【作者】 王梅；

【导师】 黄伟新；

【作者基本信息】 中国科学技术大学 ， 物理化学， 2019， 硕士

【摘要】 Ti02基催化剂广泛用于光催化分解水制氢反应和丙烯环氧化反应。本论文制备并研究了TiO2基催化剂在光催化分解水制氢反应和丙烯环氧化反应的催化性能,取得的主要结果如下:1.以H2PtCl6水溶液为前驱体,用光沉积的方法在Cu2O-TiO2复合材料表面负载Pt,发现在光沉积Pt的过程中,氧化物的等电点起着关键的作用。在光沉积条件下,Pt金属颗粒易于沉积在TiO2载体上;在Cu2O-TiO2复合载体上,Cu2O表面带正电荷并富含光激发的空穴,而TiO2表面带负电并富含光激发的电子,Pt的前驱体PtCl62-阴离子优先吸附在Cu2O-TiO2复合材料的带正电的Cu2O表面上,最终形成Pt氧化物颗粒,而少量吸附在TiO2表面上的Pt前驱体最终形成Pt金属颗粒。Cu2O-TiO2复合材料中Pt氧化物的比例随Cu2O量的增加而增加,导致Pt/Cu2O-TiO2复合光催化剂在光催化水还原反应中的活性降低。这些结果加深了对氧化物复合材料表面光沉积过程的理解。2.以HF(aq)作为封端剂,通过调节水热方法的水热温度以及加入的HF(aq)的量,制备出具有不同厚度和{001}晶面比例的TiO2纳米片。加入同样量HF(aq)制备的TiO2纳米片{001}晶面所占比例越大,光解水产氢活性越高;同一水热温度制备的TiO2纳米片尺寸越小,光解水产氢活性更高。3.以上述TiO2纳米片为载体,用氨水作为沉淀剂,用沉淀沉积方法制备的1%-Au/TiO2{001}催化剂在丙烯环氧化反应中,具有更高{001}晶面比例的1%-Au/TiO2(001}催化剂表现出更高的环氧丙烷产率,表明{001}晶面有利于丙烯环氧化反应。更多还原

【Abstract】 TiO2-based catalysts are widely used in photocatalytic water reduction reaction and propylene epoxidation reaction.In this thesis,several TiO2-based materials were prepared and studied as catalysts for photocatalytic water reduction reaction and propylene epoxidation reaction.The main results are as follows:1.Pt/Cu2O-TiO2 catalysts were prepared by photodeposition of Pt on Cu2O-TiO2 composite surfaces employing H2PtCl6 aqueous solution as the precursor,in which a key role of isoelectric point of oxide surfaces on the Pt photodeposition process was revealed.Under the photodeposition conditions,Pt metal particles are facilely photodeposited on TiO2 support;on Cu2O-TiO2 composite supports,the Cu2O surface is positively charged and enriched with photo-excited holes while the TiO2 surface is negatively charged and enriched with photo-excited electrons.This leads to the preferential adsorption of PtCl62-anion precursor on the Cu2O surface of Cu2O-TiO2 composite and the dominant formation of Pt oxide particles on Cu2O surface but few Pt metal particles on TiO2 surface.Consequently,the activity of resulting Pt/Cu2O-TiO2 composite photocatalysts in photocatalytic water reduction decreases as the Cu2O content increases.These results deepen the understanding of photodeposition processes on oxide composite surfaces.2.Anatase TiO2 nanosheets with different ratios of{001} facets were prepared via adjusting the hydrothermal temperature and the amount of HF(aq)capping agent during the hydrothermal method,and used as photocatalysts for photocatalytic water reduction.The catalyst with a larger proportion of{001} facets is more active among TiO2 nanosheets prepared using the same amount of HF(aq)capping agent,while the one with a smaller size is more active among TiO2 nanosheets prepared at the same hydrothermal temperature.3.1%-Au/TiO2 {001} catalysts were prepared by precipitation deposition method with ammonia as a precipitant using anatase TiO2 nanosheets with different ratios of{001} facets as supports and used as catalysts for propylene epoxidation.The catalyst with a higher ratio of {001} facets shows a larger propene oxide yield,indicating that the anatase TiO2 {001} facets in Au/TiO2 catalysts benefit the propylene epoxidation reaction.更多还原