Synthesis of nearly monodisperse Co3O4 nanocubes via a microwave-assisted solvothermal process and their gas sensing properties

Facile synthesis of mesoporous hierarchical Co3O4–TiO2 p–n heterojunctions with greatly enhanced gas sensing performance

“…Therefore, there is a need to develop high-performance gas sensors with high sensitivity, low operating temperature and good stability for real-time monitoring of toluene and xylene. A variety of metal oxide semiconductors have been used as sensing materials to detect VOCs, such as ZnO, [4][5][6] SnO2, [7][8][9] In2O3, [10][11][12] Co3O4, [13][14][15] TiO2, 16,17 WO3, [18][19][20][21] Fe2O3, [22][23][24] Cu2O/CuO, 25,26 and NiO. 27 Among these metal oxide semiconductors, Co3O4 is believed to be a promising candidate for sensing of toluene and xylene because of its excellent catalytic activity for oxidizing them at low temperature which results from its larger adsorption amount of oxygen 28 on the surface than others and multivalent properties facilitating redox reactions.…”

“…Wang et al 33 prepared Co3O4 nanorods through a facile one-pot method followed by calcination at 450 ºC and the response of the prepared Co3O4 nanorods to 200 ppm toluene reached 35 at the working temperature of 200 ºC. Sun et al 13 synthesized nearly monodisperse Co3O4 nanocubes via a microwave-assisted solvothermal process and found that Co3O4 nanocubes showed responses of 4.7 and 6.45 to 100 ppm toluene and xylene respectively, at 200 ºC. Though Co3O4 nanomaterials show a response to toluene and xylene in a wide concentration range, the sensitivity is still very low toward toluene and xylene with concentration lower than 50 ppm and the working temperature is relatively high (above 200 ºC), which hinders its practical application in the fields of gas sensors.…”

A highly sensitive BTX sensor based on electrochemically derived wall connected TiO2 nanotubes

“…It is revealed from these reports that efficient sensor response towards BTX (or individuals) was achieved at the expense of high operating temperature (≥ 250°C) [4][5][6][7][8][9][10]. However, relatively low temperature (~25-200°C) BTX sensing has also been reported by some research groups [11][12][13][14][15]. Among these reports, cobalt oxide nanocubes found to offer high response magnitude towards BTX at 200°C [11].…”

“…several metal oxide (Co 3 O 4 , WO 3 , ZnO, Cr 2 O 3 , SnO 2 , TiO 2 etc.) based gas/vapor sensors have been investigated so far to sense the BTX family as a whole or its individual constituents (B, T or X) [4][5][6][7][8][9][10][11][12][13][14][15]. It is revealed from these reports that efficient sensor response towards BTX (or individuals) was achieved at the expense of high operating temperature (≥ 250°C) [4][5][6][7][8][9][10].…”

Optical Waveguide BTX Gas Sensor Based on Yttrium-Doped Lithium Iron Phosphate Thin Film

“…Many works have been done on sensitivity to BTX such as electric noses [3,4], chromatography [5], and electrochemical sensor [6], and these detectors are accurate, yet bulky and expensive, and require higher operating temperature. In comparison, the optical waveguide (OWG) sensors [7][8][9] are small in size, of high sensitivity, of fast response time, monitored at room temperature, and of intrinsically safe detection.…”