Abstract
We report a facile and robust room-temperature NO2 sensor fabricated using bi- and multi-layered 2H variant of tungsten di-selenide (2H-WSe2) nanosheets, exhibiting high sensing characteristics. A simple liquid-assisted exfoliation of 2H-WSe2, prepared using ambient pressure chemical vapor deposition, allows smooth integration of these nanosheets on transducers. Three sensor batches are fabricated by modulating the total number of layers (L) obtained from the total number of droplets from a homogeneous 2H-WSe2 dispersion, such as ∼2L, ∼5–6L, and ∼13–17L, respectively. The gas-sensing attributes of 2H-WSe2 nanosheets are investigated thoroughly. Room temperature (RT) experiments show that these devices are specifically tailored for NO2 detection. 2L WSe2 nanosheets deliver the best rapid response compared to ∼5–6L or ∼13–17L. The response of 2L WSe2 at RT is 250, 328, and 361% to 2, 4, and 6 ppm NO2, respectively. The sensor showed nearly the same response toward low NO2 concentration even after 9 months of testing, confirming its remarkable long-term stability. A selectivity study, performed at three working temperatures (RT, 100, and 150 °C), shows high selectivity at 150 and 100 °C. Full selectivity toward NO2 at RT confirms that 2H-WSe2 nanosheet-based sensors are ideal candidates for NO2 gas detection.
Highlights
Fossil fuel combustion and automotive emissions always result in highly toxic emissions
The results indicate that the pristine material synthesized according to our previous synthetic protocol is a phase pure material with a hexagonal crystal system of space group P63/mmc and space group no. 194
The liquid-phase exfoliated (LPE) of 2H-WSe2 nanosheets from the WSe2 bulk, allows the smooth homogeneous dispersion of the material in a suitable solvent, which was relatively stable till 60 days
Summary
Fossil fuel combustion and automotive emissions always result in highly toxic emissions. The WSe2/carbon composite architecture has excellent performance as a new and efficient anode material in SIB owing to its multilayer structure and large interlayer spacing that helps facilitate and further increase the intercalation of sodium ions.[32,33] WSe2 has shown its capability as a suitable candidate for solar water splitting Hybrid structure such as carbon nanotube/WSe2 exhibits superior performance in photodegradation of the organic dye methyl orange.[34,35] Highperformance flexible solar cells are widely investigated using multiple layers of WSe2 due to which high-power conversion efficiency is achieved.[36] Among all the widely researched TMDCs, 2H-WSe2 is a commonly known semiconductor which shows its ability toward detecting toxic gases such as NO2.27 Previous reports by several groups demonstrate a p-type field-effect transistor based on mechanically exfoliated 2H-WSe2 monolayers for NO2 detection where palladium (Pd) was used as the source and drain electrodes to lower the contact resistance for hole injection.[24] Upon exposure to 0.05% of NO2, the source−drain current increased 5 orders of magnitude due to the decrease of the Schottky barrier and the increase of p-doping.[24].
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