Photosensitive polystyrene/silver bromide hybrid colloidal crystals as recoverable colorimetric naked eye probes for bromine gas sensing

2016 ◽  
Vol 4 (7) ◽  
pp. 1386-1391 ◽  
Author(s):  
Bing Yu ◽  
Feng Zhai ◽  
Hailin Cong ◽  
Di Yang
Keyword(s):  
Linear Relationship ◽  
Gas Sensing ◽  
Colloidal Crystal ◽  
Colloidal Crystals ◽  
Silver Bromide ◽  
Gas Concentration ◽  
Naked Eye ◽  
Light Yellow ◽  
Reliable Performance ◽  
Deep Green

The color of a hybrid colloidal crystal sensor is changed from deep green to light yellow with increased bromine gas concentrations with a linear relationship between the band gap shift and bromine gas concentration. The sensor has a very reliable performance after repeated sensing and regeneration.

scholarly journals Synthesis of magnetic mesoporous titania colloidal crystals through evaporation induced self-assembly in emulsion as effective and recyclable photocatalysts

2015 ◽  
Vol 17 (41) ◽  
pp. 27653-27657 ◽  
Author(s):  
Jeffrey E. Chen ◽  
Hong-Yuan Lian ◽  
Saikat Dutta ◽  
Saad M. Alshehri ◽  
Yusuke Yamauchi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Self Assembly ◽  
Colloidal Crystal ◽  
Colloidal Crystals ◽  
Mesoporous Titania ◽  
Evaporation Induced Self Assembly

This study illustrates the directed self-assembly of mesoporous TiO2 with magnetic properties due to its colloidal crystal structure with Fe3O4.

scholarly journals Effect of GNWs/NiO-WO3/GNWs Heterostructure for NO2 Gas Sensing at Room Temperature

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 626
Author(s):  
Seokhun Kwon ◽  
Seokwon Lee ◽  
Joouk Kim ◽  
Chulmin Park ◽  
Hosung Jung ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Room Temperature ◽  
Microwave Plasma ◽  
Gas Sensing ◽  
Chemical Vapor ◽  
Gas Concentration ◽  
Negative Change ◽  
Low Concentrations ◽  
Detection Characteristics ◽  
No2 Detection

Recently, as air pollution and particulate matter worsen, the importance of a platform that can monitor the air environment is emerging. Especially, among air pollutants, nitrogen dioxide (NO2) is a toxic gas that can not only generate secondary particulate matter, but can also derive numerous toxic gases. To detect such NO2 gas at low concentration, we fabricated a GNWs/NiO-WO3/GNWs heterostructure-based gas sensor using microwave plasma-enhanced chemical vapor deposition (MPECVD) and sputter, and we confirmed the NO2 detection characteristics between 10 and 50 ppm at room temperature. The morphology and carbon lattice characteristics of the sensing layer were investigated using field emission scanning electron microscopy (FESEM) and Raman spectroscopy. In the gas detection measurement, the resistance negative change according to the NO2 gas concentration was recorded. Moreover, it reacted even at low concentrations such as 5–7 ppm, and showed excellent recovery characteristics of more than 98%. Furthermore, it also showed a change in which the reactivity decreased with respect to humidity of 33% and 66%.

scholarly journals Bioinspired hydrogel microfibres colour-encoded with colloidal crystals

2019 ◽  
Vol 6 (9) ◽  
pp. 1938-1943 ◽  
Author(s):  
Zhi-Jun Meng ◽  
Jing Zhang ◽  
Xu Deng ◽  
Ji Liu ◽  
Ziyi Yu ◽  
...  
Keyword(s):  
Colloidal Crystal ◽  
Colloidal Crystals

The integration of microfluidic spinning and colloidal crystal microdots enable the colour-encoded hydrogel microfibres with facile and flexible manipulation of the encoding.

scholarly journals Convenient and Efficient Fabrication of Colloidal Crystals Based on Solidification-Induced Colloidal Assembly

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 575 ◽  
Author(s):  
Ting Shao ◽  
Laixi Sun ◽  
Chun Yang ◽  
Xin Ye ◽  
Shufan Chen ◽  
...  
Keyword(s):  
Driving Force ◽  
Crystallization Process ◽  
Colloidal Crystal ◽  
Colloidal Crystals ◽  
Magnetic Interaction ◽  
Colloidal Assembly ◽  
Water Suspension ◽  
Colloidal Crystallization ◽  
New Strategy ◽  
Crystal Grains

The simple yet efficient and versatile fabrication of colloidal crystals was investigated based on the solidification-induced colloidal crystallization process with particle/water suspension as precursor. The resulting colloidal crystals were constituted by crystal grains with sizes ranging from several tens of micrometers to a few millimeters. Each of the grains had a close-hexagonal array of colloids, which endowed the bulk colloidal crystal powders with some specific optical properties. The freezing of water was shown as the major driving force to form colloidal crystal grains, which supersaturated the solution with nanoparticles and thus induced the formation and growth of colloidal crystal seeds. This process is intrinsically different from those conventional methods based on shearing force, surface tension, columbic interaction or magnetic interaction, revealing a new strategy to fabricate colloidal crystals in a convenient and efficient way.

