Self-Assembled Vanadium Oxide Nanoflakes for p-Type Ammonia Sensors at Room Temperature

VO2(B), VO2(M), and V2O5 are the most famous compounds in the vanadium oxide family. Here, their gas-sensing properties were investigated and compared. VO2(B) nanoflakes were first self-assembled via a hydrothermal method, and then VO2(M) and V2O5 nanoflakes were obtained after a heat-phase transformation in nitrogen and air, respectively. Their microstructures were evaluated using X-ray diffraction and scanning and transmission electron microscopies, respectively. Gas sensing measurements indicated that VO2(M) nanoflakes were gas-insensitive, while both VO2(B) and V2O5 nanoflakes were highly selective to ammonia at room temperature. As ammonia sensors, both VO2(B) and V2O5 nanoflakes showed abnormal p-type sensing characteristics, although vanadium oxides are generally considered as n-type semiconductors. Moreover, V2O5 nanoflakes exhibited superior ammonia sensing performance compared to VO2(B) nanoflakes, with one order of magnitude higher sensitivity, a shorter response time of 14–22 s, and a shorter recovery time of 14–20 s. These characteristics showed the excellent potential of V2O5 nanostructures as ammonia sensors.

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Reversible Room Temperature H2 Gas Sensing Based on Self-Assembled Cobalt Oxysulfide

Sensors ◽

10.3390/s22010303 ◽

2021 ◽

Vol 22 (1) ◽

pp. 303

Author(s):

Hui Zhou ◽

Kai Xu ◽

Nam Ha ◽

Yinfen Cheng ◽

Rui Ou ◽

...

Keyword(s):

Room Temperature ◽

Elevated Temperatures ◽

Gas Sensing ◽

Low Cost ◽

High Sensitivity ◽

Cobalt Sulfide ◽

Bandgap Energy ◽

Gas Molecules ◽

Self Assembled ◽

P Type

Reversible H2 gas sensing at room temperature has been highly desirable given the booming of the Internet of Things (IoT), zero-emission vehicles, and fuel cell technologies. Conventional metal oxide-based semiconducting gas sensors have been considered as suitable candidates given their low-cost, high sensitivity, and long stability. However, the dominant sensing mechanism is based on the chemisorption of gas molecules which requires elevated temperatures to activate the catalytic reaction of target gas molecules with chemisorbed O, leaving the drawbacks of high-power consumption and poor selectivity. In this work, we introduce an alternative candidate of cobalt oxysulfide derived from the calcination of self-assembled cobalt sulfide micro-cages. It is found that the majority of S atoms are replaced by O in cobalt oxysulfide, transforming the crystal structure to tetragonal coordination and slightly expanding the optical bandgap energy. The H2 gas sensing performances of cobalt oxysulfide are fully reversible at room temperature, demonstrating peculiar p-type gas responses with a magnitude of 15% for 1% H2 and a high degree of selectivity over CH4, NO2, and CO2. Such excellent performances are possibly ascribed to the physisorption dominating the gas–matter interaction. This work demonstrates the great potentials of transition metal oxysulfide compounds for room-temperature fully reversible gas sensing.

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Intrinsic n- and p-Type MgZnO Nanorods for Deep-UV Detection and Room-Temperature Gas Sensing

The Journal of Physical Chemistry C ◽

10.1021/acs.jpcc.5b10120 ◽

2015 ◽

Vol 119 (52) ◽

pp. 29186-29192 ◽

Cited By ~ 6

Author(s):

Ruey-Chi Wang ◽

Yu-Xian Lin ◽

Jia-Jun Wu

Keyword(s):

Room Temperature ◽

Gas Sensing ◽

Uv Detection ◽

Deep Uv ◽

P Type

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Electrophoretic deposition of Au NPs on CNT networks for sensitive NO<sub>2</sub> detection

Journal of Sensors and Sensor Systems ◽

10.5194/jsss-3-245-2014 ◽

2014 ◽

Vol 3 (2) ◽

pp. 245-252 ◽

Cited By ~ 3

Author(s):

E. Dilonardo ◽

M. Penza ◽

M. Alvisi ◽

C. Di Franco ◽

D. Suriano ◽

...

