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C D Lokhande - One of the best experts on this subject based on the ideXlab platform.
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chemically deposited cubic structured cdo thin films use in liquefied petroleum Gas sensor
Sensors and Actuators B-chemical, 2014Co-Authors: R N Bulakhe, C D LokhandeAbstract:Abstract Cadmium oxide (CdO) thin films have been synthesized by chemical bath deposition (CBD) method. The deposition is carried out at room temperature (300 K). The surface morphology of the CdO thin films showed interconnected prism-like structure. The CdO thin films are oriented along (1 1 1) plane with the cubic crystal structure. The sensing properties of nanostructured CdO thin films have been studied for liquefied petroleum Gas (LPG) at operating temperature of 573 K. The CdO thin films exhibited maximum Gas Response of 44% upon the LPG exposure of 1040 ppm.
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morphology evolution of zno thin films from aqueous solutions and their application to liquefied petroleum Gas lpg sensor
Journal of Alloys and Compounds, 2012Co-Authors: K V Gurav, Seung Wook Shin, U M Patil, S M Pawar, Jin Hyeok Kim, C D LokhandeAbstract:Abstract The chemical bath deposition method is used to prepare two-dimensional flakes and one-dimensional rods of ZnO. By changing the bath temperature, ZnO morphology can be changed from flakes to rods. Further orientation of ZnO rods are selectively controlled by varying the content of H 2 O 2 in the bath solution. These films are structurally and morphologically characterized using X-ray diffraction and scanning electron microscopy respectively. The dependence of liquefied petroleum Gas (LPG) sensing properties on morphology and orientation of ZnO thin film are investigated. The vertically aligned ZnO rods exhibited the maximum Gas Response of 49% at 573 K upon exposure to 5200 ppm of LPG.
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effect of film thickness on liquefied petroleum Gas lpg sensing properties of silar deposited cdo thin films
Sensors and Actuators B-chemical, 2008Co-Authors: Rahul R Salunkhe, C D LokhandeAbstract:Abstract Nanocrystalline cadmium oxide (CdO) thin films of different thicknesses were deposited on a glass substrate by a simple chemical method (successive ionic layer adsorption and reaction, SILAR) based on alternate dipping of the substrate in an alkaline cadmium nitrate solution and double-distilled water containing 1% H 2 O 2 , followed by air heat treatment at 723 K for 5 h. The cadmium oxide thin films were used as sensing layers for liquefied petroleum (LPG) resistive Gas sensors. These samples were structurally and morphologically characterized using X-ray diffraction and SEM techniques, respectively. The dependence of LPG sensing properties on the thickness of CdO thin film was investigated. Maximum Gas Response achieved was 18.75% for the film of thickness 1.5 μm at a fixed Gas concentration of 0.08 vol% at 698 K.
K V Gurav - One of the best experts on this subject based on the ideXlab platform.
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cu2znsns4 czts based room temperature liquefied petroleum Gas lpg sensor
Sensors and Actuators B-chemical, 2014Co-Authors: K V Gurav, Seung Wook Shin, U M Patil, P R Deshmukh, M P Suryawanshi, G L Agawane, S M Pawar, P S PatilAbstract:Abstract In the present manuscript, we report for the first time Cu 2 ZnSnS 4 (CZTS)-based heterojunction (p-CZTS/n-ZnO) used for room temperature liquefied petroleum Gas (LPG) sensing. Specifically, the nanostructured ZnO has been grown chemically onto the sputtered CZTS thin films. The formations of phase pure CZTS and ZnO are confirmed by X-ray diffraction studies. The high quality heterojunction between compact CZTS and nanosized ZnO is obtained. At room temperature, the CZTS-based heterojunction exhibited Gas Response of 19.3% upon exposure to 1200 ppm of LPG with faster Response and recovery time of 70 and 40 s.
