摘要
为提高TiO2的光吸收和光催化能力,采用原位水热还原法将Au沉积到有序多孔TiO2上,制备了有序大孔-介孔Au-TiO2复合材料。材料的光催化活性以在紫外光和可见光辐射下降解罗丹明B来评价。漫反射吸收光谱显示Au-TiO2复合材料在400-800nm有较强的吸收。在紫外光和可见光辐射下,Au-TiO2复合材料的光催化活性优于TiO2。在紫外光下Au-TiO2-1.9是最高效的催化剂,3h内罗丹明B的降解率达84%,其表观速率常数K是TiO2的2.8倍。这主要是因为沉积Au纳米粒子能有效促进电荷的分离,提高光催化效率,但过量的Au成为表面电子-空穴复合的中心,反而降低其光催化能力。在紫外光下,罗丹明B的降解反应属于准一级动力学反应,光生空穴是主要的活性物质。阻抗测试显示Au-TiO2的圆弧半径小于TiO2,表明电荷传递效率提高,有利于光生电子-空穴对的分离和光催化性能的提高。
Aimed at enhancing photocatalysis through intensifying light harvesting,a new photocatalyst was fabricated by infiltrating Au nanoparticles into hierarchical macro-mesoporous TiO2 via in situ hydrothermal reduction. The photocatalytic activity were evaluated by the decomposition of Rhodamine B under UV and visible light radiation. The absorption spectra of Au-TiO2 composites extended into the visible region of 400-800nm. Au-TiO2 were found to exhibit remarkably higher photocatalytic activities than pure TiO2 under both UV and visible light radiation. Au-TiO2-1.9 was proved to be the most efficient photocatalyst whose apparent rate constant was 1.8 fold larger than that of TiO2 under UV irradiation. The increased photoactivity can be mainly attributed to Au nanoparticles which can suppress charge recombination efficiently. In contrast,excess Au acts as electron-hole recombination centres and reduces the photocatalytic degradation ratio. The dye degradation followed pseudo-first-order kinetics and photogenerated holes were the main active species under UV irradiation. As smaller arc radius of Au-TiO2 implied a higher efficiency of charge transfer,the dramatically enhanced separation efficiency of photogenerated electron-hole pairs and higher photocatalytic activities in Au-TiO2 can be determined.
出处
《化工新型材料》
CAS
CSCD
北大核心
2015年第3期136-139,共4页
New Chemical Materials
基金
国家杰出青年科学基金(21125628)
国家自然科学基金青年科学基金(21006008
21206014)