Keyword(s):

Electron Microscopy ◽

Photoelectron Spectroscopy ◽

Gas Sensing ◽

Spectroscopic Characterization ◽

Core Diameter ◽

Au Nps ◽

Transmission Electron ◽

P Type ◽

Reducing Gases ◽

The Impact

Abstract. In the present study, Au-surfactant core-shell colloidal nanoparticles (NPs) with controlled dimension and composition were synthesized by sacrificial anode electrolysis. Transmission electron microscopy (TEM) revealed that Au NPs core diameter is between 8 and 12 nm, as a function of the electrosynthesis conditions. Moreover, surface spectroscopic characterization by X-ray photoelectron spectroscopy (XPS) analysis confirmed the presence of nanosized gold phase. Controlled amounts of Au NPs were then deposited electrophoretically on carbon nanotube (CNT) networked films. The resulting hybrid materials were morphologically and chemically characterized using TEM, SEM (scanning electron microscopy) and XPS analyses, which revealed the presence of nanoscale gold, and its successful deposition on CNTs. Au NP/CNT networked films were tested as active layers in a two-pole resistive NO2 sensor for sub-ppm detection in the temperature range of 100–200 °C. Au NP/CNT exhibited a p-type response with a decrease in the electrical resistance upon exposure to oxidizing NO2 gas and an increase in resistance upon exposure to reducing gases (e.g. NH3). It was also demonstrated that the sensitivity of the Au NP/CNT-based sensors depends on Au loading; therefore, the impact of the Au loading on gas sensing performance was investigated as a function of the working temperature, gas concentration and interfering gases.

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Characteristics of point defects on the room temperature ferromagnetic and highly NO2 selectivity gas sensing of p-type Mn3O4 nanorods

Sensors and Actuators B Chemical ◽

10.1016/j.snb.2019.01.007 ◽

2019 ◽

Vol 285 ◽

pp. 92-107 ◽

Cited By ~ 35

Author(s):

Ioannis Kortidis ◽

Hendrik C. Swart ◽

Suprakas Sinha Ray ◽

David E. Motaung

Keyword(s):

Point Defects ◽

Room Temperature ◽

Gas Sensing ◽

P Type

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Highly sensitive and selective room-temperature NO2 gas-sensing characteristics of SnOX-based p-type thin-film transistor

Sensors and Actuators B Chemical ◽

10.1016/j.snb.2019.03.046 ◽

2019 ◽

Vol 288 ◽

pp. 625-633 ◽

Cited By ~ 14

Author(s):

Hwan-Seok Jeong ◽

Min-Jae Park ◽

Soo-Hun Kwon ◽

Hyo-Jun Joo ◽

Hyuck-In Kwon

Keyword(s):

Thin Film ◽

Room Temperature ◽

Gas Sensing ◽

Thin Film Transistor ◽

Highly Sensitive ◽

P Type ◽

Sensing Characteristics

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A Room Temperature Gas Sensor Based on Sulfonated SWCNTs for the Detection of NO and NO2

Sensors ◽

10.3390/s19051116 ◽

2019 ◽

Vol 19 (5) ◽

pp. 1116 ◽

Cited By ~ 6

Author(s):

Eusebiu Ionete ◽

Stefan Spiridon ◽

Bogdan Monea ◽

Elena Stratulat

Keyword(s):

Room Temperature ◽

Gas Sensing ◽

Electrical Response ◽

Long Term Stability ◽

Sensing Applications ◽

Specific Configuration ◽

P Type ◽

Walled Carbon Nanotubes ◽

Type Response

The electrical response of sulfonated single-walled carbon nanotubes (SWCNTs) to NO and NO2, for gas sensing applications, at room temperature, is reported in this work. A specific configuration based on SWCNT deposition between double pair configuration gold electrodes, supported on a substrate, was considered for the sensing device; employed characterization technique where FTIR and SEM. The experimental results showed a p-type response of the sulfonated SWCNTs, with decrease in resistance, under exposure to NO gas (40–200 ppb) and NO2 (40–200 ppb). Also, the sensor responses to successive exposures at NO2 800 ppb together with investigation of long term stability, at 485 ppb for NO, are reported. The reaction mechanism in case of NO and NO2 detection with sulfonated SWCNTs is presented.

