Evaluation Humidity Sensing Properties of Graphene/HS-TiO2 Nanocomposites

2021 ◽  
Vol 21 (10) ◽  
pp. 5143-5149
Author(s):  
Zhen Zhu ◽  
Wang-De Lin
Keyword(s):  
Room Temperature ◽  
Response Times ◽  
Sol Gel ◽  
Hollow Spheres ◽  
High Sensitivity ◽  
Humidity Sensing ◽  
X Ray ◽  
Transmission Electron ◽  
Recovery Times ◽  
Relative Humidity Range

This paper reports on a nanocomposite synthesized by sol–gel procedure comprising graphene sheets with hollow spheres of titanium dioxide (G/HS-TiO2) with varying weight percentages of graphene for the purpose of humidity sensors. The surface morphology of the nanocomposite was characterized using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The structural properties were examined using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The response to 12–80% RH at room temperature exhibited sensitivity (S = 135). However, the relative humidity range of 12–90% at room temperature exhibited higher sensitivity (S = 557). Sensors fabricated using the proposed nanocomposite exhibited high sensitivity to humidity, high stability, rapid response times, and rapid recovery times with hysteresis error of less than 1.79%. These results demonstrate the outstanding potential of his material for the monitoring of atmospheric humidity. This study also sought to elucidate the mechanisms underlying humidity sensing performance.

scholarly journals Photo-acoustic properties of nanoTiO2:Er

2016 ◽  
Vol 5 (4) ◽  
pp. 196
Author(s):  
R. Palomino-Merino ◽  
R. Lozada-Morales ◽  
J. Martínez-Juárez ◽  
G. Juárez-Díaz ◽  
J. Carmona-Rodriguez ◽  
...  
Keyword(s):  
Room Temperature ◽  
Sol Gel ◽  
Acoustic Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Electron Dispersion ◽  
Er Doped ◽  
Spectroscopy Optical

Nanocrystalline Er-doped TiO2 was prepared by sol-gel at room temperature. X-ray diffraction, photoacoustic spectroscopy (optical absorption), transmission electron microscopy (TEM), and electron dispersion microscopy (EDS) were carried out on both as-prepared and thermally-annealed (air at 700 ºC) samples, revealing the anatase crystalline phase of TiO2. The samples exhibit an average grain size from 38 to 5.1 nm, as the nominal concentration of Er varies from 0 % to 7 %. The photoacoustic spectra evidence the absorption edge at 300 nm attributed to TiO2, as well as several electronic transitions which are atomic energy absorption-line levels characteristics of Er.

Ultrafast Response Humidity Sensor Based on Electrospun Porous BaTiO3 Nanofibers

2013 ◽  
Vol 319 ◽  
pp. 43-48 ◽  
Author(s):  
Hong Di Zhang ◽  
Chen Hao Sheng ◽  
Bin Sun ◽  
Yun Ze Long
Keyword(s):  
Electron Microscope ◽  
Recovery Time ◽  
Room Temperature ◽  
Humidity Sensor ◽  
Humidity Sensing ◽  
X Ray ◽  
Transmission Electron ◽  
Porous Microstructure ◽  
Humidity Sensing Properties ◽  
Scanning Electron

Nanocrystalline and porous barium titanate (BaTiO3) nanofibers with diameter 200-400 nm were synthesized via electrospinning and followed calcinations. The morphology and microstructure of the nanofibers were characterized using field emission scanning electron microscope, X-ray diffractometer and transmission electron microscope, respectively. And the electrical and humidity sensing properties of the nanofibers were also measured. The results reveal that the BaTiO3 nanofibers have a conductivity of about 0.3 S/cm, and show an ultrafast response time (~0.7 s) and a recovery time (~0.4 s) to humidity at room temperature. In addition, the sensing mechanism was also discussed briefly based on its nanocrystalline and porous microstructure of the electrospun material.

scholarly journals Preparation and Magnetic Properties of ZnFe2O4Nanotubes

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Yan Xu ◽  
Yantian Liang ◽  
Lijuan Jiang ◽  
Huarui Wu ◽  
Hongzhi Zhao ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Room Temperature ◽  
Sol Gel ◽  
Anodic Aluminum Oxide Template ◽  
Blocking Temperature ◽  
Outer Diameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Anodic Aluminum ◽  
Transmission Electron

Ordered ZnFe2O4nanotube arrays with the average outer diameter of 100 nm were prepared in porous anodic aluminum oxide template using an improved sol-gel approach. The morphology was studied by transmission electron and field emission scanning electron microscope. X-ray diffraction result shows that the nanotubes were polycrystalline in structure. The magnetic properties of the prepared ZnFe2O4nanotubes were also studied. The results show that the sample shows typical superparamagnetism at room temperature and obvious ferromagnetism below blocking temperature.

