RGO-Modified Semiconductor Heterojunction Interface Regulation Improves Detection Of Nitrogenous Harmful Gases

Gas sensing technology plays a vital role in environmental detection,chemical process control,agricultural and medical applications,especially for some industries,detecting nitrogenous harmful gases such as nitrogen dioxide(NO2)and triethylamine(TEA)etc.is very important.The raw materials of semiconductor sensors have a series of characteristics such as easy availability,simple manufacturing process and low cost,and are widely used to detect various toxic and harmful gases.However,the need to work at higher ambient temperatures and poor selectivity greatly limits the wide application of this material in the field of gas sensors.Two-dimensional graphene is considered to be a promising gas-sensitive material because of its large specific surface area,good electrical conductivity and mechanical properties.In recent years,researchers have tried to compound metal oxide semiconductors(MOS)with graphene or graphene derivatives to improve the gas-sensing performance of MOS.The purpose of this paper is to explore the p-n heterojunction formed by combining NiO,WO3 with other semiconductor materials such as BiV04,and then use reduced graphene oxide(rGO)to modify and adjust the heterojunction interface to synthesize semiconductor metal oxide composite with high gas sensitivity under low temperature.The new ternary heterojunction gas-sensitive material synthesized in this experiment has not been reported so far in the field of sensors.The main research contents are as follows:1.In order to improve the gas-sensing performance of p-type semiconductor NiO,the compounding of semiconductor heterojunction with rGO is considered to be an effective improvement method.In this paper,graphene oxide(GO)was synthesized by the two-step oxidation and improved Hummers method,and 3.7 wt%rG0-NiO-BiV04 nanocomposite was successfully synthesized by simple hydrothermal and metal organic decomposition methods.The gas-sensitivity test results show that the ternary material exhibits rapid response to 2 ppm NO2 at a low temperature of 60?,and the response values are 4 times and 8 times that of rGO-NiO and pure NiO,respectively.The gas-sensitive response of the material to a variety of reducing gases such as formaldehyde,toluene,etc.was explored and found to have the highest response to NO2.The improvement of gas sensing performance is attributed to the rapid transfer of electrons at the heterojunction interface and the increase in surface area and defect concentration after loading rGO.This work has a reference value for improving the gas-sensing performance of p-type semiconductors.2.In order to improve the gas sensitivity of WO3 to triethylamine(TEA),WO3-NiO-rGO nanocomposite was successfully synthesized by hydrothermal and thermal reduction methods.The response of the optimum component is 4 times that of pure WO3,the response time to 7.5 ppm TEA is extremely short,only 16 s,and the response limit concentration is only 0.561 ppm.The mechanism of gas sensitivity enhancement was discussed in detail.Due to the formation of heterojunction and the introduction of rGO,the former lowered the barrier to facilitate carrier transport,and the latter increased the specific surface area and accelerated the electron migration rate.This research is expected to be widely used in the development of rGO-MOS and heterojunction gas sensors.