P–p heterojunction CuO/CuCo2O4 nanotubes synthesized via electrospinning technology for detecting n-propanol gas at room temperature

2017 ◽  
Vol 4 (7) ◽  
pp. 1219-1230 ◽  
Author(s):  
Khaled Tawfik Alali ◽  
Zetong Lu ◽  
Hongsen Zhang ◽  
Jingyuan Liu ◽  
Qi Liu ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Room Temperature ◽  
Gas Sensing ◽  
Tubular Structure ◽  
Large Specific Surface Area ◽  
Sensing Performance

Composite CuO/CuCo2O4 nanotubes were synthesized by electrospinning technology. The large specific surface area, complex tubular structure, and p–p heterojunction are the potential reasons for the excellent room temperature gas sensing performance toward n-propanol vapor.

scholarly journals Preparation and Application of 2D MXene-Based Gas Sensors: A Review

Chemosensors ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 225
Author(s):  
Qingting Li ◽  
Yanqiong Li ◽  
Wen Zeng
Keyword(s):  
Composite Materials ◽  
Specific Surface ◽  
Surface Area ◽  
Gas Sensor ◽  
Specific Surface Area ◽  
Gas Sensors ◽  
Room Temperature ◽  
Gas Sensing ◽  
Interlayer Spacing ◽  
Preparation Methods

Since MXene (a two-dimensional material) was discovered in 2011, it has been favored in all aspects due to its rich surface functional groups, large specific surface area, high conductivity, large porosity, rich organic bonds, and high hydrophilicity. In this paper, the preparation of MXene is introduced first. HF etching was the first etching method for MXene; however, HF is corrosive, resulting in the development of the in situ HF method (fluoride + HCl). Due to the harmful effects of fluorine terminal on the performance of MXene, a fluorine-free preparation method was developed. The increase in interlayer spacing brought about by adding an intercalator can affect MXene’s performance. The usual preparation methods render MXene inevitably agglomerate and the resulting yields are insufficient. Many new preparation methods were researched in order to solve the problems of agglomeration and yield. Secondly, the application of MXene-based materials in gas sensors was discussed. MXene is often regarded as a flexible gas sensor, and the detection of ppb-level acetone at room temperature was observed for the first time. After the formation of composite materials, the increasing interlayer spacing and the specific surface area increased the number of active sites of gas adsorption and the gas sensitivity performance improved. Moreover, this paper discusses the gas-sensing mechanism of MXene. The gas-sensing mechanism of metallic MXene is affected by the expansion of the lamellae and will be doped with H2O and oxygen during the etching process in order to become a p-type semiconductor. A p-n heterojunction and a Schottky barrier forms due to combinations with other semiconductors; thus, the gas sensitivities of composite materials are regulated and controlled by them. Although there are only several reports on the application of MXene materials to gas sensors, MXene and its composite materials are expected to become materials that can effectively detect gases at room temperature, especially for the detection of NH3 and VOC gas. Finally, the challenges and opportunities of MXene as a gas sensor are discussed.

scholarly journals Surface Structure Engineering of Nanosheet-Assembled NiFe2O4 Fluffy Flowers for Gas Sensing

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 297
Author(s):  
Xiaofeng Wang ◽  
Xu Li ◽  
Guozheng Zhang ◽  
Zihao Wang ◽  
Xue-Zhi Song ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Structure ◽  
Surface Area ◽  
Specific Surface Area ◽  
Photoelectron Spectroscopy ◽  
Gas Sensing ◽  
Nitrogen Adsorption ◽  
X Ray ◽  
Adsorption Desorption ◽  
Sensing Performance

In this work, we present a strategy to improve the gas-sensing performance of NiFe2O4 via a controllable annealing Ni/Fe precursor to fluffy NiFe2O4 nanosheet flowers. X-ray diffraction (XRD), a scanning electron microscope (SEM), nitrogen adsorption–desorption measurements and X-ray photoelectron spectroscopy (XPS) were used to characterize the crystal structure, morphology, specific surface area and surface structure. The gas-sensing performance was tested and the results demonstrate that the response was strongly influenced by the specific surface area and surface structure. The resultant NiFe2O4 nanosheet flowers with a heating rate of 8 °C min−1, which have a fluffier morphology and more oxygen vacancies in the surface, exhibited enhanced response and shortened response time toward ethanol. The easy approach facilitates the mass production of gas sensors based on bimetallic ferrites with high sensing performance via controlling the morphology and surface structure.

