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Advanced functional materials: highly selective NO2 room temperature gas sensor based on MoS2 van der Waals p-n junction

wallpapers News 2020-10-12

environmental pollution problems such as automobile exhaust haze acid rain seriously damage people's health. With the continuous enhancement of people's awareness of environmental protection high sensitive detection technology is urgently needed to detect toxic harmful gases in time. Traditional metal oxide semiconductor (MOS) gas sensors have the disadvantages of poor selectivity high working temperature (usually 200 ~ 400 ℃) high power consumption high temperature conditions can easily shorten the service life of the sensor. Although some room temperature MOS gas sensors have been reported in the past low sensitivity slow response recovery rate incomplete recovery are still challenges for room temperature sensors. In recent years van der Waals heterostructures based on two-dimensional materials have shown great potential in photoelectric detection gas detection. The unique physical chemical properties of two-dimensional materials make it possible to develop ultra-high sensitivity low power consumption room temperature gas sensors. Among them MoS2 has become a hot research object of room temperature gas sensor due to its relatively simple preparation method adjustable electrical performance good chemical stability which is used to detect NO2 NH3 triethylamine other toxic harmful gases. Although these sensors show high detection sensitivity low detection limit their disadvantages such as poor selectivity poor stability slow recovery need to be further solved.

recently the team of Zhang Jun from school of physical sciences of Qingdao University Professor Nicola pinna from Humboldt University of Germany jointly prepared n-type MoS2 p-type MoS2 by traditional chemical vapor deposition (CVD) soft chemistry respectively constructed MoS2 van der Waals p-n junction by wet transfer method. The gas detection properties of n-type p-type MoS2 MoS2 p-n junction were systematically studied. The results show that n-type MoS2 has the highest sensitivity to triethylamine the detection limit is 0.1 ppm P-type MoS2 has fast response to NO2 but the two kinds of gas sensors show cross response to other gases have the disadvantages of slow recovery incomplete recovery; while p-n junction gas sensors based on n-type MoS2 p-type MoS2 show excellent selectivity to NO2 their response is (20 Compared with the single p-type MoS2 sensor the detection limit of MoS2 sensor is as low as 8 ppb more importantly the sensor can achieve rapid complete recovery within 30 s under the assistance of UV light. The excellent detection performance is mainly due to the unique photoelectric properties of p-n junction the effective control of gas adsorption on the interface barrier height. This study provides an example for the construction of two-dimensional van der Waals homojunction the application of high sensitivity high selectivity room temperature gas sensor.

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