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morphology evolution of zno thin films from aqueous solutions and their application to liquefied petroleum Gas lpg sensor
Journal of Alloys and Compounds, 2012Co-Authors: K V Gurav, Seung Wook Shin, U M Patil, S M Pawar, Jin Hyeok Kim, C D LokhandeAbstract:Abstract The chemical bath deposition method is used to prepare two-dimensional flakes and one-dimensional rods of ZnO. By changing the bath temperature, ZnO morphology can be changed from flakes to rods. Further orientation of ZnO rods are selectively controlled by varying the content of H 2 O 2 in the bath solution. These films are structurally and morphologically characterized using X-ray diffraction and scanning electron microscopy respectively. The dependence of liquefied petroleum Gas (LPG) sensing properties on morphology and orientation of ZnO thin film are investigated. The vertically aligned ZnO rods exhibited the maximum Gas Response of 49% at 573 K upon exposure to 5200 ppm of LPG.
Oleg Lupan - One of the best experts on this subject based on the ideXlab platform.
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ultra sensitive and selective hydrogen nanosensor with fast Response at room temperature based on a single pd zno nanowire
Sensors and Actuators B-chemical, 2018Co-Authors: Oleg Lupan, Vasile Postica, Frederic Labat, Ilaria Ciofini, Thierry Pauporte, Rainer AdelungAbstract:Abstract In this work the Gas sensing properties of nanosensors fabricated by a “bottom-up” approach in a FIB/SEM system based on a single Pd modified ZnO nanowire is investigated in detail. Synthesis, surface doping and functionalization of ZnO nanowires (NWs) with Pd (Pd/ZnO) in a one − step process were performed during electrochemical deposition. The influence of the diameter of the NW, the operating temperature and the humidity are studied in detail and corresponding sensing mechanisms are proposed. An increase in the Gas Response by a decrease of the NW diameter was observed. Also, by increasing the operating temperature to 200 °C an enhancement in the hydrogen Gas Response of about 3.5 times (from ≈400 to 1440 to 100 ppm) was obtained and was attributed to the increased catalytic properties of the Pd nanoparticles (NPs). However, long-term investigations revealed a lowered signal stability of the nanosensor operated at higher temperatures. Thus, one can conclude that operation at room temperature is more efficient for real applications, due to the higher reliability of the nanodevices. The presented results demonstrate the importance of nanosensor applications and their high flexibility. The very low current values in the passive regime (in the range of pA − nA) and a very small dimension of the device results in an ultra-low power consumption, which is a key aspect for battery powered handheld instruments.
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individual hollow and mesoporous aero graphitic microtube based devices for Gas sensing applications
Applied Physics Letters, 2017Co-Authors: Oleg Lupan, Vasile Postica, Janik Marx, Matthias Mecklenburg, Yogendra Kumar Mishra, Karl Schulte, Bodo Fiedler, Rainer AdelungAbstract:In this work, individual hollow and mesoporous graphitic microtubes were integrated into electronic devices using a FIB/SEM system and were investigated as Gas and vapor sensors by applying different bias voltages (in the range of 10 mV–1 V). By increasing the bias voltage, a slight current enhancement is observed, which is mainly attributed to the self-heating effect. A different behavior of ammonia NH3 vapor sensing by increasing the applied bias voltage for hollow and mesoporous microtubes with diameters down to 300 nm is reported. In the case of the hollow microtube, an increase in the Response was observed, while a reverse effect has been noticed for the mesoporous microtube. It might be explained on the basis of the higher specific surface area (SSA) of the mesoporous microtube compared to the hollow one. Thus, at room temperature when the surface chemical reaction rate (k) prevails on the Gas diffusion rate (DK) the structures with a larger SSA possess a higher Response. By increasing the bias voltage, i.e., the overall temperature of the structure, DK becomes a limiting step in the Gas Response. Therefore, at higher bias voltages the larger pores will facilitate an enhanced Gas diffusion, i.e., a higher Gas Response. The present study demonstrates the importance of the material porosity towards Gas sensing applications.In this work, individual hollow and mesoporous graphitic microtubes were integrated into electronic devices using a FIB/SEM system and were investigated as Gas and vapor sensors by applying different bias voltages (in the range of 10 mV–1 V). By increasing the bias voltage, a slight current enhancement is observed, which is mainly attributed to the self-heating effect. A different behavior of ammonia NH3 vapor sensing by increasing the applied bias voltage for hollow and mesoporous microtubes with diameters down to 300 nm is reported. In the case of the hollow microtube, an increase in the Response was observed, while a reverse effect has been noticed for the mesoporous microtube. It might be explained on the basis of the higher specific surface area (SSA) of the mesoporous microtube compared to the hollow one. Thus, at room temperature when the surface chemical reaction rate (k) prevails on the Gas diffusion rate (DK) the structures with a larger SSA possess a higher Response. By increasing the bias volt...
