Search query: Semiconductor, NO2,gas sensor

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abstract: Prolonged exposure to NO2 can cause lung tissue inflammation, bronchiolitis fibrosa obliterans, and silo filler's disease. In recent years, nanostructured semiconducting metal oxides have been widely used to fabricate gas sensors because of their unique structure and surface to volume ratio compared to layered materials. In particular, the different morphologies of ZnO based nanostructures significantly affect the detection property of NO2 gas sensors. However, because of the large interaction energy of chemisorption (1 10 eV) metal oxide based gas sensors are typically operated above 100 degC, overcoming the energy limits to attain high sensitivity and fast reaction. High operating temperature negatively affects the reliability and durability of semiconductor based sensors; at high temperature, the diffusion and sintering effects at the metal oxide grain boundaries are major factors causing undesirable long term drift problems and preventing stability improvements. Therefore, we demonstrate NO2 gas sensors consisting of ZnO hemitubes (HTs) and nanotubes (NTs) covered with TiO2 nanoparticles (NPs) To operate the gas sensor at room temperature (RT) we measured the gas sensing properties with ultraviolet illumination onto the active region of the gas sensor for photoactivation instead of conventional thermal activation by heating. The performance of these gas sensors was enhanced by the change of barrier potential at the ZnO/TiO2 interfaces, and their depletion layer was expanded by the NPs formation. The gas sensor based on ZnO HTs showed 1.2 times higher detection property than those consisting of ZnO NTs at the 25 ppm NO2 gas.
author_names: Hee-Jung Choi

Soon-Hwan Kwon

Wonseok Lee

Kwang-Gyun Im

Tae-Hyun Kim

Beom-Rae Noh

Sunghoon Park

Semi Oh

Kyoung-Kok Kim
title: Ultraviolet Photoactivated Room Temperature NO2 Gas Sensor of ZnO Hemitubes and Nanotubes Covered with TiO2 Nanoparticles
venue: Nanomaterials
year: 2020

abstract: Abstract Gas sensors based on a chemiresistive metal oxide semiconductor are widely used including nitrogen dioxide (NO 2 at a moderate temperature. In this work efforts are taken to fabricate NO 2 gas sensor using thin films of tungsten oxide (WO 3 grown directly on to a soda lime glass substrate without assistance of any seed layer by a simple and a facile hydrothermal technique. As per our knowledge, the deposition of nanostructured WO 3 thin films without assistance of any seed layer on the glass substrate was rarely reported. The WO 3 thin film samples were synthesized at various deposition times ranging from 3 h to 7 h and were characterized by X ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, UV vis spectroscopy and Brunauer Emmett Teller techniques. The surface morphological and structural characterization showed the two dimensional (2D) nanoplate like structure of as synthesized WO 3 thin films with plate thickness ranging from 90 to 150 nm and had an orthorhombic structure, respectively. Moreover, the 2D nanoplates of WO 3 exhibited a gas response ~10 for 5 ppm for toxic NO 2 gas at relatively low operating temperature. The new synthesis route and sensing behavior of as synthesized WO 3 nanoplates revealed a promising candidate for the fabrication of the cost effective gas sensors.
author_names: Suresh Shamrao Shendage

Vithoba L Patil

Sharadrao A Vanalakar

Sandip P Patil

Namdev S Harale

J L Bhosale

Jung Ha Kim

Pramod S Patil
title: Sensitive and selective NO2 gas sensor based on WO3 nanoplates
year: 2017

abstract: Single walled carbon nanotubes (SWNTs) are incorporated in different device configurations such as chemiresistors and field effect transistors (FETs) as a sensing element for the fabrication of highly sensitive and specific biochemical sensors. For this purpose, sorting and aligning of semiconducting SWNTs between the electrodes is advantageous. In this work, silicon shadow mask, fabricated using conventional semiconductor processes and silicon bulk micromachining were used to make metal contacts over SWNTs with a minimum feature of 1 um gap between the electrodes. The developed silicon shadow mask based metal contacts patterning process is cost effective, free from photoresist (PR) chemical coatings and thermal processing. After the detailed investigation, sodium dodecyl sulphate (SDS) an anionic surfactant along with ultrasonication process was found effective for the removal of unclamped and metallic SWNTs, resulting in aligned and clamped semiconducting SWNTs between the electrodes. The presence of aligned semiconducting SWNTs was confirmed using atomic force microscopy (AFM) field emission scanning electron microscopy (FESEM) and Raman spectroscopy techniques. The fabricated devices were tested for nitrogen dioxide (NO2) gas sensing as a test case. The sensitivity enhancement of ~21% to 76% in the 20 80 ppm NO2 concentration range has been observed in the case of aligned semiconducting SWNTs devices as compared to the random network SWNT based sensors.
author_names: Pankaj B Agarwal