scholarly journals C2H5OH and NO2 sensing properties of ZnO nanostructures: correlation between crystal size, defect level and sensing performance

RSC Advances ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 5629-5639 ◽  
Author(s):  
Chu Thi Quy ◽  
Nguyen Xuan Thai ◽  
Nguyen Duc Hoa ◽  
Dang Thi Thanh Le ◽  
Chu Manh Hung ◽  
...  
Keyword(s):  
Nitrogen Dioxide ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Crystal Size ◽  
Gas Sensing ◽  
Zno Nanostructures ◽  
Defect Level ◽  
Sensing Applications ◽  
Sensing Performance

ZnO nanostructures were synthesized for ethanol and nitrogen dioxide gas-sensing applications. Results pointed out that the defect levels dominating the gas-sensing performance but not the morphology, specific surface area or crystal size.

Nanoflake assembled hierarchical porous flower-like α-Fe2O3 with large specific surface area for enhanced acetone sensing

2020 ◽  
Vol 13 (06) ◽  
pp. 2051038
Author(s):  
Jianxia Zhang ◽  
Li Liu ◽  
Xiaonian Tang ◽  
Dan Sun ◽  
Chunxia Tian ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Calcination Temperature ◽  
Specific Surface Area ◽  
Gas Sensing ◽  
High Porosity ◽  
Large Specific Surface Area ◽  
Minimum Concentration ◽  
Maximum Value ◽  
Hierarchical Porous

High porosity [Formula: see text]-Fe2O3 has attracted a lot of attention due to its exceptional structure. In this paper, nanoflake assembled hierarchical porous flower-like [Formula: see text]-Fe2O3 was prepared by hydrothermal and calcination methods without any additional templates. Scanning electron microscopy (SEM) morphological characterization results show that with the increase of calcination temperature (400∘C, 450∘C, 500∘C, 550∘C, 600∘C), pores appeared. However, the results of nitrogen adsorption show that the specific surface area of the [Formula: see text]-Fe2O3 reaches the maximum value (52.19[Formula: see text]m2/g) when the calcination temperature is 500∘C. The gas sensing performance of flower-like [Formula: see text]-Fe2O3 with different calcination temperature is compared, interestingly, with the increase of calcination temperature, the response of the samples increased first and then decreased, and reached the maximum value (44.2–100 parts per million (ppm) acetone) when the calcination temperature was 500∘C. The minimum concentration for acetone was 200 ppb (response value is 2.0). Moreover, calcined at 500∘C, hierarchical porous [Formula: see text]-Fe2O3 has a fast response recovery (4/25 s) and low working temperature (210∘C). These excellent gas sensing properties are mainly due to porous structure, large specific surface area, and oxygen vacancies on the surface, which make it a promising material for acetone sensors.

scholarly journals Effective 3D open-channel nanostructures of a MgMn2O4 positive electrode for rechargeable Mg batteries operated at room temperature

2021 ◽  
Author(s):  
Kazuki Sone ◽  
Yoshihiro Hayashi ◽  
Toshihiko Mandai ◽  
Shunsuke Yagi ◽  
Yuya Oaki ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Room Temperature ◽  
Open Channel ◽  
Positive Electrode ◽  
Large Specific Surface Area ◽  
Channel Network ◽  
Coin Cell

Room-temperature operations of rechargeable Mg coin-cell batteries have been achieved using a spinel MgMn2O4 powder having a large specific surface area > 200 m2 g–1 and more than 90% porosity with a triple-tiered 3D open-channel network.

scholarly journals Recent Trends and Developments in Graphene/Conducting Polymer Nanocomposites Chemiresistive Sensors

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3311 ◽  
Author(s):  
Golnoush Zamiri ◽  
A. S. M. A. Haseeb
Keyword(s):  
Conducting Polymers ◽  
Specific Surface ◽  
Surface Area ◽  
Polymer Nanocomposites ◽  
Conducting Polymer ◽  
Specific Surface Area ◽  
Self Assembly ◽  
Gas Sensing ◽  
In Situ Polymerization ◽  
Large Specific Surface Area

