The Preparation And Sensitive Properties Of Nano Materials For Rapid Detection Of VOCs Based On Cataluminescence

Volatile organic matter(VOCs)is an important precursor to forming secondary pollutants such as fine particulate matter(PM2.5)and ozone(O₃),thus causing atmospheric environmental problems such as haze and photochemical smog.At present,the common detection techniques of VOCs include spectrophotometry,gas chromatography,high performance liquid chromatography,mass spectrometry,gas chromatograph-mass spectrometer and so on.However,most of these methods have the disadvantages of large volume,high price,cumbersome and time-consuming in the process of detection process.Hence,the development of new methods and techniques for rapid detection of VOCs has become a current research hotspot.Cataluminescence technology has been widely used in environmental monitoring,drug analysis,food analysis and immunoassay because of its high sensitivity,small background interference,low detection limit and fast detection speed..In addition,the development of nanotechnology provides a new opportunity for cataluminescence.Nanomaterials have the characteristics of large specific surface area,high surface reaction activity,strong adsorption ability and high catalytic efficiency,which is of great significance to further broaden the application of cataluminescence methods in environmental monitoring and other fields.In this paper,a variety of nanomaterials were prepared and used in the detection of many VOCs.The results show that the prepared nano-materials can produce cataluminescence signal with alcohols,toluene,ether,trichloroethylene and other VOCs,Therefore,cataluminescence gas sensors of four VOCs were designed using these nano-sensitive materials,and their sensitive characteristics and mechanism were systematically studied.A brief description of the research is given below:1.The flower-like Na₂Mg(CO₃)₂nanomaterials were prepared by hydrothermal method and used for multidimensional signal detection of methanol,ethanol,n-propanol and n-butanol by single-sensitive material cataluminescence method.X-ray diffraction(XRD),scanning electron microscope(SEM)and energy dispersive spectrometer(EDS)were used to preliminarily characterize the crystal structure,morphology and composition of nano-Na₂Mg(CO₃)₂.The results of cataluminescence show that the response signals of the four alcohols are relatively stable.The materials have the characteristics of fast response speed and short recovery time to the four alcohols,and the response time is between 1 and 2 s.The response signal intensity for each alcohol varies with the same concentration of the four alcohols,and the average one-time response recovery period for the four alcohols is also different.According to the results of selective study,the material has only a weak response signal to formaldehyde except for four alcohols.On this basis,the four alcohols can be effectively identified from response recovery period,signal strength and multidimensional signals of a single sensor.2.Two-dimensional nanocomposite Pt/Ti₃C₂T_x-CNT was prepared,and used for the rapid detection of toluene at low temperature.It was characterized by transmission electron microscopy(TEM),XRD,Mapping,and SEM,and the results show that the material is a tubular structure connected by nodes,and Pt is uniformly attached to the surface.The results of cataluminescence experiments show that Pt/Ti₃C₂T_x-CNT exhibits the best catalytic performance for toluene,and the response signals are relatively stable.Under the best reaction conditions,the linear concentration range is between 2.5?87 ppm,the correlation coefficient R equal to0.9904,and the detection limit is about 2 ppm.The sensor has the advantage of fast response,the response time is about 1 s.Cataluminescence is used to detect toluene at about 150?,which is significantly lower than the results reported in the literature on cataluminescence detection of toluene.3.The luminescent composite material GO/Mo₂Ti C₂T_xwas prepared and used for the detection of ether by the cataluminescence method.It was characterized by TEM,XRD,Mapping,and SEM.The characterization results show that the material has a fish-scale structure and is evenly distributed.Cataluminescence experiment results show that the sensor's response signal to ether is relatively stable,the signal intensity of four repeated experiments is almost unchanged.The response speed of the sensor is fast,and the response time is about 2 s.At the same time,the detection limit is low to 0.64 ppm.Within the concentration range of 9.5?950 mg/L,the intensity of cataluminescence signal shows a good linear relationship with the concentration of ether(R=0.9952)..In addition,repeated tests of 10 common volatile organic compounds show no reaction except acetone,but the interference degree of acetone is less than 1%,indicating that it has good selectivity.4.The nanocomposite PEG200/ZnO was prepared by hydrothermal method,and the cataluminescence behavior of trichloroethylene on its surface was studied.Fourier Infrared Spectroscopy(FT-IR),SEM and EDS were used to characterize nano-PEG200/ZnO.The results show that PEG200 does not change the morphology of nano-ZnO,but combines with nano-ZnO in the form of a binder to form a package,and the surface is loose and flocculent.This structure can increase the residence time of gas on the surface.The results of cataluminescence experiments show that the response signal of nano-ZnO doped with PEG200 is more stable than that of undoped,and the reaction time and recovery time are significantly shortened.The·OH free radicals provided by the PEG200 for the cataluminescence reaction can effectively promote the occurrence of the cataluminescence reaction and reduce the activation energy required for the reaction,thus reducing the temperature required for the experiment.According to the experimental results at different temperature and flow rate,the optimum reaction temperature and air flow rate are120 ^oC,180 m L/min,and there is a good linear relationship between the relative cataluminescence intensity and the concentration of the detected substance(y=28.588 x-285.56,R=0.9593).