Rishi Sharma

Dharmesh Mishra

Navneet Kumar Thakur

Ajay Agarwal

Ayyappanpillai Ajayaghosh
title: Silicon Shadow Mask Technology for Aligning and In Situ Sorting of Semiconducting SWNTs for Sensitivity Enhancement: A Case Study of NO2 Gas Sensor.
venue: ACS applied materials interfaces
year: 2020

abstract: Abstract The porous flake like Co3O4 and Co3O4/graphene hybrids with different graphene contents were prepared through a facile two step method. The field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) characterizations proved the tight adherence of graphene sheets to the surface of porous Co3O4 slices. Gas sensors based on the as synthesized products were then fabricated to explore their potential applications. The results indicated that the optimal hybrid exhibited a response of 26.8% to 5 ppm of NO2 at room temperature (RT) which was 2.27 times higher than that of undoped Co3O4 (100 degC) The hybrid sensor also showed fast response, excellent selectivity, long term stability and extremely low detection limit toward NO2 at RT. The significantly enhanced sensing properties to NO2 could be attributed to larger specific surface area, more chemisorbed oxygen species and the coupling effect between Co3O4 and graphene in the hybrid. As we all know, as a typical p type semiconductor, the gas sensing properties of Co3O4 toward oxidizing gases including NO2 was rarely reported. We believe that our work could pave the way for the future design of Co3O4 based gas sensors for oxidizing gases detection at low or even room temperature.
author_names: Bo Zhang

Ming Cheng

Guannan Liu

Yuan Gao

Lianjing Zhao

Shanshan Li

Yipei Wang

Fangmeng Liu

Xishuang Liang

Tong Zhang

Geyu Lu
title: Room temperature NO2 gas sensor based on porous Co3O4 slices/reduced graphene oxide hybrid
year: 2018

abstract: We report the development of a new type of organic semiconductor gas sensor based on a porphyrin based hydrogen bonded organic framework (HOF) Owing to the orderly porous structures, the decoration with rich amino sites and the n type semiconductor nature, this HOF based sensor exhibits selective NO2 sensing performance with ultra fast response/recovery rates (17.6 s/15.4 s over 100 ppb) and a limit of detection lower than 40 ppb, together with high sensitivity, good reproducibility, and long term stability at room temperature. This study demonstrates that HOF based materials have potential application prospects in gas sensing, thereby offering a new way of thinking for the design and development of sensors.
author_names: Yi-jie Wang

Di Liu

Jianbo Yin

Yanxue Shang

Juan Du

Zixi Kang

Rongming Wang

Yanli Chen

Daofeng Sun

Jianzhuang Jiang
title: An ultrafast responsive NO2 gas sensor based on a hydrogen bonded organic framework material.
venue: Chemical communications
year: 2019

abstract: Abstract ZIF 67 derived from crystalline Co3O4 coupled with g C3N4 nanosheets (NSs) was prepared and adopted for detecting ppb level NO2 gas at room temperature (RT) As obtained Co3O4 particles reside in the rhombohedral and porous framework structure inheriting from ZIF 67, which contact intimately with two dimensional g C3N4 nanosheets, leading to the formation of the p n heterojunction. This structure has maintained the benefits from ZIF 67, such as high surface area and greater porosity. Moreover, the introduction of n type semiconductor g C3N4 NSs has enhanced the local electron density of Co3O4 that can help in the fast transportation of charge carriers and resultantly increase the gas sensing properties. The optimal Co3O4/g C3N4 presents impressive response of 17.83 to 60 ppm to NO2 gas at room temperature, with fast response time (1.06 s) quick recovery time (26.6 s) long term stability and high selectivity. This approach offers new ideas to produce heterostructure between the metal organic frameworks derived metal oxides with g C3N4 NSs resultantly increases the sensitivity of metal oxides based gas sensors, which can be used as highly potential gas sensors.
author_names: Mohib Ullah

Xue Bai

Junkun Chen

He Lv

Zhuo Liu

Jue Wang

Baihe Sun

Luming Li

Keying Shi
title: Metal organic framework material derived Co3O4 coupled with graphitic carbon nitride as highly sensitive NO2 gas sensor at room temperature
year: 2020

abstract: Abstract Solution processed organic field effect transistor (OFET) has great potential in detecting various hazardous gases including nitrogen dioxide (NO2) To overcome the bottleneck of weak gas adsorption/interaction capability in single semiconductor sensing layer, semiconductor composites are used to enhance the sensing response. Here, we report an OFET based NO2 sensor whose active layer consists of diluted poly(3 hexylthiophene 2,5 diyl) (P3HT) with poly[N,N' bis(4 butylphenyl) N,N' bis(phenyl)benzidine] (poly TPD) Due to the site increase effect induced by phase segregation, the 90% diluted device possesses a more than 3 fold enhancement of current responsivity. Furthermore, when the gate voltage is switched from 40 V to 0 V, this device embodies 4.6 fold and 43.6 fold improvements at 0.3 ppm and 30 ppm, respectively. Meanwhile, decent selectivity, environmental stability and an excellent limit of detection of 242.6 ppb are realized.
author_names: Zuchong Yang

