Limiting the Oxidation of WS2 Nanostructures by Oleylamine Surface Passivation for Room Temperature NH3 Sensing

Oleylamine capped WS2 nanostructures were successfully formed at 320 °C via a relatively simple colloidal route. SEM and TEM analyses showed that the 3D nanoflowers that were initially formed disintegrated into 2D nanosheets after prolonged incubation. XPS and XRD analyses confirmed oxidation of WS2 into WO3. Sensors based on these oleylamine capped WS2 nanoflowers and nanosheets still showed a change in electrical response towards various concentrations of NH3 vapour at room temperature in a 25% relative humidity background despite the oxidation. The nanoflowers exhibited n-type response while the nanosheets displayed a p-type response towards NH3 exposure. The nanoflower based sensors showed better response to NH3 vapour exposure than the nanosheets. The sensors showed a good selectivity towards NH3 relative to acetone, ethanol, chloroform and toluene. Meanwhile, a strong interference of humidity to the NH3 response was displayed at high relative humidity levels. The results demonstrated that oleylamine limited the extent of oxidation of WS2 nanostructures. The superior sensing performance of the nanoflowers can be attributed to their hierarchical morphology which enhances the surface area and diffusion of the analyte.

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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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p-type in ZnO:N by codoping with Cr

MRS Proceedings ◽

10.1557/proc-786-e6.1 ◽

2003 ◽

Vol 786 ◽

Author(s):

E. Kaminska ◽

A. Piotrowska ◽

J. Kossut ◽

R. Butkute ◽

W. Dobrowolski ◽

...

Keyword(s):

Time Scale ◽

Room Temperature ◽

Surface Passivation ◽

Hole Concentration ◽

Rf Sputtering ◽

Zno Films ◽

Type Conductivity ◽

Chromium Doping ◽

P Type ◽

Over Time

ABSTRACTWe report on the fabrication of p-ZnO films by thermal oxidation of Zn3N2 deposited by reactive rf sputtering. With additional chromium doping we achieved p-type conductivity with the hole concentration ∼5×1017cm−3 and the mobility of 23.6 cm2/Vs at room temperature. We developed a method of surface passivation of p-ZnO that maintains its p-type conductivity over time-scale of months.

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Porous Gig-Lox TiO2 Doped with N2 at Room Temperature for P-Type Response to Ethanol

Chemosensors ◽

10.3390/chemosensors7010012 ◽

2019 ◽

Vol 7 (1) ◽

pp. 12 ◽

Cited By ~ 2

Author(s):

Emanuele Smecca ◽

Salvatore Sanzaro ◽

Clelia Galati ◽

Lucio Renna ◽

Leonardo Gervasi ◽

...

Keyword(s):

Tio2 Film ◽

Room Temperature ◽

Electrical Response ◽

High Surface ◽

Volume Ratio ◽

Reactive Sputtering ◽

Deposition Process ◽

Deposition Method ◽

Type Character ◽

P Type

Nanostructured materials represent a breakthrough in many fields of application. Above all for sensing, the use of nanostructures with a high surface/volume ratio is strategic to raise the sensitivity towards dangerous environmental gas species. A new Dc-Reactive sputtering Deposition method has been applied to grow highly porous p-type nitrogen-doped titanium oxide layers by modifying the previously developed reactive sputtering method called gig-lox. The doping of the films was achieved at room temperature by progressive incorporation of nitrogen species during the deposition process. Two different amounts of N2 were introduced into the deposition chamber at flow rates of 2 and 5 standard cubic centimeter per minutes (sccm) for doping. It has been found that the N2 uptake reduces the deposition rate of the TiO2 film whilst the porosity and the roughness of the grown layer are not penalized. Despite the low amount of N2, using 2 sccm of gas resulted in proper doping of the TiO2 film as revealed by XPS Analyses. In this case, nitrogen atoms are mainly arranged in substitutional positions with respect to the oxygen atoms inside the lattice, and this defines the p-type character of the growing layer. Above this strategic structural modification, the multibranched spongy porosity, peculiar of the gig-lox growth, is still maintained. As proof of concept of the achievements, a sensing device was prepared by combining this modified gig-lox deposition method with state-of-the-art hot-plate technology to monitor the electrical response to ethanol gas species. The sensor exhibited a sensitivity of a factor of ≈2 to 44 ppm of ethanol at ≈200 °C as measured by a rise in the layer resistivity according to the p-type character of the material. At the higher temperature of ≈350 °C, the sensor turned to n-type as without doping. This behavior was related to a loss of nitrogen content inside the film during the annealing. It was indeed proved that p-type doping of a gig-lox sponge during growth is feasible, even at room temperature, without losing the layer porosity and the capability to host and detect environmental species. Moreover, the material integration on a device is simply done as the last production step. Easy TiO2 doping procedures, combined with porosity, are of general purpose and interest for several applications even on flexible substrates.