Analytical modeling of phosphorene-based NO2 gas sensor

2019 ◽  
Vol 33 (14) ◽  
pp. 1950143 ◽  
Author(s):  
Elham Mansouri ◽  
Javad Karamdel ◽  
Mohammad Taghi Ahmadi ◽  
Masoud Berahman
Keyword(s):  
Gas Sensor ◽  
Carrier Mobility ◽  
Analytical Modeling ◽  
Gas Sensing ◽  
High Surface ◽  
Volume Ratio ◽  
Gas Concentration ◽  
Proposed Model ◽  
Gas Sensing Properties ◽  
Acceptable Agreement

Phosphorene is a new two-dimensional material that has great potentials in Nano electronic application, so it has attracted more researchers’ attention nowadays. Indeed, phosphorene is an interesting material in gas sensing, due to its high surface-to-volume ratio and its carrier mobility. Many studies have been reported on phosphorene gas sensing, but there is not enough study on analytical modeling of phosphorene gas sensing properties. In this research, by adopting data from experimental NO2-based gas sensor, an analytical model of the phosphorene gas sensing behavior is presented. Then, the experimental results of NO2 gas sensing are compared with the proposed model and acceptable agreement is reported. This new model is adapted to predict phosphorene gas sensing performance in higher NO2 gas concentrations, which demonstrates, linear relation is established in higher concentrations same as lower ppb NO2 gas concentration. So, we have predicted the result of NO2 gas sensing for higher concentration based on experimental sensing.

Research on the Optical Fiber Gas Sensing System Based on the Gas Concentration Measurement

2012 ◽  
Vol 529 ◽  
pp. 487-491 ◽  
Author(s):  
Bao Hu Gu ◽  
Ze Fa Fang
Keyword(s):  
Optical Fiber ◽  
Gas Sensing ◽  
High Sensitivity ◽  
Gas Absorption ◽  
Concentration Measurement ◽  
Mine Safety ◽  
Social Significance ◽  
Gas Concentration ◽  
Economic Significance ◽  
Mine Gas

At present , the catalytic combustion type gas sensors is still used in our country which is the extensive use of underground coal mine gas detection instrument , this kind of sensor slow response, calibration cycle is short, and the apparatus for the selectivity of methane is poor. Thus it can be seen that develop a safe and reliable, selective, high sensitivity of gas concentration measurement system that for mine safety operation, the personal safety and environment protection has a very important social significance and economic significance. Optical fiber sensing monitoring system according to the gas absorption spectrum principle with double light path structure on the mine gas online monitoring the concentration of the gas, has avoid the explosion, dust and so on many special advantages.

scholarly journals Detection of Emanated Light at the Modified Clad Region (Sno2) of the Optical Fiber for Methanol Gas Sensing

2020 ◽  
Vol 8 (5) ◽  
pp. 3327-3332
Keyword(s):  
Optical Fiber ◽  
Room Temperature ◽  
Gas Sensing ◽  
Output Intensity ◽  
Gas Sensitivity ◽  
Radiation Mode ◽  
Gas Concentration ◽  
Fiber Mode ◽  
Modified Surface ◽  
Different Gases

A leakage detecting sensor (radiation mode (or) double fiber mode) is proposed to monitor the light rays propagates from the surface of the modified clad region (SnO2 ) of the optical fiber. The output intensity increases and decreases for the varying gas concentration (0-500 ppm) with the presence of different gases (methanol, ethanol, acetone and ammonia) at room temperature. The received output intensity from the clad modified surface increases for ammonia and methanol, whereas, it decreases for acetone and ethanol gases for the increase in the gas concentration. However, in the transmitting mode (single fiber mode) the output light intensity decreases for all the gases with varying gas concentration. The output gas sensitivity of the proposed sensor (double fiber mode) is compared with the transmitting mode sensor and the sensor shows superior response for methanol over other gases. The dynamic characteristics of the sensor are reported.

scholarly journals Enhance the gas-sensing performances of graphene oxide (GO) thin films for detecting nitrogen dioxide gas

2021 ◽  
Vol 26 (4) ◽  
Author(s):  
Ali Al-jawdah ◽  
Rathyah Jarrah ◽  
Mohsin Al-Khaykanee ◽  
Mirjam Skof
Keyword(s):  
Thin Films ◽  
Graphene Oxide ◽  
Energy Gap ◽  
Gas Sensing ◽  
Operating Temperature ◽  
Temperature Response ◽  
Absorption Spectrometry ◽  
Optical Energy Gap ◽  
Gas Concentration ◽  
Sensor Applications

In this work, graphene oxide (GO) synthesized via a modified Hummer method was utilized to manufacture thin films for gas sensor applications. The films were prepared on glass substrates using the spin coating technique, the concentration of GO was varied in the precursor liquid. The crystall ographic properties of the prepared GO films were analyzed using XRD and the results showed a polycrystalline structure with a crystallite size of 15.51 nm. Using the weighing method, the average film thickness was determined to be about 200 nm. UV-Vis absorption spectrometry combined with the Tauc method confirmed the indirect nature (allowed and forbidden) of electronic transitions in the samples and it also showed a decrease in the optical energy gap with an increasing amount of GO in the samples. Values for Eg ranged from 2.4 eV to 2.15 eV for allowed transitions and from 3.05 eV to 2.6 eV for forbidden transitions. Gas sensing measurements were performed using NO2 as target gas at different operating temperatures (50, 100, 200 and 300 oC), as well as four target gas concentration (100 ppm, 400 ppm, 700 ppm, and 1000 ppm) have been tested and shows the good response in the range of 10%. It can be seen that the sensitivity increases with increasing operating temperature and gas concentration. At 300 oC operating temperature response and recovery time decrease to their lowest value or 2.6 and 5 seconds, respectively.

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