Xinming Zhuang

Shijiao Han

Junsheng Yu
title: Hole transporting polymer dilution driven high performance organic transistor based NO2 gas sensor
venue: Materials Letters
year: 2019

abstract: Abstract By using 1D ZnO nanorod, obtained from a simple two step chemical method as the sensor material, we report the fabrication of highly selective metal semiconductor metal (MSM) ultraviolet (UV) photodetector and NO2 gas sensor. The fabricated MSM UV photodetector and gas sensor possesses simplicity in material synthesis and sensor design. The effect of morphological evolution and structural intactness on the sensing properties of UV photodetector and NO2 gas sensor are deeply studied. The well aligned 1 dimensional (1D) ZnO nanorod provides high surface area for the sensing mechanism. The UV photodetector possesses high responsivity in the UV A region (364.81 A/W) with fast photoswitching characteristics at 5 V bias. It shows formation of good ohmic contact between metal semiconductor junctions. NO2 sensing measurement was carried out at relatively lower temperature of about 175 degC. The ZnO nanorods are highly selectivity towards NO2 gas and maximum gas response observed is 35 at 40 ppm of NO2. The NO2 gas sensor shows good repeatability at lower gas concentration of 2 ppm. The present synthesis technique provides cost effective route for obtaining highly ordered ZnO nanorods with simple sensor technology for multifunctional ZnO nanorod sensor.
author_names: Sohel Khalil Shaikh

V V Ganbavale

S V Mohite

Umakant M Patil

K Y Rajpure
title: ZnO nanorod based highly selective visible blind ultra violet photodetector and highly sensitive NO2 gas sensor
year: 2018

abstract: Because the oxides of nitrogen (NOx) cause detrimental effects on not only the environment but humans, developing a high performance NO2 gas sensor is a crucial issue for real time monitoring. To this end, metal oxide semiconductors have been employed for sensor materials. Because in general, semiconductor type gas sensors require a high working temperature, photoactivation has emerged as an alternative method for realizing the sensor working at room temperature. In this regard, titanium dioxide (TiO2) is a promising material for its photocatalytic ability with ultraviolet (UV) photonic energy. However, TiO2 based sensors inevitably encounter a problem of recombination of photogenerated electron hole pairs, which occurs in a short time. To address this challenge, in this study, TiO2 nanorods (NRs) and Pt nanoparticles (NPs) under a UV LED were used as an NO2 gas sensor to utilize the Schottky barrier formed at the TiO2 Pt junction, thereby capturing the photoactivated electrons by Pt NPs. The separation between the electron hole pairs might be further enhanced by plasmonic effects. In addition, it is reported that annealing TiO2 NRs can achieve noteworthy improvements in sensing performance. Elucidation of the performance enhancement is suggested with the investigation of the X ray diffraction patterns, which implies that the crystallinity was improved by the annealing process.
author_names: Jinhong Noh

Soon-Hwan Kwon

Sunghoon Park

Kyoung-Kok Kim

Yong-Jin Yoon
title: TiO2 Nanorods and Pt Nanoparticles under a UV LED for an NO2 Gas Sensor at Room Temperature
venue: Sensors
year: 2021

abstract: Abstract Cu doped a Fe2O3 semiconducting nanofibers were prepared by electrospinning over a wide range of Cu molar ratios (fCu 0 0.52 for fCu fFe 1) followed then by pyrolysis in air atmosphere to remove the organic template. Cu favored to substitute some of the Fe cations in the hematite structure to form crystalline cuprospinel (CuFe2O4) phase. The nanofibers exhibited an interesting p to n type transition of semiconducting behavior when fCu was increased above 0.23, as observed from electrical resistance change against oxidative NO2 gas of ppm levels (5 50 ppm) at 300 degC. The sensing response decreased from 2.59 to 1.52 when the CuFe2O4 concentration increases; nonetheless, the presence of CuFe2O4 facilitated adsorption of the NO2 gas, resulted in a shortened response time (up to 40% as fCu was increased to 0.52.
author_names: R Wu

Chun Wei Lin

Wenjea J Tseng
title: Preparation of electrospun Cu doped a Fe2O3 semiconductor nanofibers for NO2 gas sensor
year: 2017