Facile Sol-Gel Synthesis of Mesoporous TiO2 in Ionic Liquids

2013 ◽  
Vol 389 ◽  
pp. 53-56
Author(s):  
Shu Guo ◽  
Sheng Xu Lu ◽  
Hui Ding ◽  
Zai Feng Shi
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Sol Gel ◽  
Rutile Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carboxylate Groups ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Sol Gel Synthesis

The mesoporous TiO2 particles was conveniently prepared in a room temperature ionic liquid (RTILs) of 1, 3-di-(3-propionyloxy) imdazolium tetrafluoroborate [DiprCOOBF4 system. The obtained materials were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and N2 adsorptiondesorption analysis. XRD patterns revealed that only rutile phase is formed in the RTILs. The TEM micrographs as well as N2 adsorptiondesorption measurements show that the prepared products exhibited wormlike pore structures. The FTIR (Fourier Transform Infrared Spectra) demonstrate the carboxylate groups attach via bidentate or bridging coordination to the TiO2 surface.

Size-controlled synthesis of nanocrystalline BaTiO3 by a sol-gel type hydrolysis in microemulsion-provided nanoreactors

1998 ◽  
Vol 13 (11) ◽  
pp. 3174-3180 ◽  
Author(s):  
Ch. Beck ◽  
W. Härtl ◽  
R. Hempelmann
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Sol Gel ◽  
Controlled Synthesis ◽  
Sintering Process ◽  
Line Broadening ◽  
X Ray ◽  
Transmission Electron ◽  
Hydrolysis Of ◽  
Size Controlled

Using the hydrolysis of appropriate alkoxide mixtures in water-in-oil microemulsions, nanocrystalline BaTiO3 has been prepared in the form of nonaggregated, cube-shaped crystals at room temperature without any sintering process as is demonstrated by means of x-ray diffractograms and transmission electron micrographs. By variation of the length of the hydrophilic part of the surfactant molecules, the diameter of the water droplets in the microemulsions could be tuned to values between 8 and 55 nm as determined by dynamic light scattering. The size of the resulting nano-BaTiO3 (6 nm ≤ 〈d〉vol ≤ 17 nm) was evaluated from the line broadening of x-ray reflections and correlates to the droplet size. The particle size distribution is very narrow, and in some cases nearly monodisperse.

scholarly journals Aligned Grid Shaped NiO Nanowires for Humidity Sensing at Room Temperature

2020 ◽  
Author(s):  
Masoumeh Mohammadi ◽  
Mohammad Almasi-Kashi ◽  
Somayeh Fardindoost ◽  
Azam Iraji zad
Keyword(s):  
Room Temperature ◽  
Ionic Conduction ◽  
X Ray Diffraction ◽  
Ac Impedance Spectroscopy ◽  
Humidity Sensing ◽  
Electrodeposition Process ◽  
X Ray ◽  
Response Recovery ◽  
Recovery Times ◽  
Sensing Characteristics

Abstract A grid configuration based on the aligned nickel oxide nanowire (NiO NW) for humidity sensing were fabricated through the oxidation of ferromagnetic nickel NWs prepared by a template-assisted electrodeposition process. Their structure and elemental compositions were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and energy-dispersive X-ray analyses (EDAX). The room-temperature humidity sensing behavior of the NiO NWs was investigated successfully based on DC and AC impedance spectroscopy (IS) method in frequencies range 10 Hz to 2 MHz. The sensors showed excellent humidity sensing characteristics such as a high response of about 66 with rather rapid response-recovery times about 9 and 2 s for 90%RH, and good stability. The equivalent circuits were simulated for impedance responses to humidity in the range of 40–90% RH. According to the results, ionic conduction via NW-NW junctions as well as NW-electrode interfaces in the grid configuration is responsible for sensing behavior.

Fabrication, structural and humidity sensing properties of BaTiO3 nanofibers via electrospinning

2015 ◽  
Vol 29 (12) ◽  
pp. 1550066 ◽  
Author(s):  
Chen-Hao Sheng ◽  
Hong-Di Zhang ◽  
Shuai Chen ◽  
Jun-Cheng Zhang ◽  
Wen-Peng Han ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Recovery Time ◽  
Room Temperature ◽  
Electrospinning Technique ◽  
Humidity Sensing ◽  
X Ray ◽  
Sensing Properties ◽  
Transmission Electron ◽  
Humidity Sensitivity ◽  
Humidity Sensing Properties