The use of graphene and its derivatives with excellent characteristics such as good electrical and mechanical properties and large specific surface area has gained the attention of researchers. Recently, novel nanocomposite materials based on graphene and conducting polymers including polyaniline (PANi), polypyrrole (PPy), poly (3,4 ethyldioxythiophene) (PEDOT), polythiophene (PTh), and their derivatives have been widely used as active materials in gas sensing due to their unique electrical conductivity, redox property, and good operation at room temperature. Mixing these two materials exhibited better sensing performance compared to pure graphene and conductive polymers. This may be attributed to the large specific surface area of the nanocomposites, and also the synergistic effect between graphene and conducting polymers. A variety of graphene and conducting polymer nanocomposite preparation methods such as in situ polymerization, electropolymerization, solution mixing, self-assembly approach, etc. have been reported and utilization of these nanocomposites as sensing materials has been proven effective in improving the performance of gas sensors. Review of the recent research efforts and developments in the fabrication and application of graphene and conducting polymer nanocomposites for gas sensing is the aim of this review paper.

scholarly journals Nanocomposite Materials Based on Electrochemically Synthesized Graphene Polymers: Molecular Architecture Strategies for Sensor Applications

Chemosensors ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 149
Author(s):  
André Olean-Oliveira ◽  
Gilberto A. Oliveira Brito ◽  
Celso Xavier Cardoso ◽  
Marcos F. S. Teixeira
Keyword(s):  
Conducting Polymers ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Electrochemical Sensors ◽  
Structural Characteristics ◽  
Low Cost ◽  
Large Specific Surface Area ◽  
Molecular Architecture ◽  
Sensor Applications

The use of graphene and its derivatives in the development of electrochemical sensors has been growing in recent decades. Part of this success is due to the excellent characteristics of such materials, such as good electrical and mechanical properties and a large specific surface area. The formation of composites and nanocomposites with these two materials leads to better sensing performance compared to pure graphene and conductive polymers. The increased large specific surface area of the nanocomposites and the synergistic effect between graphene and conducting polymers is responsible for this interesting result. The most widely used methodologies for the synthesis of these materials are still based on chemical routes. However, electrochemical routes have emerged and are gaining space, affording advantages such as low cost and the promising possibility of modulation of the structural characteristics of composites. As a result, application in sensor devices can lead to increased sensitivity and decreased analysis cost. Thus, this review presents the main aspects for the construction of nanomaterials based on graphene oxide and conducting polymers, as well as the recent efforts made to apply this methodology in the development of sensors and biosensors.

Three-dimensional graphene encapsulated hollow CoSe2-SnSe2 nanoboxes for high performance asymmetric supercapacitors

2022 ◽  
Author(s):  
Kainan Li ◽  
Ke Zheng ◽  
Zhifang Zhang ◽  
Kuan Li ◽  
Ziyao Bian ◽  
...  
Keyword(s):  
Electrochemical Performance ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Active Sites ◽  
Specific Capacity ◽  
Three Dimensional ◽  
Hollow Structure ◽  
Large Specific Surface Area ◽  
Composite Aerogel

Abstract Construction of metal selenides with a large specific surface area and a hollow structure is one of the effective methods to improve the electrochemical performance of supercapacitors. However, the nano-material easily agglomerates due to the lack of support, resulting in the loss of electrochemical performance. Herein, we successfully design a three-dimensional graphene (3DG) encapsulation-protected hollow nanoboxes (CoSe2-SnSe2) composite aerogel (3DG/CoSe2-SnSe2) via a co-precipitation method coupled with self-assembly route, followed by a high temperature selenidation strategy. The obtained aerogel possesses porous 3DG conductive network, large specific surface area and plenty of reactive active sites. It could be used as a flexible and binder-free electrode after a facile mechanical compression process, which provided a high specific capacitance of 460 F g-1 at 0.5 A g-1, good rate capability of 212.7 F g-1 at 10 A g-1, and excellent cycle stability due to the fast electron/ion transfer and electrolyte diffusion. With the as-prepared 3DG/CoSe2-SnSe2 as positive electrodes and the AC (activated carbon) as negative electrodes, an asymmetric supercapacitor (3DG/CoSe2-SnSe2//AC) was fabricated, which delivered a high specific capacity of 38 F g-1 at 1A g-1 and an energy density of 11.89 W h kg-1 at 749.9 W kg-1, as well as a capacitance retention of 91.1% after 3000 cycles. This work provides a new method for preparing electrode material.

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