Synthesis And Optical Sensing Properties Of Composite Materials Based On Inorganic Nanosheets

Among the numerous nano-inorganic solids,two-dimensional inorganic nanosheets have attracted widespread attention due to their unique advantages such as large surface area,numerous active sites,and good biocompatibility.Montmorillonite(MMT)and layered double metal hydroxide(LDH)are common two-dimensional inorganic layered materials,which can be easily stripped into nanosheets by simple methods.The nanosheets can provide a stable environment for the light-emitting molecules,the molecules are uniformly loaded,so the aggregation and quenching of the light-emitting molecules are avoided,and the optical performance of the light-emitting molecules can be improved when nanosheets and organic light-emitting molecules are combined,thereby excellent optical properties of composite materials can be obtained,and applied to optical sensing.In this thesis,two composite materials were prepared based on the larger specific surface area and good stability of MMT and LDH nanosheets.The main research contents are as follows:1.The organic light-emitting molecule 1,2,4-triaminoaniline dihydrochloride(C6H11Cl2N3)was compounded with MMT nanosheets,and carbon dots(CDs)complex(MMT-CDs)were obtained through high temperature hydrothermal.The morphology,structure and optical properties of MMT-CDs were studied.The large specific surface area,high optical and chemical stability of MMT nanosheets made MMT-CDs show more excellent fluorescence optical properties than the high-temperature hydrothermal products of the luminescent molecules themselves.In terms of pH fluorescence response,it also appeared a wider linear range and high sensitivity,therefore,MMT-CDs have great potential in the direction of optical pH sensing.2.The organic light-emitting molecule 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt(HPTS),LDH nanosheets,and polyvinyl alcohol(PVA)were compounded,and HPTS-LDH-PVA film was prepared by solvent evaporation method.The morphology,structure and fluorescence properties of the HPTS-LDH-PVA film were studied.LDH nanosheets have good hydrophilicity and can uniformly disperse HPTS;PVA has excellent film-forming properties,giving the film a uniform,smooth and continuous structure and morphology.Compared with HPTS solution,it has better fluorescence performance and pH sensing performance.In addition,the film was used to detect low-concentration ammonia water,achieving high-sensitivity monitoring with a detection limit of 0.31 ppm.