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(a) Fact sheet of fires caused with flammable gases in USA and (b) Year wise fire deaths in USA, UK and India. Pie charts of fire causes in (a) USA and (b) India.
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An efficient room temperature sensor for liquified petroleum gas (LPG) is demonstrated employing CdS:SiO2 nanocomposite thin films (CdS:SiO2 NCTFs) for the first time. CdS:SiO2 NCTFs exhibiting morphology of CdS nanodroplets on micron sized spherical balls of SiO2 are deposited using pulsed laser deposition (PLD) method followed by thermal annealin...
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... far as India is concerned, the total number of accidental deaths by cooking gas cylinder/stove burst was 3525 during 2014 which was increased to 3,667 in 2015, according to the National Crime Records Bureau. More than 3 lakh deaths were reported due to fire related incidents with an average of 59 deaths per day between 2000 and 2016 in India [2]. Fig. 1 shows the fact sheets of fires caused by flammable gases in USA which infer that an average of 28% fire accidents in home and non-home structures are due to leakage of LPG only whereas 17% fire accidents are due to burst of cylinder/stoves in India as Pie chart in Fig.1b shows percentage of causes responsible for fires in India. The ...
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... than 3 lakh deaths were reported due to fire related incidents with an average of 59 deaths per day between 2000 and 2016 in India [2]. Fig. 1 shows the fact sheets of fires caused by flammable gases in USA which infer that an average of 28% fire accidents in home and non-home structures are due to leakage of LPG only whereas 17% fire accidents are due to burst of cylinder/stoves in India as Pie chart in Fig.1b shows percentage of causes responsible for fires in India. ...
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... that an average of 28% fire accidents in home and non-home structures are due to leakage of LPG only whereas 17% fire accidents are due to burst of cylinder/stoves in India as Pie chart in Fig.1b shows percentage of causes responsible for fires in India. The accident percentages of civilian deaths, injuries and property damages are depicted in Fig. 1a as a bar diagram. The statistics of fire death from 2000 to 2016 in USA, UK and India is shown in Fig.1b. Indeed the number of deaths in India is quite high with respect to developed countries like USA and UK however, these data looks comparable with respect to population of respective countries. For illustration; the fire death rate ...
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... accident percentages of civilian deaths, injuries and property damages are depicted in Fig. 1a as a bar diagram. The statistics of fire death from 2000 to 2016 in USA, UK and India is shown in Fig.1b. Indeed the number of deaths in India is quite high with respect to developed countries like USA and UK however, these data looks comparable with respect to population of respective countries. ...
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... with time. conduction band. This leads to an increased carrier concentration in the n-type semiconductor (nc-CdS) which results decrease in the resistance of the sensor S 0 , whereas the released electrons from the reaction recombine with the hole in p-type semiconductor (S 1, S 2 , and S 3 ) and turns to increase in the resistance [33,34] Fig. 10 shows the experimental representation of response and recovery time of S 2 . As the LPG injected into the chamber it starts to reacts on the surface of chemisorbed oxygen as illustrated by Fig.10a, which results transient in sensor's resistance. saturation state of sensor's resistance. When LPG extracted from chamber and fresh air ...
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... leads to an increased carrier concentration in the n-type semiconductor (nc-CdS) which results decrease in the resistance of the sensor S 0 , whereas the released electrons from the reaction recombine with the hole in p-type semiconductor (S 1, S 2 , and S 3 ) and turns to increase in the resistance [33,34] Fig. 10 shows the experimental representation of response and recovery time of S 2 . As the LPG injected into the chamber it starts to reacts on the surface of chemisorbed oxygen as illustrated by Fig.10a, which results transient in sensor's resistance. ...
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... state of sensor's resistance. When LPG extracted from chamber and fresh air injected into the chamber, removal of C n H 2n-2 and C n H 2n O -complexes along with water vapour takes place that is followed by chemisorption of oxygen on the sensor's surface (Fig.10c). Fig.10d corresponds to the gas sensing characteristic of S 2 . ...
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... LPG extracted from chamber and fresh air injected into the chamber, removal of C n H 2n-2 and C n H 2n O -complexes along with water vapour takes place that is followed by chemisorption of oxygen on the sensor's surface (Fig.10c). Fig.10d corresponds to the gas sensing characteristic of S 2 . ...
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... adsorption/desorption of gas molecules on the surface of sensor is responsible for change in resistance of the film. Here, the highest response is exhibited by sensor S 2 as compared to the others which can be explained as: the smooth surface and highly packed CdS nanoparticles construct nonporous surface and relatively large particle size reduces surface to volume ratio (See Fig.S1 and S3). As a fused effect S 0 offers less reactive sites for target gas which reflect in terms of response. ...
