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.

为了改善TIO_2和相关金属氧化物光催化剂的活性，用于太阳能水分分裂和有害有机化合物的光电分解，我们具有TIUOO_2（lutile）表面光电反应的Studiod分子机制（lutile）（lutile）（lutile）（lutile），并探索了新的活跃的可见响应性金属氧化金属 - 氧化物光电剂。最初，我们通过一种新型的HF蚀刻和退火方法在550℃中成功准备了原子平坦和稳定的N-TIO_2（金红石）（110）和（100）表面。这一成功首次使我们能够揭示Tio_2（lutile）重要特性的有趣的晶体面依赖性，例如平移电位（U_ <fb>），孔反应性和光效率（PL）光谱，这些光谱（PL）光谱是由PROCSOR（称为表面跟踪的孔，S.T.T.H.）引起的。此外，我们已经阐明了水在原子扁平的TIO_2（110）和（100）表面上的光氧化反应的发生导致它们在原子尺度上进行粗糙，同时PL强度的弱化。我们最近提出的机制很好地解释了这些结果，即水对TIO_2的光氧化反应是由水（Lewis碱基）对表面陷阱孔（S.T.H.）（Lewis Acid）（Lewis Acid）（Lewis base）（Lewis Acid）引发的，从而对该机理产生了强有力的支持。为了进一步研究该机制的有效性，我们还研究了含氮金属氧化物（例如N掺杂TIO_2和TAON）上水光氧化反应的机制，并发现该反应也与TiO_2相同的机制进行。此外，我们已经探索了新的可见光响应金属氧化物光催化剂，发现混合金属氧化物（例如BICU_2VO_6和BIZN_2VO_6）显示出较高的活性，即BIVO_4，该活性被称为最活跃的可见光 - light-Light-Light-Light-Light驱动式光催化剂之一。