【作者】 陈姗姗；

【导师】 李怀祥；

【作者基本信息】 山东师范大学 ， 物理化学， 2010， 硕士

【摘要】 近年来,ZnO作为一种用途很广的半导体材料,因其活性高、稳定性好、对人体无毒、成本低且在光催化处理污染水和空气中已广泛应用,而成为最具潜力的光催化剂。然而由于ZnO其固有的缺陷——光生电子-空穴对容易复合,这降低了其光催化活性。因此,要提高ZnO的光催化活性,就应减少光生电子与空穴的复合。将ZnO与其它半导体氧化物复合是提高其光催化活性的途径之一。ZnO和某些半导体材料能级匹配,光生电子和空穴可发生有效的分离,使其复合几率减小,从而提高ZnO的光催化活性。本文主要研究内容如下:（1）以Na₂CO₃和ZnSO₄为原料,采用直接沉淀法制备纯纳米ZnO光催化剂。通过实验确定其具有最佳光催化性能的制备条件:将Na₂CO₃溶液按摩尔比为1.5的比例逐滴加入到ZnSO₄溶液中,在80℃下反应0.5h后,中间产物经无水乙醇洗涤3次后经600℃煅烧1h制得的纳米ZnO具有最佳光催化性能。（2）以Na₂CO₃、ZnSO₄和ZrOCl₂·8H₂O等为原料,采用直接沉淀法经700℃煅烧1h得到的掺锆量为1.0 %（摩尔比）的纳米ZnO复合光催化剂粉体的光催化活性最高。XRD分析说明:随着煅烧温度的升高,纯ZnO和掺锆后的纳米ZnO复合光催化剂晶粒粒径也随之变大,但掺锆可以起到细化晶粒的作用。掺锆以后的纳米ZnO光催化剂的粒径随煅烧温度增长的活化能为16.6kJ/mol,相对于纯纳米ZnO的12.5 kJ/mol有所增大。（3）以Na₂CO₃、ZnSO₄和SnCl₄·5H₂O等为原料,采用直接沉淀法经600℃煅烧1h得到的掺锡量为5.0%（摩尔比）的纳米ZnO复合光催化剂粉体的光催化活性最高。XRD分析表明:随着煅烧温度的升高,纯ZnO和掺锡后的纳米ZnO复合光催化剂晶粒粒径也随之变大,掺锡也可以起到细化晶粒的作用。但与掺锆相比,掺锡细化晶粒粒径的作用更为明显。掺锡以后的纳米ZnO光催化剂的粒径随煅烧温度增长的活化能为6.592kJ/mol,相对于纯ZnO的12.5 kJ/mol减小近一半,这就表明煅烧温度对晶粒粒径大小的影响相对于掺锆而言有所减弱。更多还原

【Abstract】 In recent years, zinc oxide （ZnO） has been a popular photocatalyst for the treatment of organic pollutants in water and air. However, ZnO photocatalysts have an inherent and obvious drawback, that is, the photogenerated charge carriers （hole-electron pairs） can recombine easy. Therefore, improvement of ZnO photocatalytic activity is important to decrease the recombination of photogenerated charge carriers. Coupling ZnO with other semiconductors can provide a beneficial solution in this aspect. The energy gaps of these two semi-conductors are match, which can prevent the recombination of photogenerated charge carriers, and show efficient photoactivity of ZnO. This dissertation consists of following contents:1. The direct precipition method has been used to prepare pure nano-ZnO with Na₂CO₃、ZnSO₄ as raw materials. Determined through experiments with the best photocatalytic activities of the preparation conditions: the Na₂CO₃ solution was added into the ZnSO₄ solution at the ratio of 1.5, at 80℃, reaction for 0.5h, intermediate products were washed three times with ethanol, then calcined at 600℃for 1h. The ZnO nanoparticles showed was produced at this method had the best photocatalytic activity on above mentioned conditions.2. The photocatalysts of Zr-doped ZnO can be synthesized by using the direct-precipition method. Primary optimum content of Zr doping in the samples and calcining temperature for the photocatalytic degradation of methylene blue were 1.0 Zr atom% and 700℃, respectively. X-ray diffraction was used to characterize the grain size of the pure ZnO and Zr-dped ZnO. The size of ZnO nanoparticles increased as calcining temperature. Doping Zr could retard growth of the grain size. Activity energy of the Zr-doped ZnO （1% molar ratio） growth as calcining temperature was 16.6 KJ/mol, bigger than pure ZnO nanoparticles（12.5 KJ/mol）. 3. The photocatalysts of Sn-doped ZnO also can be synthesized by using the direct-precipition method. Primary optimum content of Sn doping in the samples and calcining temperature for the photocatalytic degradation of methylene blue were 5 atom% and 600℃, respectively, which was different from that of Zr-doped ZnO nanoparticles. X-ray diffraction （XRD）, was also used to characterize the grain size of the pure ZnO and Sn-doped ZnO. Size of ZnO particles increased as calcining temperature. Results showed that doping Sn could play a role in reducing the grain size. The activation energy of the 5%Sn-doped ZnO particle size growth with the calcination temperature had been found 6.592 KJ/mol, almost half that of pure ZnO nanoparticles（12.5 KJ/mol）, showing that the effect of calcinations temperature on the grain size was smaller compared to Zr-doping ZnO particles.更多还原