Citations
... When benzene comes in contact with these oxygen species, a greater no. of electrons moves from oxygen species towards benzene which reduces the potential barrier and thus decreases in depletion layer thickness occurs [36,37].This causes a rapid reduction in resistance of Au decorated WO 3 -SnO 2 nanocomposite Moreover, the addition of Au in WO 3 -SnO 2 nanocomposite results in increase in surface area of the nanocomposite. Further owing to catalytic activity of Au the catalytic dissociation of benzene enhances which further alter the potential barrier and depletion region [38,39]. The quantum confinement effect of Au in WO 3 -SnO 2 nanocomposite also contributes to increased response by enhancing the active sites on sensor. ...
In this present work, we synthesized WO3-SnO2 and Au decorated WO3-SnO2 nanocomposite by hydrothermal method. The optical characterization has been done by UV/Vis spectroscopy to determine the band gap (Eg) of pure and gold (Au) decorated WO3-SnO2 which shows a reduction in Eg value from 3.56 to 3.03 eV after addition of Au in WO3-SnO2 which improves the crystallinity of WO3-SnO2 . Fourier transformed Infra red (FTIR) spectroscopy has been used to confirm the chemical bonding between Au and WO3-SnO2 nanocomposite. The x-ray Diffraction (XRD) technique was used to study the structural aspects of prepared materials which shows the decrease in crystallite size from 8 to 6.7 nm after addition of Au in pure sample. Field Emission Scanning Electron Microscopy (FESEM) has been used to investigate morphological characteristics of as prepared nanocomposite. The doping of Au was further confirmed by Energy-Dispersive x-ray spectroscopy (EDS) technique. The sensing properties have been studied from the I–V measurement of WO3-SnO2/Au nanocomposite for Benzene. The sensing parameters such as sensitivity (response), operating temperature and response and recovery time were calculated for benzene vapors. The addition of Au in WO3-SnO2 increases its response to 2.7 times for 100 ppm benzene with a reduction in response/recovery time from 18/50 s to 13/29 s. The operating temperature was 300 °C. Further, the material is highly selective for benzene as compared to cyclohexane, toluene and aniline.
... Thus, the forward biased current of the nano-heterojunction improved, and (ii) interaction of lessening LPG molecules with the interface of the nano-heterojunction changed the work function of PbS, in the presence of LPG. In another study, pulsed laser deposited nanocrystalline CdS:SiO 2 thin films showed the maximum response of 0.71 for 1000 ppm at RT, which did not change when the temperature was increased to 75 but reduced to 35% at 100 [156]. The nanocomposite showed an excellent limit of detection (∼20 ppm). ...
Liquefied petroleum gas (LPG), which is mainly composed of hydrocarbons, such as propane and butane, is a flammable gas that is considered a clean source of energy. Currently, the overwhelming use of LPG as fuel in vehicles, domestic settings, and industry has led to several incidents and deaths globally due to leakage. As a result, the appropriate detection of LPG is vital; thus, gas-sensing devices that can monitor this gas rapidly and accurately at room temperature, are required. This work reviews the current advances in LPG gas sensors, which operate at room temperature. The influences of the synthesis methods and parameters, doping, and use of catalysts on the sensing performance are discussed. The formation of heterostructures made from semiconducting metal oxides, polymers, and graphene-based materials, which enhance the sensor selectivity and sensitivity, is also discussed. The future trends and challenges confronted in the advancement of LPG room temperature operational gas sensors, and critical ideas concerning the future evolution of LPG gas sensors, are deliberated. Additionally, the advancements in the next-generation gas sensors, such as the wireless detection of LPG leakage, self-powered sensors driven by triboelectric/piezoelectric mechanisms, and artificial intelligent systems are also reviewed. This review further focuses on the use of smartphones to circumvent the use of costly instruments and paves the way for cost-efficient and portable monitoring of LPG. Finally, the approach of utilizing the Internet of Things (IoT) to detect/monitor the leakage of LPG has also been discussed, which will provide better alerts to the users and thus minimize the effects of leakages.
... The long reaction time was due to the large surface area and the presence of nanopores, which required a long period to achieve equilibrium adsorption. This result was consistent with the AFM results presented in Table 1, which showed that the sample made with J= 30 mA/cm 2 presented the most observable porous structure [22,23]. ...
In this study, porous silicon (PSi) was used to manufacture gas sensors for acetone and ethanol. Samples of PSi were successfully prepared by photoelectrochemical etching and applied as an acetone and ethanol gas sensor at room temperature at various current densities J= 12, 24 and 30 mA/cm ² with an etching time of 10 min and hydrofluoric acid concentration of 40%. Well-ordered n-type PSi (100) was carefully studied for its chemical composition, surface structure and bond configuration of the surface via X-ray diffraction, atomic force microscopy, Fourier transform infrared spectroscopy and photoluminescence tests. Results showed that the best sensitivity of PSi was to acetone gas than to ethanol under the same conditions at an etching current density of 30 mA/cm ² , reaching about 2.413 at a concentration of 500 parts per million. The PSi layers served as low-cost and high-quality acetone gas sensors. Thus, PSi can be used to replace expensive materials used in gas sensors that function at low temperatures, including room temperature. The material has an exceptionally high surface-to-volume ratio (increasing surface area) and demonstrates ease of fabrication and compatibility with manufacturing processes of silicon microelectronics.
