权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Clarification of Mechanisms for Surface Photoreactions and Improvement of Photocatalytic Activity for Visible-light Responsive Metal Oxides

阐明表面光反应机理并提高可见光响应金属氧化物的光催化活性

基本信息

批准号：
16350114
负责人：
NAKATO Yoshihiro
金额：
$ 10.3万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

With an aim to improve the activity of TiO_2 and related metal-oxide photocatalysts for solar water splitting and photodecomposition of harmful organic compounds, we have studied molecular mechanisms of surface photoreactions on TiuO_2 (rutile) and explored new active visible-light responsive metal-oxide photocatalysts. At first, we have succeeded in preparing atomically flat and stable n-TiO_2 (rutile) (110) and (100) surfaces by a novel method of HF-etching and annealing at 550℃. This success has for the first time enabled us to reveal interesting crystal-face dependences of important properties of TiO_2 (rutile), such as the flat-band potential (U_<fb>), the hole reactivity, and the photoluminescense (PL) spectrum which arises from a precursor (called surface-trapped hole, s.t.h.) of photooxidation reaction of water on TiO_2. In addition, we have clarified that the occurrence of the photooxidation reaction of water on the atomically flat TiO_2 (110) and (100) surfaces has led to their roughening on an atomic scale together with weakening of the PL intensity. These results have been explained well by our recently proposed mechanism that the photooxidation reaction of water on TiO_2 is initiated by a nucleophilic attack of water (Lewis base) to the surface-trapped hole (s.t.h.) (Lewis acid), giving strong support to the mechanism. In order to investigate further the validity of the mechanism, we have also studied the mechanism for the water photooxidation reaction on nitrogen-containing metal oxides, such as N-doped TiO_2 and TaON, and found that the reaction proceeds by the same mechanism as on TiO_2 as well. Furthermore, we have explored new visible-light responsive metal-oxide photocatalysts and found that mixed metal oxides such as BiCu_2VO_6 and BiZn_2VO_6 show higher activity that BiVO_4 that is known as one of the most active visible-light driven photocatalysts.

为了提高TiO_2及相关金属氧化物光催化剂在太阳能水分解和光分解有害有机化合物中的活性，我们研究了TiuO_2（金红石）表面光反应的分子机理，探索了新型的可见光活性金属氧化物光催化剂。首先，我们成功地用一种新颖的方法在550℃的高频蚀刻和退火下制备了原子平坦的n-TiO_2（金红石）（110）和（100）表面。这一成功使我们第一次揭示了TiO_2（金红石）重要性质的有趣的晶面依赖性，如平带电位（U_<fb>），空穴反应性，以及由水在TiO_2上光氧化反应的前驱体（称为表面捕获空穴，s.t.h）产生的光致发光（PL）光谱。此外，我们还澄清了水在原子平面TiO_2（110）和（100）表面上发生的光氧化反应导致了它们在原子尺度上的粗化和PL强度的减弱。我们最近提出的机理很好地解释了这些结果，即水在TiO_2上的光氧化反应是由水（Lewis碱）对表面捕获孔（s.t.h）的亲核攻击引起的。（路易斯酸），为该机理提供了强有力的支持。为了进一步研究该机理的有效性，我们还研究了含氮金属氧化物（如n掺杂TiO_2和TaON）上的水光氧化反应机理，发现该反应与TiO_2上的反应机理相同。此外，我们还探索了新的可见光响应型金属氧化物光催化剂，发现BiCu_2VO_6和BiZn_2VO_6的混合金属氧化物比BiVO_4表现出更高的活性，BiVO_4被认为是最活跃的可见光驱动光催化剂之一。