Study On Preparation And Gas Sensing Performance Of Zinc Phthalocyanine Film And Its Composite Film With Metal Oxide(TiO₂,NiO) Based Optical Waveguide Component

Phthalocyanine complexes are a class of compounds with macrocyclic conjugated structures.Because of their high sensitivity and selectivity to specific gases at room temperature,they are a versatile and widely studied organic gas-sensitive material in recent years.TiO₂and NiO are important components of inorganic functional materials.Because of their excellent chemical and thermal stability,simple preparation,and non-toxicity,they are widely used in many fields.In this paper,the sol-gel method was used to prepare TiO₂and NiO sol,and the sensitive elements were prepared with zinc phthalocyanine(Zn Pc),Zn Pc-TiO₂,NiO sol-Zn Pc as the sensitive materials,respectively,and their gas-sensitive properties were studied.This paper is composed of 5 parts.The introduction part mainly introduces air pollution and types of pollutants,and focuses on the hydrogen sulfide(H₂S)gas in air pollutants,hazards and detection methods;outlines the definition,composition and classification of sensors;the definition,characteristic parameters and classification of gas sensors are introduced;the structure,principle and application of optical waveguide sensors are outlined;the types and applications of gas-sensitive materials are introduced.In the second chapter,using Zn Pc as sensitive reagent,N,N-dimethylformamide(DMF)as solvent,and polyvinylpyrrolidone(PVP)as film-forming agent,a Zn Pc film/K⁺-exchanged optical waveguide sensitive element was prepared by spin coating method,and its gas-sensitive performance was tested at room temperature.In order to optimize the gas-sensing performance of the sensitive element,the rotating speed of the homogenizer,the mass fraction of the Zn Pc solution and the PVP content were screened.It can be seen from the experimental results that when the rotating speed of the homogenizer is 1600 rpm,the mass fraction of the Zn Pc solution is 0.07%,and the PVP content is 1%,the sensitive element has a good selective response to H₂S gas,and response time is 6 s toward 10^-3V/V₀H₂S gas.The minimum concentration of H₂S gas that the sensitive element can detect is 1×10^-7V/V₀.In addition,the sensitive element showed good stability within one month after preparation.By studying the influence of humidity,it is found that the influence of humidity on sensitive element is very small,and because of the water solubility of H₂S gas,H₂S gas is greatly affected by humidity when the humidity is high.In the third chapter,the TiO₂sol was synthesized by sol-gel method,and its powder was characterized by XRD.First,the TiO₂film/tin-diffused optical waveguide sensor was prepared by dip-coating method,and then the Zn Pc-TiO₂composite film/tin-diffused optical waveguide sensitive element was prepared by spin coating method,and its gas-sensitive performance was tested at room temperature.In order to make the sensitive elements show the best gas-sensing performance,the dip-coating speed,the rotating speed and the mass fraction of Zn Pc solution were screened respectively.It can be seen from the experimental results that when the dip-coating speed is 80mm/min,the rotating speed is 1600 rpm,and the mass fraction of the Zn Pc solution is0.05%,the sensitive element exhibits good gas sensing performance for H₂S,and the response time to 10^-4V/V₀H₂S gas is 6 s.The minimum concentration of H₂S gas that the sensitive element can detect is 1×10^-9V/V₀.In addition,the sensitive element showed good stability within one month after preparation.After examining the influence of humidity on sensitive components,it was found that high humidity has a certain effect on sensitive element.In the fourth chapter,the NiO sol was synthesized by sol-gel method.Next,a certain amount of NiO sol was added with different volumes of Zn Pc solution.After ultrasonic mixing,NiO sol-Zn Pc composite film/K⁺-exchanged optical waveguide sensitive element was prepared by spin-coating method and the gas-sensitive performance was tested at room temperature.The experimental results show that when the volume of Zn Pc solution added to the NiO sol is 2 m L and the rotating speed is 2000 rpm,the sensitive element has a good selective response to H₂S gas and The response time to 10^-3V/V₀H₂S gas is 3 s.The minimum concentration of H₂S gas that the sensitive element can detect is 1×10^-9V/V₀.In addition,the sensitive element showed good stability within one month after preparation.By examining the influence of humidity on sensitive elements,it is found that humidity has little effect on sensitive elements.In the fifth chapter,the gas-sensing mechanism when H₂S gas interacts with the sensitive element is discussed,and the gas-sensing mechanism discussed is verified from the perspective of solution and film.