... Similarly, MCs have been utilized together with other inorganic materials for advanced sensors e.g. Saxena et al [286] demonstrated LPG (1000 ppm) detection using CdS/SiO 2 nanocomposites with response of ∼71% and LOD as 20 ppm. ...
We have faced the challenges from atmosphere environment due to the exposing toxic gases or liquids. Moreover, we also need to test some gases such as acetone, ethanol, and petroleum for our health or safety. Therefore, it is important to develop various gas sensors for testing them. Sensing materials play important roles in determining the performance of gas sensors. Thus, a great deal of work has been focused on the material studies. In this content, we need to discuss different materials as gas sensing materials systematically, and further give comments on the status at present and future challenges. This inspire us to assemble this 2020 Gas Sensing Materials Roadmap for discussing 29 gas sensing materials and their applications in different gas sensors by different experts.
... Many metal oxides, rare earth oxides (REO) have been used for LPG gas sensors [15][16][17][18]. Among them, cerium dioxide (CeO 2 ) also known as ceria belongs to rare earth (RE) family [19,20] and MgO is pre-transition metal oxide [21] are two technologically relevant materials with broad applications in various fields, like photo catalysis, gas sensors, energy storage devices [22][23][24][25][26]. ...
Nowadays, gas sensors are playing an essential role in wearable electronic devices for detecting pollutant, flammable, toxic gases besides it needs to be flexible, transparent, and operating at room temperature. Liquefied petroleum gas detection is critical because it is a flammable and toxic gas that of dangerous to humans as well the environment. The present study reports the hydrothermally synthesized MgO@CeO2 nanocomposite coated on flexible Polyethylene terephthalate substrate printed interdigitated gold electrodes (working electrodes) through the spin coating and continued for liquefied petroleum gas detection (50–900 ppm) at room temperature. X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and transmission electron microscopy were used to analyze the structural and morphological studies of prepared nanomaterials. The fabricated low-cost, eco-friendly MgO@CeO2 chemiresistive flexible sensor showed good selectivity towards analyte at room temperature with a sensitivity of 32% at 900 ppm and lower detection of 5% towards 50 ppm along with good long-term stability and mechanical flexibility.
A review of the state of research in the development of conductometric gas sensors based on II–VI semiconductors is given. It was shown that II–VI compounds indeed have properties that are necessary for the development of highly efficient gas sensors. In this case, to achieve the required parameters, all approaches developed for metal oxides can be used. At the same time, during a detailed review, it was concluded that sensors based on II–VI compounds have no prospects for appearing on the gas sensor market. The main obstacle is the instability of the surface state, which leads to poor reproducibility of parameters and drift of sensor characteristics during operation.
This chapter details the recent advances in the field of metal oxide (MO) nanocomposites for sensing gases and volatile organic compounds (VOCs) based on optical methods like luminescence and fluorescence other than fiber optics and surface plasmon resonance. Luminescent MO nanocomposite sensors are reusable, highly selective, sensitive, accurate, and fast. There is a huge demand for cost-effective optical MO nanocomposite-based optical sensors for the detection of gases and VOCs, particularly for acetic acid, H2S, propanol, LPG, TCE, etc. MO nanocomposites are highly useful in cataluminescence (CTL)-based sensing as they provide an oxygenated environment for CTL to occur. These CTL sensors provide high sensitivity, fast response, simple instrumentation, long-term stability, and environmental friendliness as well as low costs. Additionally, fluorescence-based ratiometric and colorimetric sensors based on MO nanocomposites are paving the way for indoor and outdoor wide-area pollution monitoring.
Microstructural defects play a critical role in flourishing various properties of materials. Here in this article, the effect of Ag substitution on the various properties of CdS quantum dots (QDs) is studied. Ag doped CdS QDs are synthesized using chemical co-precipitation, a simple, cost-effective method suitable for mass-production. High resolution transmission electron microscopy (HRTEM) images show dopant induced change in density and types of microstructural defects. The development of multiple nanotwinning at the cost of stacking faults as well as single twin boundary via the substitution of Ag in CdS lattice is noticed. In present study, a strong quantum confinement is observed and confirmed by the crystallite sizes estimated via X-ray diffraction (XRD) and TEM studies. A systematic enhancement in the bandgap and reduction in crystallite size are observed with increasing concentration of dopant. The atomic concentration of element and chemical bonding in CdS QDs are studied using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) respectively. Unlike other elemental dopants, QDs when doped with Ag with the varying concentration exhibit a non-systematic emission behaviour with increasing concentration which is correlated to the microstructural defects and confinement strength.
Semiconductor photocatalyst nanomaterials are being extensively studied for last a few decades due to their great potentials in solving energy and environmental problems on the earth by harnessing solar light....