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multifunctional materials a case study of the effects of metal doping on zno tetrapods with bismuth and tin oxides
Advanced Functional Materials, 2017Co-Authors: Vasile Postica, Oleg Lupan, Rainer Adelung, Jorit Grottrup, Abhishek Kumar Mishra, Nora H De Leeuw, N Ababii, J F C CarreiraAbstract:Hybrid metal oxide nano- and microstructures exhibit novel properties, which make them promising candidates for a wide range of applications, including Gas sensing. In this work, the characteristics of the hybrid ZnO-Bi2O3 and ZnO-Zn2SnO4 tetrapod (T) networks are investigated in detail. The Gas sensing studies reveal improved performance of the hybrid networks compared to pure ZnO-T networks. For the ZnO-T-Bi2O3 networks, an enhancement in H2 Gas Response is obtained, although the observed p-type sensing behavior is attributed to the formed junctions between the arms of ZnO-T covered with Bi2O3 and the modulation of the regions where holes accumulate under exposure to H2 Gas. In ZnO-T-Zn2SnO4 networks, a change in selectivity to CO Gas with high Response is noted. The devices based on individual ZnO-T-Bi2O3 and ZnO-T-Zn2SnO4 structures showed an enhanced H2 Gas Response, which is explained on the basis of interactions (electronic sensitization) between the ZnO-T arm and Bi2O3 shell layer and single Schottky contact structure, respectively. Density functional theory-based calculations provide mechanistic insights into the interaction of H2 and CO Gas molecules with Bi- and Sn-doped ZnO(0001) surfaces, revealing changes in the Fermi energies, as well as charge transfer between the molecules and surface species, which facilitate Gas sensing.
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highly sensitive and selective hydrogen single nanowire nanosensor
Sensors and Actuators B-chemical, 2012Co-Authors: Oleg Lupan, Thierry Pauporte, Lee Chow, Luis K Ono, Roldan B Cuenya, Guangyu ChaiAbstract:a b s t r a c t Metal oxides such as ZnO have been used as hydrogen sensors for a number of years. Through doping, the Gas Response of zinc oxide to hydrogen has been improved. Cadmium-doped ZnO nanowires (NWs) with high aspect ratio have been grown by electrodeposition. Single doped ZnO NWs have been iso- lated and contacted to form a nanodevice. Such nanosystem demonstrates an enhanced Gas Response and selectivity for the detection of hydrogen at room temperature compared to previously reported H2 nanosensors based on pure single-ZnO NWs or multiple NWs. A dependence of the Gas Response of a single Cd-ZnO nanowire on the NW diameter and Cd content was observed. It is shown that cadmium-doping in single-crystal zinc oxide NWs can be used to optimize their Response to Gases without the requirement of external heaters. The sensing mechanisms responsible for such improved Response to hydrogen are discussed.
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selective hydrogen Gas nanosensor using individual zno nanowire with fast Response at room temperature
Sensors and Actuators B-chemical, 2010Co-Authors: Oleg Lupan, Lee Chow, Guangyu Chai, V V Ursaki, G A Emelchenko, I M Tiginyanu, A N Gruzintsev, A N RedkinAbstract:In this work, we report on a single ZnO nanowire-based nanoscale sensor fabricated using focused ion beam (FIB/SEM) instrument. We studied the diameter dependence of the Gas Response and selectivity of ZnO nanowires (NWs) synthesized by chemical vapor phase growth method. The photoluminescence (PL) measurements were used to determine the deep levels related to defects which are presented in the ZnO nanomaterial as well as to evaluate the effect of thermal treatment in H2 atmosphere on the emission from ZnO nanowires. We show that sample annealed in hydrogen leads to passivation of recombination centers thus modifying the NWs properties. We studied the Gas Response and selectivity of these ZnO nanowires to H2 ,N H 3, i-Butane, CH4 Gases at room temperature. Our results indicated that zinc oxide NWs hold a high promise for nanoscale sensor applications due to its capability to operate at room-temperature and its ability to tune the Gas Response and selectivity by the defect concentration and the diameter of ZnO nanowire. A method is proposed to reduce the nanosensor’s recovery time through the irradiation with an ultraviolet radiation pulse. The sensing mechanisms of ZnO nanowires will be discussed.
