组成后(?)据GB/12576—1997《液化石油气蒸汽压和相对密度及辛烷值计算法》标准的算法,利用计算机技术对所测得液石油气的组成进行转换计算,继而快速准确计算出液化石油气的密度和蒸汽压。     

Fabrication of resistive CO gas sensor based on SnO2 nanopowders via low frequency AC electrophoretic deposition

A resistive CO gas sensor has been fabricated using AC electrophoretic deposition (ACEPD) technique. SnO₂ thick films are deposited by applying low frequency (0.01–1,000 Hz) AC electric field to a stable suspension of SnO₂ nanoparticles in acetyl acetone. A carbon film base electrode is used as deposit substrate. Effect of CO gas exposure on conductivity of the SnO₂ film at 300 °C is investigated. Results show that the sensor is sensitive and its response is repeatable. This work shows that ACEPD can be used as an easy and cheap technique for fabrication of electronic devices such as ceramic gas sensors.     

Surfactant assisted solid-state synthesis and gas sensor application of a SWCNT/SnO2 nanocomposite material

Although tin oxide has been the most widely investigated metal oxide material for gas detection, it suffers from the large resistance and high operating temperature. This could be overcome by hybridization with nanostructured carbon. In this work, tin oxide nanoparticles with ultrasmall sizes of 1-3 nm have been uniformly coated onto bundles of single-walled carbon nanotubes by a surfactant assisted solid state synthesis approach for the first time. Gas sensor properties of the as-synthesized nanocomposite material toward NO2 (from 5 to 60 ppm) are measured at 150 degrees C. Compared to the pure carbon tubes gas sensors, the nanocomposite gas sensor responds to NO2 in low concentrations with good linearity, high sensitivity, and fast recovery, while working at a relatively low temperature.     

Liquid petroleum gas sensor based on SnO2/Pd composite films deposited on Si/SiO2 substrates

SnO₂/Pd composite films were synthesized by d.c. sputtering of a SnO₂ target followed by thermal evaporation of a thin layer of Pd on top of it. This structure, deposited on Si wafer with 300 μm SiO₂ on the top, was subjected to rapid thermal annealing at 573 K for 5 min for the incorporation of Pd in SnO₂. The films were characterized by microstructural, optical, FTIR and Raman studies. Liquid petroleum gas (LPG) sensing measurements were carried out on these films. Sensitivity of 72% was obtained at an operating temperature of ∼573 K. The response time for these sensors was found to be ∼27 s. Sensitivity was found to increase with grain growth at higher sensing temperatures. It could be observed that the selectivity for LPG is extremely good as compared to that of methane, hydrogen, CO₂ and C₂H₅OH.     

Highly conductive supercapacitor based on laser-induced graphene and silver nanowires

One of the foremost necessary desires of energy systems has been the existence of efficient, flexible, transportable, and eco-friendly devices. Among all the energy storage systems, supercapacitors have attracted plenty of attention thanks to their distinctive properties. Among all capacitor technologies, laser-induced graphene (LIG)-based capacitors are within the spotlight nowadays due to their high flexibility and simple manufacture. The most downside with LIG-based capacitors is their low conductivity and low charge capacity. During this work, to overcome this problem, the surface of LIG is covered with silver nanowires (AgNWs) and LIG/AgNWs composite is employed to form supercapacitor. In this study, all the electrochemical properties of the prepared composite were investigated, and therefore the results showed that AgNWs could increase the electrical conductivity of LIG by about 2.25 times, improve electrode–electrolyte interaction, and increase areal capacitance by 1.3 times. Additionally, the synthesized supercapacitor shows stable cyclic behavior and retention capacity equal to 78% after 1000 charge–discharge cycles. A singular increase in LIG conductivity and improved in its cyclic performance. Furthermore, galvanostatic charge/discharge curves indicated acceptable charge capacity of the LIG/AgNWs supercapacitor.

     

基于双向拉伸制备还原氧化石墨烯-碳纳米管复合薄膜的高性能柔性压阻传感器

随着现代科技的快速发展及人们生活水平的提高,柔性压阻传感器在人体健康监测、智能机器人、可穿戴电子设备和人机交互等方面展现了巨大应用潜力.本文采用Hummer's法制备了还原氧化石墨烯(rGO),其后通过静电组装将碳纳米管(CNT)负载在rGO的表面上,并将其引入热塑性聚氨酯(TPU)基体中制备成导电纳米复合材料.此外,...