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Sensing Properties of CNT hybrid MOS-based Sensors

MRS Proceedings ◽

10.1557/proc-828-a2.6 ◽

2004 ◽

Vol 828 ◽

Cited By ~ 1

Author(s):

Wei-Jen Liou ◽

Tsung-Yeh Yang ◽

Kuang-Nan Lin ◽

Ching-Hong Yang ◽

Hong-Ming Lin

Keyword(s):

Electron Microscopy ◽

Gas Adsorption ◽

Gas Sensing ◽

Sol Gel ◽

Gas Sensitivity ◽

Sensing Properties ◽

Operation Temperature ◽

Transmission Electron ◽

Lower Temperature ◽

P Type

ABSTRACTThe carbon nanotubes provide large surface that can enhance the gas adsorption properties and increase the conductivity at a lower temperature for gas sensing. The gas sensing properties of the hybrid TiO2/CNTs material are examined in this study. The sol-gel technique is used to prepare a thin layer of nano-TiO2 coated on CNTs. The structure of TiO2/CNTs hybrid materials is identified by X-ray diffraction (XRD) and Raman spectrum. The granules and surface morphology are analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrical properties of the hybrid TiO2/CNTs indicate that the operation temperature can be lowered to ambient temperature and this will enhance the gas sensitivity for detecting CO gas. The n-type or p-type behavior of hybrid TiO2/CNTs can be controlled by the coating thickness of hybrid TiO2. According to the image results, the mechanisms of the n-type and p-type behavior of hybrid TiO2/CNTs system are proposed.

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N-doped reduced graphene oxide for room-temperature NO gas sensors

Scientific Reports ◽

10.1038/s41598-021-99883-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Yu-Sung Chang ◽

Feng-Kuan Chen ◽

Du-Cheng Tsai ◽

Bing-Hau Kuo ◽

Fuh-Sheng Shieu

Keyword(s):

Graphene Oxide ◽

Reduced Graphene Oxide ◽

Room Temperature ◽

Gas Sensing ◽

Ambient Conditions ◽

Gas Sensitivity ◽

Nitrogen Doped ◽

Low Concentrations ◽

Reduced Graphene ◽

P Type

AbstractIn this study, we use nitrogen-doped to improving the gas-sensing properties of reduced graphene oxide. Graphene oxide was prepared according to a modified Hummers’ method and then nitrogen-doped reduced graphene oxide (N-rGO) was synthesized by a hydrothermal method using graphene oxide and NH4OH as precursors. The rGO is flat and smooth with a sheet-like morphology while the N-rGO exhibits folded morphology. This type of folding of the surface morphology can increase the gas sensitivity. The N-rGO and the rGO sensors showed n-type and p-type semiconducting behaviors in ambient conditions, respectively, and were responsive to low concentrations of NO gases (< 1000 ppb) at room temperature. The gas-sensing results showed that the N-rGO sensors could detect NO gas at concentrations as low as 400 ppb. The sensitivity of the N-rGO sensor to 1000 ppb NO (1.7) is much better than that of the rGO sensor (0.012). Compared with pure rGO, N-rGO exhibited a higher sensitivity and excellent reproducibility.

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Butane Sensing Property of Si-ZnO Nanowires p-n Junction

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.364.260 ◽

2011 ◽

Vol 364 ◽

pp. 260-265 ◽

Cited By ~ 3

Author(s):

T.Y. Tiong ◽

Chang Fu Dee ◽

M.M. Salleh ◽

Majlis B. Yeop ◽

M. Yahaya

Keyword(s):

Room Temperature ◽

Gas Sensing ◽

Zno Nanowires ◽

Vapour Transport ◽

Initial State ◽

Resistance Change ◽

Boron Doped ◽

Doped Silicon ◽

Minimum Power Consumption ◽

P Type

The p-n junction has been formed by using p-type boron doped silicon and n-type ZnO nanowires (NWs). It was prepared by using simple vapour-transport deposition method. Gas sensing property has been examined by measuring the resistance change of the junction sample towards 1 % of butane gas at room temperature. Significant improvement of sensing behaviour was observed from the fabricated junction sample when it was compared to sample of non-p-n junction ZnO NWs. The increase in the sensitivity of the p-n junction ZnO NWs and the ability to regain the sensing power by returning back to the initial state at room temperature are useful for future sensing device with minimum power consumption. Keywords: ZnO nanowires, Si-ZnO nanowires p-n junction, room temperature sensing and butane gas

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