The Preparation Of MPc/SnO₂ And The Properties On Its Liquid-solid, Gas-solid Interface

Through summarizing the related references, reviewing the structure, physical and chemical properties, researching development of phthalocyanine compound and SnO₂, we established this study on the preparation of cobalt phthalocyanine-SnO₂ (CoPc/SnO₂), nickel phthalocyanine-SnO₂ (NiPc/SnO₂), copper phthalocyanine-SnO₂ (CuPc/SnO₂) and zinc phthalocyanine-SnO₂ (ZnPc/SnO₂) composites with different mole proportion of metallophthalocyanine (MPc) and SnO₂. We researched photo catalytic activity under visible light and gas-sensitivity to trimethylamine (TMA) gas of these MPc/SnO₂ composites. It is important to inspect the environment by their TMA gas-sensitivity and is availability to exploit more solar energy by their photosensitivity under visible light. This study is made up of the following three parts:1. Synthesis of MPc/SnO₂ composites. Metallophthalocyanines including CoPc, NiPc, CuPc and ZnPc were produced by phthalic anhydride in solid state or in an inert high-boiling solvent. The MPcs' yields in an high-boiling solvent were 29.4%, 30.0%, 28.0%, 29.1%, and in solid state were 58.5%, 62.5%, 52.3%, 36.4%. The reactions in solid state had higher yields and less pollution, so MPcs produced in solid state were used to prepared MPc/SnO₂ composites in which the mole ratio of MPcs to SnO₂were 1:200, 1:100, 1:75 and 1:50. Some characteristic absorption peak of MPc and SnO₂ shifted red in IR spectra of MPc/SnO₂ composites, and the vibration absorption peak of M-O were appeared in its IR spectra. It illustrated that there was effective complex between MPc and SnO₂ by partial chemical bonding. The XRD results of MPc/SnO₂ composite showed that the average grain diameters of MPc/SnO₂ composites were smaller than SnO₂ that was not compounded with MPc. MPc/SnO₂ composites in water solution were with negative charges, the isoelectric points were between pH 2.13 and pH 3.10.2. Study on MPc/SnO₂ composites' photosensitivity under visible light. The photo catalytic activity of MPc/SnO₂ composites was investigated by using the photo catalytic degradation of 10^-5 mol/L Rhodamine B (RB) as a model reaction in room temperature and under visible light with its light intensity was about 3000 Lux. Compared to SnO₂, MPc/SnO₂ composites' photo catalytic degradation ratio to RB increased from 19.8% to 42.3%, 64.3%, 21.2%, 23.1% by compounded different MPcs with SnO₂ The photo catalytic degradation ratio of TiO₂ to RB under the same conditions was 31.2% and MPc/SnO₂ composites prepared by immersion method was less than 20%. CoPc/SnO₂ and NiPc/SnO₂ composites had the best photo catalytic activity in these MPc/SnO₂ composites. The photo catalytic degradation ratio of 1:200, 1:100 CoPc/SnO₂ composites were 40.7%, 42.3% and 1:100, 1:75, 1:200 NiPc/SnO₂ composites were 34.9%, 39.5%, 64.3%. They had better photo catalytic activity than TiO₂ under room temperature and visible light about 3000 Lux.3. Research on MPc/SnO₂ composites' gas-sensitivity to TMA gas. The conductivity ion chromatography method was used to determine trimethylamine in air which was absorbed by sulfuric acid solution with pH=1. The concentration of trimethylamine was linear with peak area in rang of 3.9mg/L～97.0mg/L.The recoveries were 98.02%～103.57% and the relative standard deviation was 98.02%～103.57%. The results indicated that the method had high sensitivity and was very useful to determine the trimethylamine in gas phase. We determined the concentration of the TMA gas used in the experiment was 0.88 mg/ml by the conductivity ion chromatography method. 1:200, 1:100, 1:75 MPc/SnO₂ composites were rubbed and spread on the surfaces of the electrodes. Then through the processes of activation and aging, the lateral-heating sense organs were made. These sense organs were put in the gas sensitive testing system to test separately their resistances in the air (Ra), and in the atmosphere of TMA gas (Rg), and then we got the sensitivities S. Compared to SnO₂, the highest of MPc/SnO₂ composites with different MPcs were increased from 4.4 to 11.4, 10.2, 6.0, 9.4. CoPc/SnO₂ and NiPc/SnO₂ composites had the best gas-sensitivity in these MPc/SnO₂ composites.In this paper, NiPc/SnO₂ composite's excellent photo catalytic activity under visible light, the conductivity ion chromatography method used to determine trimethylamine in air and the lateral-heating sense organs made by MPc/SnO₂ composites to test TMA concentration were scarce. All of these will develop the application of MPcs and SnO₂ and will be more and more significance. The research of MPc/SnO₂ composites on photosensitivity will be used in solar cells and their gas-sensitivity will be used in gas sensors.