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Room-temperature volatile organic compounds sensing based on WO3·0.33H2O, hexagonal-WO3, and their reduced graphene oxide composites

RSC Advances ◽

10.1039/c6ra16892b ◽

2016 ◽

Vol 6 (107) ◽

pp. 105171-105179 ◽

Cited By ~ 19

Author(s):

T. M. Perfecto ◽

C. A. Zito ◽

D. P. Volanti

Keyword(s):

Graphene Oxide ◽

Volatile Organic Compounds ◽

Relative Humidity ◽

Reduced Graphene Oxide ◽

Organic Compounds ◽

Room Temperature ◽

Reduced Graphene ◽

Volatile Organic ◽

P Type ◽

Oxide Composites

The sensors based on WO3·0.33H2O, RGO-WO3·0.33H2O, h-WO3, and RGO-h-WO3 showed great VOCs sensing properties at room temperature and 55% relative humidity. The materials exhibited a p-type behavior. RGO improved the acetone sensing response.

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Lead-free p-type Mn:Cs3Cu2I5 perovskite with tunable dual-color emission through room-temperature grinding method

Journal of Materials Science ◽

10.1007/s10853-021-06077-9 ◽

2021 ◽

Author(s):

Junfeng Qu ◽

Shuhong Xu ◽

Fan Liu ◽

Zhuyuan Wang ◽

Haibao Shao ◽

...

Keyword(s):

Room Temperature ◽

Lead Free ◽

Grinding Method ◽

Dual Color ◽

P Type ◽

Color Emission

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Role of ALD Al2O3 Surface Passivation on the Performance of p-Type Cu2O Thin Film Transistors

ACS Applied Materials & Interfaces ◽

10.1021/acsami.0c18915 ◽

2021 ◽

Vol 13 (3) ◽

pp. 4156-4164

Author(s):

Mari Napari ◽

Tahmida N. Huq ◽

David J. Meeth ◽

Mikko J. Heikkilä ◽

Kham M. Niang ◽

...

Keyword(s):

Thin Film ◽

Thin Film Transistors ◽

Surface Passivation ◽

Cu2o Thin Film ◽

P Type

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Enhanced room-temperature ethanol sensing performance of porous MoO3/V0.13Mo0.87O2.935 heterostructures self-assembled with 2D nanosheets

CrystEngComm ◽

10.1039/d1ce00311a ◽

2021 ◽

Author(s):

Jia Guo ◽

Hang Li ◽

Shushu Chu ◽

Qi Zhang ◽

Ziqiong Lin ◽

...

Keyword(s):

Room Temperature ◽

Self Assembled ◽

Ethanol Sensing ◽

2D Nanosheets ◽

Sensing Performance

Porous MoO3/V0.13Mo0.87O2.935 heterostructures self-assembled with 2D nanosheets have been primarily prepared by a facile method for effectively detecting ethanol at room temperature. V0.13Mo0.87O2.935 phase contributes to the modified microspheres and...

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Back protection of canvas paintings

Heritage Science ◽

10.1186/s40494-020-00435-7 ◽

2020 ◽

Vol 8 (1) ◽

Author(s):

Tim Padfield ◽

Nicolas Padfield ◽

Daniel Sang-Hoon Lee ◽

Anne Thøgersen ◽

Astrid Valbjørn Nielsen ◽

...

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Relative Humidity ◽

Temperature Variation ◽

Room Temperature ◽

Single Point ◽

Confined Space ◽

Constant Wall Temperature ◽

Back Plate ◽

Inner Surface

Abstract In this paper different scenarios for back protection of a canvas painting and their effect on the stability of the relative humidity behind the painting are tested. A painting on canvas, stretched on a wooden frame, was fitted with various styles of back protection and then exposed to a cycle of temperature variation at the back, with the front exposed to a constant room temperature. The painting was also exposed to a constant wall temperature and varying room temperature. The space between the canvas and the back board was fitted with temperature and relative humidity (RH) sensors. The sensors were used to provide the essential single-point data of temperature and RH at the given locations. For more comprehensive understanding of the rather confined space, further numerical simulation (computational fluid dynamics) was adopted as part of the investigation. The computational fluid dynamics was used to understand the natural convection within the microclimate through the depictions of temperature distribution, as well as the corresponding airflow. The unprotected painting suffered a large RH variation at its back, because of the varying canvas temperature interacting with the constant room air moisture content. Effective stabilisation of the RH behind the canvas against temperature variation was provided by a shiny aluminium alloy sheet sealed against the frame. The non-absorbent back board experienced a strong variation in RH, because of humidity buffering of the space by the painting canvas at a different temperature. Either a space or insulation between this back plate and the wall reduced the risk of condensation on the inner surface of the back plate. Insulation will however increase the risk of condensation on the wall surface behind the painting. An absorbent back board de-stabilised the RH at the painting canvas surface by providing a competing humidity buffer at a different temperature. To provide protection against moisture exchange with an unsuitable room RH, extra humidity buffer was placed 3 mm behind the painting canvas, kept close to the painting temperature by insulation between this buffer and the back board. This stabilised RH at the canvas surface but increased both the temperature and the RH variation at the back board and thus increased the risk of condensation on the inner surface of the back board. The RH and the temperature in the narrow spaces between the painting canvas and the wooden stretcher frame were always more nearly constant than in the open canvas area, which suggests an explanation for the widely observed better condition of the areas of canvas paintings which lie close over the support structure. Our conclusion is that a non-absorbent, impermeable back plate gives good RH stability against a changing temperature gradient between wall and canvas painting surface.

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