Barium titanate (BTO) nanofibers were synthesized by electrospinning and followed calcination. The morphologies and microstructures of the nanofibers were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Calcinating temperature and process greatly influenced the surface morphology of the nanofibers. In addition, parallel BTO nanofibers were also successfully produced by a centrifugal electrospinning technique. And the humidity sensing properties of the nanofibers were measured. The results showed an ultrafast response time (~0.5 s) and a recovery time (~0.4 s) to humidity at room temperature, which revealed excellent humidity sensitivity performance.

scholarly journals Hydrothermal Synthesis ofSnO2Nanostructures with Different Morphologies and Their Optical Properties

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Lin Tan ◽  
Lihong Wang ◽  
Yude Wang
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Sol Gel ◽  
Hollow Spheres ◽  
Sodium Dodecyl ◽  
X Ray Diffraction ◽  
Room Temperature Photoluminescence ◽  
Tin Chloride ◽  
Transmission Electron ◽  
High Resolution Tem

SnO2hollow spheres and nanorods were prepared by an aqueous sol-gel route involving the reaction of tin chloride and sodium dodecyl sulphate (SDS) in hexanol and heptane under the different hydrothermal treating temperature and time. X-ray diffraction (XRD) spectra, Fourier transformed infrared (FTIR) spectrum, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and Raman spectroscopy were used to examine the morphology and microstructure to find out the cause. The result indicates that the products are hollow spheres with diameters of approximately 200–900 nm and shell thickness of 60–70 nm via hydrothermal treating at 160°C and one-dimensional rod-like nanostructures with diameters of approximately 20–40 nm and lengths of 100–300 nm via hydrothermal treating at 180 and 200°C, respectively. Room-temperature photoluminescence (PL) properties were investigated under the excitation of 275 nm. The samples exhibited the emission peaks of room-temperature photoluminescence.

scholarly journals Synthesis and acetone sensing properties of ZnFe2O4/rGO gas sensors

2019 ◽  
Vol 10 ◽  
pp. 2516-2526 ◽  
Author(s):  
Kaidi Wu ◽  
Yifan Luo ◽  
Ying Li ◽  
Chao Zhang
Keyword(s):  
Electron Microscopy ◽  
Gas Sensors ◽  
Gas Sensing ◽  
Hollow Spheres ◽  
High Sensitivity ◽  
Inert Atmosphere ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Reduced Graphene

Hollow spheres of pure ZnFe2O4 and of composites of ZnFe2O4 and reduced graphene oxide (rGO) with different rGO content were prepared via a simple solvothermal method followed by a high-temperature annealing process in an inert atmosphere. The X-ray diffraction analysis confirmed that the introduction of rGO had no effect on the spinel structure of ZnFe2O4. In addition, the results of field-emission scanning electron microscopy and (high-resolution) transmission electron microscopy indicated that the synthesized samples had the structure of hollow spheres distributed uniformly onto rGO nanosheets. The diameters of the spheres were determined as about 600–1000 nm. The gas sensing test revealed that the introduction of rGO improved the performance of the sensing of acetone to low concentration, and the ZnFe2O4/rGO composite gas sensor containing 0.5 wt % of rGO exhibited a high sensitivity in sensing test using 0.8–100 ppm acetone at 200 °C. The response of the 0.5 wt % ZnFe2O4/rGO sensor to 0.8 ppm acetone was 1.50, and its response to 10 ppm acetone was 8.18, which is around 2.6 times more pronounced than the response of pure ZnFe2O4 (10 ppm, 3.20). Moreover, the sensor showed a wide linear range and good selectivity.

Study of the Synthesis and Photocatalytic Properties of Iron-Doped Titania Nanocrystallines at Room Temperature

2012 ◽  
Vol 562-564 ◽  
pp. 255-259
Author(s):  
Zhi Hao Wei ◽  
Min Zhong ◽  
Yin Deng
Keyword(s):  
Room Temperature ◽  
Sol Gel ◽  
Photocatalytic Properties ◽  
Iron Doping ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Iron Doped ◽  
Doped Titania ◽  
Average Size

Iron-doped titania (TiO2) nanocrystalline were prepared by sol-gel method at room temperature. The samples were characterized by using transmission electron microscope, X-ray diffractometer and ultaviolet-visible spectrophotometer. X-ray diffraction shows that iron-doped titania have the titania anatase and brookite structure, and the more iron doped in, the less titania brookite structure. When the doping content of 10at% iron, the titania brookite structure disappear absolutely. Transmission electron microscopy shows that with the increase of iron-doping from 0.00 to 0.25, the average size of the grains decrease from 5.7nm to 4.3nm. And samples have higher crystallinity. Using UV-visible spectrophotometer to measure its photocatalytic properties the results show that it has the highest rate of 60% photocatalytic degradation when it is absorbed in methylorange in two hours. With the increase of iron-doping from 0.00 to 0.25, the more iron doped in, the higher photocatalytic properties.

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