P S Patil - One of the best experts on this subject based on the ideXlab platform.
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sensitivity enhancement of ammonia Gas sensor based on ag zno flower and nanoellipsoids at low temperature
Sensors and Actuators B-chemical, 2018Co-Authors: P S Patil, Sankar R Ganesh, M Navaneethan, V L Patil, S Ponnusamy, C Muthamizhchelvan, Shinji Kawasaki, Y HayakawaAbstract:Abstract High sensitivity ammonia Gas sensor based on Ag/ZnO composite (SZO) nanostructures and their structural, optical, morphological and Gas sensing properties were investigated. Field- emission scanning electron microscopy and high- resolution transmission electron microscopy revealed that pure ZnO flower-like nanorods transformed into nanoellipsoids upon adding of silver (Ag). Scanning transmission electron microscopy (STEM) analysis showed clear flower-like morphology of Ag/ZnO composite. STEM-mapping measurement showed that Zn, Ag and O were homogeneously distributed. The ammonia Gas sensing analysis revealed that the Ag/ZnO (6 wt%) showed higher Gas Response compared with other content of Ag wt%. Ag/ZnO (6 wt%) exhibited the highest Response of 29.5 when exposed to 100 ppm ammonia Gas. Interestingly, Ag/ZnO (6 wt%) possessed good Response and recovery property of 13 and 20 s at low concentration of ammonia at 10 ppm, respectively. The mechanism of Gas sensing and enhanced Gas Response of pure ZnO and Ag/ZnO composite was discussed.
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cu2znsns4 czts based room temperature liquefied petroleum Gas lpg sensor
Sensors and Actuators B-chemical, 2014Co-Authors: K V Gurav, Seung Wook Shin, U M Patil, P R Deshmukh, M P Suryawanshi, G L Agawane, S M Pawar, P S PatilAbstract:Abstract In the present manuscript, we report for the first time Cu 2 ZnSnS 4 (CZTS)-based heterojunction (p-CZTS/n-ZnO) used for room temperature liquefied petroleum Gas (LPG) sensing. Specifically, the nanostructured ZnO has been grown chemically onto the sputtered CZTS thin films. The formations of phase pure CZTS and ZnO are confirmed by X-ray diffraction studies. The high quality heterojunction between compact CZTS and nanosized ZnO is obtained. At room temperature, the CZTS-based heterojunction exhibited Gas Response of 19.3% upon exposure to 1200 ppm of LPG with faster Response and recovery time of 70 and 40 s.
Jong Heun Lee - One of the best experts on this subject based on the ideXlab platform.
