【作者】 靳尉仁；

【导师】 潘海波；

【作者基本信息】 福州大学 ， 物理化学， 2004， 硕士

【摘要】 TiO2是一种宽禁带（3.2eV）半导体，只能吸收利用太阳光中的紫外线部分，太阳能利用率低；另一方面，光生电子－空穴对易复合，量子效率较低。提高TiO2吸收光谱范围和光催化量子效率成为半导体光催化技研究的中心问题。本文选择了具有高稳定性和高催化性能的酞菁配合物（MPc，M=Fe,Mn）作为敏化剂，尝试把MPc在可见光区的强吸收性及催化特性与TiO2光催化特性集为一体，应用溶胶－凝胶方法制备出高催化活性和宽响应范围的新型光催化剂。1、制备了具有高催化活性的复合光催化剂。MPc与TiO2之间形成较强的相互作用，可以促进光生电子的转移，降低光生载流子的复合几率，进而提高光催化活性。同时，MPc在可见光区具有较强的吸收光子的能力，可以拓展光催化剂的光谱响应范围。在无外加氧化剂，FePc/ TiO2在紫外光照射下，在10min内可将1×10－5mol/L的罗丹明B降解至无色，降解率达99％；FeClPc/TiO2在太阳光下60min可将同浓度罗丹明B降解至无色；150min将甲基橙（3×10－5mol/L）降解至无色；12h使对氯苯胺溶液的COD值从500 mg/L降到400 mg/L。2、研究了复合光催化剂制备过程的影响因素。MPc的含量较少时敏化效果不明显，含量过多时又可能成为复合中心，并阻碍TiO2吸收光子；对FePc和FeClPc的最佳含量是1：400，MnPc则是1:1200。煅烧温度较低不利用MPc与TiO2形成强相互作用，达不到敏化的效果；温度过高则会使FePc分解，使光催化活性降低，250℃为最佳的煅烧温度。溶胶－凝胶过程中，pH值控制钛酸丁酯的水解和团聚，但不同pH值对光催化活性影响不大。超临界干燥技术是一种无氧过程，可避免MPc在合成过程中发生分解。FeClPc稳定性较强，在合成过程中不易被分解，因此FeClPc/TiO2光催化剂在可见光区具有较强的吸收光子能力和光催化活性。3、提出了复合光催化剂在紫外光和可见光区域两种不同的反应机理。在紫外光区是TiO2吸收光子然后激发电子到导带上；在可见光区是MPc吸收光子被激发，然后发生电子转移反应，二者的反应机理不一样，造成MPc/TiO2复合光催化剂在紫外光区和可见光区域的活性顺序不同。更多还原

【Abstract】 TiO2 is a kind of semiconductor with wide band gap, it can only absorb the ultraviolet ray of sunlight, the harvest of solar light is low. Another disadvantage of photocatalytic systems upon band gap excitation of the semiconductors is the high degree of recombination between the photogenerated charge carriers. As a result of this recombination the photocatalyst efficient is decreased as well as the quantum yield. To improve the quantum yield and broaden the absorbing spectrum range becomes a very important problem in the research field of photocatalysis.We chose MPc (M=Fe,Mn) as sensitizied materials, which have high stability and catalytic activity. With taking the advantage of the excellent property of both MPc and TiO2, a novel photocatalyst with high photo-quantum yield and responsibility at widened spectrum range was prepared by sol-gel process 1、MPc/TiO2 hybrid photocatalysts with higher catalytic activity were prepared by sol-gel method. A strong action could be formed between MPc and TiO2, thus the transfer of photo-excited electron can be accelerated, and the recombination of photo-induced carriers can be reduced. The photocatalytic activity of these hybrid photocatalysts is greatly improved also. At the same time, the sunlight can be absorbed and excited by MPc, thus it broadens the absorbing spectrum range.Without oxidant introdued to the reaction system, the RhB at the concentration of 1×10－5mol/L by FePc/TiO2 was degradated completely within 10 minutes under ultraviolet ray. The degradation efficient is reach to 99%. While the RhB at same concentration within 60 minutes and the methyl orange (3×10－5 mol/L) within 150 minutes were degraded all by FeClPc/TiO2 under sunlight. The chemical oxygen demand of p－chloroaniline was droped from 500 mg/L to 400mg/L by FeClPc/TiO2 in 12 hours under sunlight.2、The factors for the catalytic activity of MPc/TiO2 hybrid photocatalysts during the preparation were studied. If the content of MPc is too low, the sensitized effect is not obvious, but that of MPc is too high, MPc will become the recombined sites of photogenerated <WP=5>carriers again and absorbing ligh are prevented at the surface of TiO2. The optimal contents for the sensitized MPc are different from MPcs. For FeClPc and FePc, the optimal mol ratio of MPc to TiO2 is 1:400, for MnPc, it is 1:1200. Low calcinations temperature is not advantageous to form strong interaction between MPcs and TiO2, and if the temperature is too high, MPcs is discomposed partially due to MPc oxidated by oxygen. The calcinations temperature at 250℃ is the optimal temperature. The pH could effect the hydrolysis of Ti(C4H9O)4 during the sol-gel process and the growth of particles, but the influence on the activity of catalysts is not obvious.Supercritical fluid drying technology is a process without oxygen, so it can prevent MPc from decomposing or oxidizing at the process.FeClPc is stable and not be decomposed during the preparation process, so FeClPc/TiO2 hybrid photocatalyst has a strong light absorption and high activity in visible light region. 3、Different photocatalytic mechanisms of MPc/TiO2 hybrid photocatalysts under untraviolet ray and visible light are suggested. The photoexcitation with ultraviolet ray yields the electron-hole pair by TiO2. It is MPc at the initial excitation under visible light, so more MPc is in favor of absorbing sunlight. The activity sequence of MPc/TiO2 hybrid photocatalyst under ultraviolet ray varies from that under visible light.更多还原