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the role of nio doping in reducing the impact of humidity on the performance of sno2 based Gas sensors synthesis strategies and phenomenological and spectroscopic studies
Advanced Functional Materials, 2011Co-Authors: Hae Ryong Kim, Ildoo Kim, Alexander Haensch, Nicolae Barsan, U Weimar, Jong Heun LeeAbstract:The humidity dependence of the Gas-sensing characteristics in SnO2-based sensors, one of the greatest obstacles in Gas-sensor applications, is reduced to a negligible level by NiO doping. In a dry atmosphere, undoped hierarchical SnO2 nanostructures prepared by the self-assembly of crystalline nanosheets show a high CO Response and a rapid Response speed. However, the Gas Response, Response/recovery speeds, and resistance in air are deteriorated or changed significantly in a humid atmosphere. When hierarchical SnO2 nanostructures are doped with 0.64–1.27 wt% NiO, all of the Gas-sensing characteristics remain similar, even after changing the atmosphere from a dry to wet one. According to diffuse-reflectance Fourier transform IR measurements, it is found that the most of the water-driven species are predominantly absorbed not by the SnO2 but by the NiO, and thus the electrochemical interaction between the humidity and the SnO2 sensor surface is totally blocked. NiO-doped hierarchical SnO2 sensors exhibit an exceptionally fast Response speed (1.6 s), a fast recovery speed (2.8 s) and a superior Gas Response (Ra/Rg = 2.8 at 50 ppm CO (Ra: resistance in air, Rg: resistance in Gas)) even in a 25% r.h. atmosphere. The doping of hierarchical SnO2 nanostructures with NiO is a very-promising approach to reduce the dependence of the Gas-sensing characteristics on humidity without sacrificing the high Gas Response, the ultrafast Response and the ultrafast recovery.
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facile control of c2h5oh sensing characteristics by decorating discrete ag nanoclusters on sno2 nanowire networks
ACS Applied Materials & Interfaces, 2011Co-Authors: In Sung Hwang, Sun Jung Kim, Joong Ki Choi, Hyung Sik Woo, Se Yeon Jung, Tae Yeon Seong, Ildoo Kim, Jong Heun LeeAbstract:The effect of Ag decoration on the Gas sensing characteristics of SnO2 nanowire (NW) networks was investigated. The Ag layers with thicknesses of 5–50 nm were uniformly coated on the surface of SnO2 NWs via e-beam evaporation, which were converted into isolated or continuous configurations of Ag islands by heat treatment at 450 °C for 2 h. The SnO2 NWs decorated by isolated Ag nano-islands displayed a 3.7-fold enhancement in Gas Response to 100 ppm C2H5OH at 450 °C compared to pristine SnO2 NWs. In contrast, as the Ag decoration layers became continuous, the Response to C2H5OH decreased significantly. The enhancement and deterioration of the C2H5OH sensing characteristics by the introduction of the Ag decoration layer were strongly governed by the morphological configurations of the Ag catalysts on SnO2 NWs and their sensitization mechanism.
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synthesis and Gas sensing characteristics of highly crystalline zno sno2 core shell nanowires
Sensors and Actuators B-chemical, 2010Co-Authors: In Sung Hwang, Sun Jung Kim, Joong Ki Choi, Jaewan Choi, Gyutae Kim, Guozhong Cao, Jong Heun LeeAbstract:Abstract The ZnO–SnO2 core–shell nanowires (NWs) were synthesized by a continuous two-step vapor growth method at different synthesis temperatures. A crystalline 15–20 nm-thick, SnO2 shell layer was pseudo-epitaxially coated on ZnO NWs with a diameter of 50–80 nm. The Gas Response of the ZnO–SnO2 core–shell NW sensor to 10 ppm NO2 reached ∼33 times enhancement compared to that of the ZnO NWs at 200 °C. In addition, the ZnO–SnO2 core–shell NW sensors showed selective detection to NO2 at 200–300 °C and to C2H5OH at 400 °C. The enhanced Gas Responses to NO2 and C2H5OH are discussed in relation to the thin SnO2 shell layer and core–shell configuration of the NWs.
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Gas sensors using hierarchical and hollow oxide nanostructures overview
Sensors and Actuators B-chemical, 2009Co-Authors: Jong Heun LeeAbstract:Hierarchical and hollow oxide nanostructures are very promising Gas sensor materials due to their high surface area and well-aligned nanoporous structures with a less agglomerated configurations. Various synthetic strategies to prepare such hierarchical and hollow structures for Gas sensor applications are reviewed and the principle parameters and mechanisms to enhance the Gas sensing characteristics are investigated. The literature data clearly show that hierarchical and hollow nanostructures increase both the Gas Response and Response speed simultaneously and substantially. This can be explained by the rapid and effective Gas diffusion toward the entire sensing surfaces via the porous structures. Finally, the impact of highly sensitive and fast responding Gas sensors using hierarchical and hollow nanostructures on future research directions is discussed.
